v3 De-couple sysfs memory directories from memory sections

PATCH In review Nathan Fontenot 6 participants 30 messages Jul 20, 2010 – Aug 1, 2010

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Nathan Fontenot

author

2010-07-20 03:46 UTC #0 lore raw

cover v3 De-couple sysfs memory directories from memory sections

This set of patches de-couples the idea that there is a single directory in sysfs for each memory section. The intent of the patches is to reduce the number of sysfs directories created to resolve a boot-time performance issue. On very large systems boot time are getting very long (as seen on powerpc hardware) due to the enormous number of sysfs directories being created. On a system with 1 TB of memory we create ~63,000 directories. For even larger systems boot times are being measured in hours.

This set of patches allows for each directory created in sysfs to cover more than one memory section. The default behavior for sysfs directory creation is the same, in that each directory represents a single memory section. A new file 'end_phys_index' in each directory contains the physical_id of the last memory section covered by the directory so that users can easily determine the memory section range of a directory.

-Nathan Fontenot

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Nathan Fontenot

author

2010-07-20 03:51 UTC #1 lore raw

PATCH 1/8 v3 Move the find_memory_block() routine up

Move the find_me mory_block() routine up to avoid needing a forward declaration in subsequent patches.

Signed-off-by Nathan Fontenot <[email protected]>

---
 drivers/base/memory.c |   62 +++++++++++++++++++++++++-------------------------
 1 file changed, 31 insertions(+), 31 deletions(-)

drivers/base/memory.c +31 ~~-31~~

Index: linux-2.6/drivers/base/memory.c
===================================================================
@@ -435,6 +435,37 @@ int __weak arch_get_memory_phys_device(u
 	return 0;
 }
 
+/*
+ * For now, we have a linear search to go find the appropriate
+ * memory_block corresponding to a particular phys_index. If
+ * this gets to be a real problem, we can always use a radix
+ * tree or something here.
+ *
+ * This could be made generic for all sysdev classes.
+ */
+struct memory_block *find_memory_block(struct mem_section *section)
+{
+	struct kobject *kobj;
+	struct sys_device *sysdev;
+	struct memory_block *mem;
+	char name[sizeof(MEMORY_CLASS_NAME) + 9 + 1];
+
+	/*
+	 * This only works because we know that section == sysdev->id
+	 * slightly redundant with sysdev_register()
+	 */
+	sprintf(&name[0], "%s%d", MEMORY_CLASS_NAME, __section_nr(section));
+
+	kobj = kset_find_obj(&memory_sysdev_class.kset, name);
+	if (!kobj)
+		return NULL;
+
+	sysdev = container_of(kobj, struct sys_device, kobj);
+	mem = container_of(sysdev, struct memory_block, sysdev);
+
+	return mem;
+}
+
 static int add_memory_block(int nid, struct mem_section *section,
 			unsigned long state, enum mem_add_context context)
 {

@@ -468,37 +499,6 @@ static int add_memory_block(int nid, str
 	return ret;
 }
 
-/*
- * For now, we have a linear search to go find the appropriate
- * memory_block corresponding to a particular phys_index. If
- * this gets to be a real problem, we can always use a radix
- * tree or something here.
- *
- * This could be made generic for all sysdev classes.
- */
-struct memory_block *find_memory_block(struct mem_section *section)
-{
-	struct kobject *kobj;
-	struct sys_device *sysdev;
-	struct memory_block *mem;
-	char name[sizeof(MEMORY_CLASS_NAME) + 9 + 1];
-
-	/*
-	 * This only works because we know that section == sysdev->id
-	 * slightly redundant with sysdev_register()
-	 */
-	sprintf(&name[0], "%s%d", MEMORY_CLASS_NAME, __section_nr(section));
-
-	kobj = kset_find_obj(&memory_sysdev_class.kset, name);
-	if (!kobj)
-		return NULL;
-
-	sysdev = container_of(kobj, struct sys_device, kobj);
-	mem = container_of(sysdev, struct memory_block, sysdev);
-
-	return mem;
-}
-
 int remove_memory_block(unsigned long node_id, struct mem_section *section,
 		int phys_device)
 {

KAMEZAWA Hiroyuki

Acked-by on v1 1/8

2010-07-20 07:00 UTC #2 lore raw

Re: [PATCH 1/8] v3 Move the find_memory_block() routine up

Quoted 4 lines · On Mon, 19 Jul 2010 22:51:42 -0500 Nathan Fontenot <[email protected]> wrote:

Move the find_me mory_block() routine up to avoid needing a forward declaration in subsequent patches.
Signed-off-by Nathan Fontenot <[email protected]>

Acked-by KAMEZAWA Hiroyuki <[email protected]>

Quoted 90 lines

---
 drivers/base/memory.c |   62 +++++++++++++++++++++++++-------------------------
 1 file changed, 31 insertions(+), 31 deletions(-)

Index: linux-2.6/drivers/base/memory.c
===================================================================

drivers/base/memory.c +31 ~~-32~~

@@ -435,6 +435,37 @@ int __weak arch_get_memory_phys_device(u
 	return 0;
 }
 
+/*
+ * For now, we have a linear search to go find the appropriate
+ * memory_block corresponding to a particular phys_index. If
+ * this gets to be a real problem, we can always use a radix
+ * tree or something here.
+ *
+ * This could be made generic for all sysdev classes.
+ */
+struct memory_block *find_memory_block(struct mem_section *section)
+{
+	struct kobject *kobj;
+	struct sys_device *sysdev;
+	struct memory_block *mem;
+	char name[sizeof(MEMORY_CLASS_NAME) + 9 + 1];
+
+	/*
+	 * This only works because we know that section == sysdev->id
+	 * slightly redundant with sysdev_register()
+	 */
+	sprintf(&name[0], "%s%d", MEMORY_CLASS_NAME, __section_nr(section));
+
+	kobj = kset_find_obj(&memory_sysdev_class.kset, name);
+	if (!kobj)
+		return NULL;
+
+	sysdev = container_of(kobj, struct sys_device, kobj);
+	mem = container_of(sysdev, struct memory_block, sysdev);
+
+	return mem;
+}
+
 static int add_memory_block(int nid, struct mem_section *section,
 			unsigned long state, enum mem_add_context context)
 {

@@ -468,37 +499,6 @@ static int add_memory_block(int nid, str
 	return ret;
 }
 
-/*
- * For now, we have a linear search to go find the appropriate
- * memory_block corresponding to a particular phys_index. If
- * this gets to be a real problem, we can always use a radix
- * tree or something here.
- *
- * This could be made generic for all sysdev classes.
- */
-struct memory_block *find_memory_block(struct mem_section *section)
-{
-	struct kobject *kobj;
-	struct sys_device *sysdev;
-	struct memory_block *mem;
-	char name[sizeof(MEMORY_CLASS_NAME) + 9 + 1];
-
-	/*
-	 * This only works because we know that section == sysdev->id
-	 * slightly redundant with sysdev_register()
-	 */
-	sprintf(&name[0], "%s%d", MEMORY_CLASS_NAME, __section_nr(section));
-
-	kobj = kset_find_obj(&memory_sysdev_class.kset, name);
-	if (!kobj)
-		return NULL;
-
-	sysdev = container_of(kobj, struct sys_device, kobj);
-	mem = container_of(sysdev, struct memory_block, sysdev);
-
-	return mem;
-}
-
 int remove_memory_block(unsigned long node_id, struct mem_section *section,
 		int phys_device)
 {
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Nathan Fontenot

author

2010-07-20 03:52 UTC #3 lore raw

PATCH 2/8 v3 Add new phys_index properties

In reply to Nathan Fontenot

Update the 'phys_index' properties of a memory block to include a 'start_phys_index' which is the same as the current 'phys_index' property. This also adds an 'end_phys_index' property to indicate the id of the last section in th memory block.

Signed-off-by Nathan Fontenot <[email protected]>

---
 drivers/base/memory.c  |   32 ++++++++++++++++++++++----------
 include/linux/memory.h |    3 ++-
 2 files changed, 24 insertions(+), 11 deletions(-)

drivers/base/memory.c +22 ~~-10~~

Index: linux-2.6/drivers/base/memory.c
===================================================================
@@ -109,12 +109,20 @@ unregister_memory(struct memory_block *m
  * uses.
  */
 
-static ssize_t show_mem_phys_index(struct sys_device *dev,
+static ssize_t show_mem_start_phys_index(struct sys_device *dev,
 			struct sysdev_attribute *attr, char *buf)
 {
 	struct memory_block *mem =
 		container_of(dev, struct memory_block, sysdev);
-	return sprintf(buf, "%08lx\n", mem->phys_index);
+	return sprintf(buf, "%08lx\n", mem->start_phys_index);
+}
+
+static ssize_t show_mem_end_phys_index(struct sys_device *dev,
+			struct sysdev_attribute *attr, char *buf)
+{
+	struct memory_block *mem =
+		container_of(dev, struct memory_block, sysdev);
+	return sprintf(buf, "%08lx\n", mem->end_phys_index);
 }
 
 /*

@@ -128,7 +136,7 @@ static ssize_t show_mem_removable(struct
 	struct memory_block *mem =
 		container_of(dev, struct memory_block, sysdev);
 
-	start_pfn = section_nr_to_pfn(mem->phys_index);
+	start_pfn = section_nr_to_pfn(mem->start_phys_index);
 	ret = is_mem_section_removable(start_pfn, PAGES_PER_SECTION);
 	return sprintf(buf, "%d\n", ret);
 }

@@ -191,7 +199,7 @@ memory_block_action(struct memory_block
 	int ret;
 	int old_state = mem->state;
 
-	psection = mem->phys_index;
+	psection = mem->start_phys_index;
 	first_page = pfn_to_page(psection << PFN_SECTION_SHIFT);
 
 	/*

@@ -264,7 +272,7 @@ store_mem_state(struct sys_device *dev,
 	int ret = -EINVAL;
 
 	mem = container_of(dev, struct memory_block, sysdev);
-	phys_section_nr = mem->phys_index;
+	phys_section_nr = mem->start_phys_index;
 
 	if (!present_section_nr(phys_section_nr))
 		goto out;

@@ -296,7 +304,8 @@ static ssize_t show_phys_device(struct s
 	return sprintf(buf, "%d\n", mem->phys_device);
 }
 
-static SYSDEV_ATTR(phys_index, 0444, show_mem_phys_index, NULL);
+static SYSDEV_ATTR(start_phys_index, 0444, show_mem_start_phys_index, NULL);
+static SYSDEV_ATTR(end_phys_index, 0444, show_mem_end_phys_index, NULL);
 static SYSDEV_ATTR(state, 0644, show_mem_state, store_mem_state);
 static SYSDEV_ATTR(phys_device, 0444, show_phys_device, NULL);
 static SYSDEV_ATTR(removable, 0444, show_mem_removable, NULL);

@@ -476,15 +485,17 @@ static int add_memory_block(int nid, str
 	if (!mem)
 		return -ENOMEM;
 
-	mem->phys_index = __section_nr(section);
+	mem->start_phys_index = __section_nr(section);
 	mem->state = state;
 	mutex_init(&mem->state_mutex);
-	start_pfn = section_nr_to_pfn(mem->phys_index);
+	start_pfn = section_nr_to_pfn(mem->start_phys_index);
 	mem->phys_device = arch_get_memory_phys_device(start_pfn);
 
 	ret = register_memory(mem, section);
 	if (!ret)
-		ret = mem_create_simple_file(mem, phys_index);
+		ret = mem_create_simple_file(mem, start_phys_index);
+	if (!ret)
+		ret = mem_create_simple_file(mem, end_phys_index);
 	if (!ret)
 		ret = mem_create_simple_file(mem, state);
 	if (!ret)

@@ -506,7 +517,8 @@ int remove_memory_block(unsigned long no
 
 	mem = find_memory_block(section);
 	unregister_mem_sect_under_nodes(mem);
-	mem_remove_simple_file(mem, phys_index);
+	mem_remove_simple_file(mem, start_phys_index);
+	mem_remove_simple_file(mem, end_phys_index);
 	mem_remove_simple_file(mem, state);
 	mem_remove_simple_file(mem, phys_device);
 	mem_remove_simple_file(mem, removable);

include/linux/memory.h +2 -1

Index: linux-2.6/include/linux/memory.h
===================================================================
@@ -21,7 +21,8 @@
 #include <linux/mutex.h>
 
 struct memory_block {
-	unsigned long phys_index;
+	unsigned long start_phys_index;
+	unsigned long end_phys_index;
 	unsigned long state;
 	/*
 	 * This serializes all state change requests.  It isn't

KAMEZAWA Hiroyuki

2010-07-20 07:02 UTC #4 lore raw

Re: [PATCH 2/8] v3 Add new phys_index properties

Quoted 6 lines · On Mon, 19 Jul 2010 22:52:50 -0500 Nathan Fontenot <[email protected]> wrote:

Update the 'phys_index' properties of a memory block to include a 'start_phys_index' which is the same as the current 'phys_index' property. This also adds an 'end_phys_index' property to indicate the id of the last section in th memory block.
Signed-off-by Nathan Fontenot <[email protected]>

No, please remain "phys_index" as it is. please don't rename it. IMHO, just adding end_phys_index is better.
please avoid interface change AFAP.

Do you have a problem if phys_index means start_phys_index ?

Thanks,
-Kame

Nathan Fontenot

author

2010-07-20 13:25 UTC #5 lore raw

Re: [PATCH 2/8] v3 Add new phys_index properties

In reply to Nathan Fontenot

Patch updated to keep the name of the phys_index property instead of renaming it to start_phys_index.

Signed-off-by Nathan Fontenot <[email protected]>

---
 drivers/base/memory.c  |   28 ++++++++++++++++++++--------
 include/linux/memory.h |    3 ++-
 2 files changed, 22 insertions(+), 9 deletions(-)

drivers/base/memory.c +20 -8

Index: linux-2.6/drivers/base/memory.c
===================================================================
@@ -109,12 +109,20 @@ unregister_memory(struct memory_block *m
  * uses.
  */
 
-static ssize_t show_mem_phys_index(struct sys_device *dev,
+static ssize_t show_mem_start_phys_index(struct sys_device *dev,
 			struct sysdev_attribute *attr, char *buf)
 {
 	struct memory_block *mem =
 		container_of(dev, struct memory_block, sysdev);
-	return sprintf(buf, "%08lx\n", mem->phys_index);
+	return sprintf(buf, "%08lx\n", mem->start_phys_index);
+}
+
+static ssize_t show_mem_end_phys_index(struct sys_device *dev,
+			struct sysdev_attribute *attr, char *buf)
+{
+	struct memory_block *mem =
+		container_of(dev, struct memory_block, sysdev);
+	return sprintf(buf, "%08lx\n", mem->end_phys_index);
 }
 
 /*

@@ -128,7 +136,7 @@ static ssize_t show_mem_removable(struct
 	struct memory_block *mem =
 		container_of(dev, struct memory_block, sysdev);
 
-	start_pfn = section_nr_to_pfn(mem->phys_index);
+	start_pfn = section_nr_to_pfn(mem->start_phys_index);
 	ret = is_mem_section_removable(start_pfn, PAGES_PER_SECTION);
 	return sprintf(buf, "%d\n", ret);
 }

@@ -191,7 +199,7 @@ memory_block_action(struct memory_block
 	int ret;
 	int old_state = mem->state;
 
-	psection = mem->phys_index;
+	psection = mem->start_phys_index;
 	first_page = pfn_to_page(psection << PFN_SECTION_SHIFT);
 
 	/*

@@ -264,7 +272,7 @@ store_mem_state(struct sys_device *dev,
 	int ret = -EINVAL;
 
 	mem = container_of(dev, struct memory_block, sysdev);
-	phys_section_nr = mem->phys_index;
+	phys_section_nr = mem->start_phys_index;
 
 	if (!present_section_nr(phys_section_nr))
 		goto out;

@@ -296,7 +304,8 @@ static ssize_t show_phys_device(struct s
 	return sprintf(buf, "%d\n", mem->phys_device);
 }
 
-static SYSDEV_ATTR(phys_index, 0444, show_mem_phys_index, NULL);
+static SYSDEV_ATTR(phys_index, 0444, show_mem_start_phys_index, NULL);
+static SYSDEV_ATTR(end_phys_index, 0444, show_mem_end_phys_index, NULL);
 static SYSDEV_ATTR(state, 0644, show_mem_state, store_mem_state);
 static SYSDEV_ATTR(phys_device, 0444, show_phys_device, NULL);
 static SYSDEV_ATTR(removable, 0444, show_mem_removable, NULL);

@@ -476,16 +485,18 @@ static int add_memory_block(int nid, str
 	if (!mem)
 		return -ENOMEM;
 
-	mem->phys_index = __section_nr(section);
+	mem->start_phys_index = __section_nr(section);
 	mem->state = state;
 	mutex_init(&mem->state_mutex);
-	start_pfn = section_nr_to_pfn(mem->phys_index);
+	start_pfn = section_nr_to_pfn(mem->start_phys_index);
 	mem->phys_device = arch_get_memory_phys_device(start_pfn);
 
 	ret = register_memory(mem, section);
 	if (!ret)
 		ret = mem_create_simple_file(mem, phys_index);
 	if (!ret)
+		ret = mem_create_simple_file(mem, end_phys_index);
+	if (!ret)
 		ret = mem_create_simple_file(mem, state);
 	if (!ret)
 		ret = mem_create_simple_file(mem, phys_device);

@@ -507,6 +518,7 @@ int remove_memory_block(unsigned long no
 	mem = find_memory_block(section);
 	unregister_mem_sect_under_nodes(mem);
 	mem_remove_simple_file(mem, phys_index);
+	mem_remove_simple_file(mem, end_phys_index);
 	mem_remove_simple_file(mem, state);
 	mem_remove_simple_file(mem, phys_device);
 	mem_remove_simple_file(mem, removable);

include/linux/memory.h +2 -1

Index: linux-2.6/include/linux/memory.h
===================================================================
@@ -21,7 +21,8 @@
 #include <linux/mutex.h>
 
 struct memory_block {
-	unsigned long phys_index;
+	unsigned long start_phys_index;
+	unsigned long end_phys_index;
 	unsigned long state;
 	/*
 	 * This serializes all state change requests.  It isn't

Dave Hansen

2010-07-20 19:10 UTC #6 lore raw

Re: [PATCH 2/8] v3 Add new phys_index properties

Quoted 7 lines · Nathan Fontenot

Update the 'phys_index' properties of a memory block to include a 'start_phys_index' which is the same as the current 'phys_index' property. This also adds an 'end_phys_index' property to indicate the id of the last section in th memory block.
Patch updated to keep the name of the phys_index property instead of renaming it to start_phys_index.

KAME is right on this. We should keep the old one if at all possible.

The only other thing we might want to do is move 'phys_index' to 'start_phys_index', and make a new 'phys_index' that does a WARN_ONCE(), gives a deprecated warning, then calls the new 'start_phys_index' code.

So, basically make the new, more clear name, but keep the old one for a while and deprecate it. Maybe we could get away with removing it in ten years. :)

-- Dave

Nathan Fontenot

author

2010-07-20 03:54 UTC #7 lore raw

PATCH 3/8 v3 Add section count to memory_block

In reply to Nathan Fontenot

Add a section count property to the memory_block struct to track the number of memory sections that have been added/removed from a emory block.

Signed-off-by Nathan Fontenot <[email protected]>

---
 drivers/base/memory.c  |   19 ++++++++++++-------
 include/linux/memory.h |    2 ++
 2 files changed, 14 insertions(+), 7 deletions(-)

drivers/base/memory.c +12 -7

Index: linux-2.6/drivers/base/memory.c
===================================================================
@@ -487,6 +487,7 @@ static int add_memory_block(int nid, str
 
 	mem->start_phys_index = __section_nr(section);
 	mem->state = state;
+	atomic_inc(&mem->section_count);
 	mutex_init(&mem->state_mutex);
 	start_pfn = section_nr_to_pfn(mem->start_phys_index);
 	mem->phys_device = arch_get_memory_phys_device(start_pfn);

@@ -516,13 +517,17 @@ int remove_memory_block(unsigned long no
 	struct memory_block *mem;
 
 	mem = find_memory_block(section);
-	unregister_mem_sect_under_nodes(mem);
-	mem_remove_simple_file(mem, start_phys_index);
-	mem_remove_simple_file(mem, end_phys_index);
-	mem_remove_simple_file(mem, state);
-	mem_remove_simple_file(mem, phys_device);
-	mem_remove_simple_file(mem, removable);
-	unregister_memory(mem, section);
+	atomic_dec(&mem->section_count);
+
+	if (atomic_read(&mem->section_count) == 0) {
+		unregister_mem_sect_under_nodes(mem);
+		mem_remove_simple_file(mem, start_phys_index);
+		mem_remove_simple_file(mem, end_phys_index);
+		mem_remove_simple_file(mem, state);
+		mem_remove_simple_file(mem, phys_device);
+		mem_remove_simple_file(mem, removable);
+		unregister_memory(mem, section);
+	}
 
 	return 0;
 }

include/linux/memory.h +2 -0

Index: linux-2.6/include/linux/memory.h
===================================================================
@@ -19,11 +19,13 @@
 #include <linux/node.h>
 #include <linux/compiler.h>
 #include <linux/mutex.h>
+#include <asm/atomic.h>
 
 struct memory_block {
 	unsigned long start_phys_index;
 	unsigned long end_phys_index;
 	unsigned long state;
+	atomic_t section_count;
 	/*
 	 * This serializes all state change requests.  It isn't
 	 * held during creation because the control files are

KAMEZAWA Hiroyuki

2010-07-20 07:06 UTC #8 lore raw

Re: [PATCH 3/8] v3 Add section count to memory_block

Quoted 25 lines · On Mon, 19 Jul 2010 22:53:58 -0500 Nathan Fontenot <[email protected]> wrote:

Add a section count property to the memory_block struct to track the number of memory sections that have been added/removed from a emory block.
Signed-off-by Nathan Fontenot <[email protected]>
---
 drivers/base/memory.c  |   19 ++++++++++++-------
 include/linux/memory.h |    2 ++
 2 files changed, 14 insertions(+), 7 deletions(-)
Index: linux-2.6/drivers/base/memory.c
===================================================================
drivers/base/memory.c +1 -0
@@ -487,6 +487,7 @@ static int add_memory_block(int nid, str
 
 	mem->start_phys_index = __section_nr(section);
 	mem->state = state;
+	atomic_inc(&mem->section_count);
 	mutex_init(&mem->state_mutex);
 	start_pfn = section_nr_to_pfn(mem->start_phys_index);
 	mem->phys_device = arch_get_memory_phys_device(start_pfn);
@@ -516,13 +517,17 @@ int remove_memory_block(unsigned long no
 	struct memory_block *mem;
 
 	mem = find_memory_block(section);

drivers/base/memory.c int remove_memory_block(unsigned long no · line 522

Quoted 10 lines

drivers/base/memory.c +3 -7

-	unregister_mem_sect_under_nodes(mem);
-	mem_remove_simple_file(mem, start_phys_index);
-	mem_remove_simple_file(mem, end_phys_index);
-	mem_remove_simple_file(mem, state);
-	mem_remove_simple_file(mem, phys_device);
-	mem_remove_simple_file(mem, removable);
-	unregister_memory(mem, section);
+	atomic_dec(&mem->section_count);
+
+	if (atomic_read(&mem->section_count) == 0) {

We use atomic_dec_and_test() in usual.

Otherwise, I don't see other problems in other part. Please fix this nitpick.

Regards,
-Kame

Nathan Fontenot

author

2010-07-20 13:26 UTC #9 lore raw

Re: [PATCH 3/8] v3 Add section count to memory_block

In reply to Nathan Fontenot

Add a section count property to the memory_block struct to track the number of memory sections that have been added/removed from a memory block. Updated to use atomic_dec_and_test().

Signed-off-by Nathan Fontenot <[email protected]>

---
 drivers/base/memory.c  |   18 +++++++++++-------
 include/linux/memory.h |    2 ++
 2 files changed, 13 insertions(+), 7 deletions(-)

drivers/base/memory.c +11 -7

Index: linux-2.6/drivers/base/memory.c
===================================================================
@@ -487,6 +487,7 @@ static int add_memory_block(int nid, str
 
 	mem->start_phys_index = __section_nr(section);
 	mem->state = state;
+	atomic_inc(&mem->section_count);
 	mutex_init(&mem->state_mutex);
 	start_pfn = section_nr_to_pfn(mem->start_phys_index);
 	mem->phys_device = arch_get_memory_phys_device(start_pfn);

@@ -516,13 +517,16 @@ int remove_memory_block(unsigned long no
 	struct memory_block *mem;
 
 	mem = find_memory_block(section);
-	unregister_mem_sect_under_nodes(mem);
-	mem_remove_simple_file(mem, phys_index);
-	mem_remove_simple_file(mem, end_phys_index);
-	mem_remove_simple_file(mem, state);
-	mem_remove_simple_file(mem, phys_device);
-	mem_remove_simple_file(mem, removable);
-	unregister_memory(mem, section);
+
+	if (atomic_dec_and_test(&mem->section_count)) {
+		unregister_mem_sect_under_nodes(mem);
+		mem_remove_simple_file(mem, phys_index);
+		mem_remove_simple_file(mem, end_phys_index);
+		mem_remove_simple_file(mem, state);
+		mem_remove_simple_file(mem, phys_device);
+		mem_remove_simple_file(mem, removable);
+		unregister_memory(mem, section);
+	}
 
 	return 0;
 }

include/linux/memory.h +2 -0

Index: linux-2.6/include/linux/memory.h
===================================================================
@@ -19,11 +19,13 @@
 #include <linux/node.h>
 #include <linux/compiler.h>
 #include <linux/mutex.h>
+#include <asm/atomic.h>
 
 struct memory_block {
 	unsigned long start_phys_index;
 	unsigned long end_phys_index;
 	unsigned long state;
+	atomic_t section_count;
 	/*
 	 * This serializes all state change requests.  It isn't
 	 * held during creation because the control files are

Nathan Fontenot

author

2010-07-20 03:55 UTC #10 lore raw

PATCH 4/8 v3 Allow memory_block to span multiple memory sections

In reply to Nathan Fontenot

Update the memory sysfs code that each sysfs memory directory is now considered a memory block that can contain multiple memory sections per memory block. The default size of each memory block is SECTION_SIZE_BITS to maintain the current behavior of having a single memory section per memory block (i.e. one sysfs directory per memory section).

For architectures that want to have memory blocks span multiple memory sections they need only define their own memory_block_size_bytes() routine.

Signed-off-by Nathan Fontenot <[email protected]>

---
 drivers/base/memory.c |  141 ++++++++++++++++++++++++++++++++++----------------
 1 file changed, 98 insertions(+), 43 deletions(-)

drivers/base/memory.c +98 ~~-43~~

Index: linux-2.6/drivers/base/memory.c
===================================================================
@@ -28,6 +28,14 @@
 #include <asm/uaccess.h>
 
 #define MEMORY_CLASS_NAME	"memory"
+#define MIN_MEMORY_BLOCK_SIZE	(1 << SECTION_SIZE_BITS)
+
+static int sections_per_block;
+
+static inline int base_memory_block_id(int section_nr)
+{
+	return (section_nr / sections_per_block) * sections_per_block;
+}
 
 static struct sysdev_class memory_sysdev_class = {
 	.name = MEMORY_CLASS_NAME,

@@ -82,22 +90,21 @@ EXPORT_SYMBOL(unregister_memory_isolate_
  * register_memory - Setup a sysfs device for a memory block
  */
 static
-int register_memory(struct memory_block *memory, struct mem_section *section)
+int register_memory(struct memory_block *memory)
 {
 	int error;
 
 	memory->sysdev.cls = &memory_sysdev_class;
-	memory->sysdev.id = __section_nr(section);
+	memory->sysdev.id = memory->start_phys_index;
 
 	error = sysdev_register(&memory->sysdev);
 	return error;
 }
 
 static void
-unregister_memory(struct memory_block *memory, struct mem_section *section)
+unregister_memory(struct memory_block *memory)
 {
 	BUG_ON(memory->sysdev.cls != &memory_sysdev_class);
-	BUG_ON(memory->sysdev.id != __section_nr(section));
 
 	/* drop the ref. we got in remove_memory_block() */
 	kobject_put(&memory->sysdev.kobj);

@@ -131,13 +138,16 @@ static ssize_t show_mem_end_phys_index(s
 static ssize_t show_mem_removable(struct sys_device *dev,
 			struct sysdev_attribute *attr, char *buf)
 {
-	unsigned long start_pfn;
-	int ret;
+	unsigned long i, pfn;
+	int ret = 1;
 	struct memory_block *mem =
 		container_of(dev, struct memory_block, sysdev);
 
-	start_pfn = section_nr_to_pfn(mem->start_phys_index);
-	ret = is_mem_section_removable(start_pfn, PAGES_PER_SECTION);
+	for (i = mem->start_phys_index; i <= mem->end_phys_index; i++) {
+		pfn = section_nr_to_pfn(i);
+		ret &= is_mem_section_removable(pfn, PAGES_PER_SECTION);
+	}
+
 	return sprintf(buf, "%d\n", ret);
 }

@@ -190,17 +200,14 @@ int memory_isolate_notify(unsigned long
  * OK to have direct references to sparsemem variables in here.
  */
 static int
-memory_block_action(struct memory_block *mem, unsigned long action)
+memory_section_action(unsigned long phys_index, unsigned long action)
 {
 	int i;
-	unsigned long psection;
 	unsigned long start_pfn, start_paddr;
 	struct page *first_page;
 	int ret;
-	int old_state = mem->state;
 
-	psection = mem->start_phys_index;
-	first_page = pfn_to_page(psection << PFN_SECTION_SHIFT);
+	first_page = pfn_to_page(phys_index << PFN_SECTION_SHIFT);
 
 	/*
 	 * The probe routines leave the pages reserved, just

@@ -213,8 +220,8 @@ memory_block_action(struct memory_block
 				continue;
 
 			printk(KERN_WARNING "section number %ld page number %d "
-				"not reserved, was it already online? \n",
-				psection, i);
+				"not reserved, was it already online?\n",
+				phys_index, i);
 			return -EBUSY;
 		}
 	}

@@ -225,18 +232,13 @@ memory_block_action(struct memory_block
 			ret = online_pages(start_pfn, PAGES_PER_SECTION);
 			break;
 		case MEM_OFFLINE:
-			mem->state = MEM_GOING_OFFLINE;
 			start_paddr = page_to_pfn(first_page) << PAGE_SHIFT;
 			ret = remove_memory(start_paddr,
 					    PAGES_PER_SECTION << PAGE_SHIFT);
-			if (ret) {
-				mem->state = old_state;
-				break;
-			}
 			break;
 		default:
-			WARN(1, KERN_WARNING "%s(%p, %ld) unknown action: %ld\n",
-					__func__, mem, action, action);
+			WARN(1, KERN_WARNING "%s(%ld, %ld) unknown action: "
+			     "%ld\n", __func__, phys_index, action, action);
 			ret = -EINVAL;
 	}

@@ -246,7 +248,7 @@ memory_block_action(struct memory_block
 static int memory_block_change_state(struct memory_block *mem,
 		unsigned long to_state, unsigned long from_state_req)
 {
-	int ret = 0;
+	int i, ret = 0;
 	mutex_lock(&mem->state_mutex);
 
 	if (mem->state != from_state_req) {

@@ -254,8 +256,21 @@ static int memory_block_change_state(str
 		goto out;
 	}
 
-	ret = memory_block_action(mem, to_state);
-	if (!ret)
+	if (to_state == MEM_OFFLINE)
+		mem->state = MEM_GOING_OFFLINE;
+
+	for (i = mem->start_phys_index; i <= mem->end_phys_index; i++) {
+		ret = memory_section_action(i, to_state);
+		if (ret)
+			break;
+	}
+
+	if (ret) {
+		for (i = mem->start_phys_index; i <= mem->end_phys_index; i++)
+			memory_section_action(i, from_state_req);
+
+		mem->state = from_state_req;
+	} else
 		mem->state = to_state;
 
 out:

@@ -268,20 +283,15 @@ store_mem_state(struct sys_device *dev,
 		struct sysdev_attribute *attr, const char *buf, size_t count)
 {
 	struct memory_block *mem;
-	unsigned int phys_section_nr;
 	int ret = -EINVAL;
 
 	mem = container_of(dev, struct memory_block, sysdev);
-	phys_section_nr = mem->start_phys_index;
-
-	if (!present_section_nr(phys_section_nr))
-		goto out;
 
 	if (!strncmp(buf, "online", min((int)count, 6)))
 		ret = memory_block_change_state(mem, MEM_ONLINE, MEM_OFFLINE);
 	else if(!strncmp(buf, "offline", min((int)count, 7)))
 		ret = memory_block_change_state(mem, MEM_OFFLINE, MEM_ONLINE);
-out:
+
 	if (ret)
 		return ret;
 	return count;

@@ -458,12 +468,13 @@ struct memory_block *find_memory_block(s
 	struct sys_device *sysdev;
 	struct memory_block *mem;
 	char name[sizeof(MEMORY_CLASS_NAME) + 9 + 1];
+	int block_id = base_memory_block_id(__section_nr(section));
 
 	/*
 	 * This only works because we know that section == sysdev->id
 	 * slightly redundant with sysdev_register()
 	 */
-	sprintf(&name[0], "%s%d", MEMORY_CLASS_NAME, __section_nr(section));
+	sprintf(&name[0], "%s%d", MEMORY_CLASS_NAME, block_id);
 
 	kobj = kset_find_obj(&memory_sysdev_class.kset, name);
 	if (!kobj)

@@ -475,24 +486,26 @@ struct memory_block *find_memory_block(s
 	return mem;
 }
 
-static int add_memory_block(int nid, struct mem_section *section,
-			unsigned long state, enum mem_add_context context)
+static int init_memory_block(struct memory_block **memory,
+			     struct mem_section *section, unsigned long state)
 {
-	struct memory_block *mem = kzalloc(sizeof(*mem), GFP_KERNEL);
+	struct memory_block *mem;
 	unsigned long start_pfn;
 	int ret = 0;
 
+	mem = kzalloc(sizeof(*mem), GFP_KERNEL);
 	if (!mem)
 		return -ENOMEM;
 
-	mem->start_phys_index = __section_nr(section);
+	mem->start_phys_index = base_memory_block_id(__section_nr(section));
+	mem->end_phys_index = mem->start_phys_index + sections_per_block - 1;
 	mem->state = state;
 	atomic_inc(&mem->section_count);
 	mutex_init(&mem->state_mutex);
 	start_pfn = section_nr_to_pfn(mem->start_phys_index);
 	mem->phys_device = arch_get_memory_phys_device(start_pfn);
 
-	ret = register_memory(mem, section);
+	ret = register_memory(mem);
 	if (!ret)
 		ret = mem_create_simple_file(mem, start_phys_index);
 	if (!ret)

@@ -503,8 +516,27 @@ static int add_memory_block(int nid, str
 		ret = mem_create_simple_file(mem, phys_device);
 	if (!ret)
 		ret = mem_create_simple_file(mem, removable);
+
+	*memory = mem;
+	return ret;
+}
+
+static int add_memory_section(int nid, struct mem_section *section,
+			unsigned long state, enum mem_add_context context)
+{
+	struct memory_block *mem;
+	int ret = 0;
+
+	mem = find_memory_block(section);
+	if (mem) {
+		atomic_inc(&mem->section_count);
+		kobject_put(&mem->sysdev.kobj);
+	} else
+		ret = init_memory_block(&mem, section, state);
+
 	if (!ret) {
-		if (context == HOTPLUG)
+		if (context == HOTPLUG &&
+		    atomic_read(&mem->section_count) == sections_per_block)
 			ret = register_mem_sect_under_node(mem, nid);
 	}

@@ -526,8 +558,9 @@ int remove_memory_block(unsigned long no
 		mem_remove_simple_file(mem, state);
 		mem_remove_simple_file(mem, phys_device);
 		mem_remove_simple_file(mem, removable);
-		unregister_memory(mem, section);
-	}
+		unregister_memory(mem);
+	} else
+		kobject_put(&mem->sysdev.kobj);
 
 	return 0;
 }

@@ -538,7 +571,7 @@ int remove_memory_block(unsigned long no
  */
 int register_new_memory(int nid, struct mem_section *section)
 {
-	return add_memory_block(nid, section, MEM_OFFLINE, HOTPLUG);
+	return add_memory_section(nid, section, MEM_OFFLINE, HOTPLUG);
 }
 
 int unregister_memory_section(struct mem_section *section)

@@ -549,6 +582,24 @@ int unregister_memory_section(struct mem
 	return remove_memory_block(0, section, 0);
 }
 
+u32 __weak memory_block_size_bytes(void)
+{
+	return MIN_MEMORY_BLOCK_SIZE;
+}
+
+static u32 get_memory_block_size(void)
+{
+	u32 block_sz;
+
+	block_sz = memory_block_size_bytes();
+
+	/* Validate blk_sz is a power of 2 and not less than section size */
+	if ((block_sz & (block_sz - 1)) || (block_sz < MIN_MEMORY_BLOCK_SIZE))
+		block_sz = MIN_MEMORY_BLOCK_SIZE;
+
+	return block_sz;
+}
+
 /*
  * Initialize the sysfs support for memory devices...
  */

@@ -557,12 +608,16 @@ int __init memory_dev_init(void)
 	unsigned int i;
 	int ret;
 	int err;
+	int block_sz;
 
 	memory_sysdev_class.kset.uevent_ops = &memory_uevent_ops;
 	ret = sysdev_class_register(&memory_sysdev_class);
 	if (ret)
 		goto out;
 
+	block_sz = get_memory_block_size();
+	sections_per_block = block_sz / MIN_MEMORY_BLOCK_SIZE;
+
 	/*
 	 * Create entries for memory sections that were found
 	 * during boot and have been initialized

@@ -570,8 +625,8 @@ int __init memory_dev_init(void)
 	for (i = 0; i < NR_MEM_SECTIONS; i++) {
 		if (!present_section_nr(i))
 			continue;
-		err = add_memory_block(0, __nr_to_section(i), MEM_ONLINE,
-				       BOOT);
+		err = add_memory_section(0, __nr_to_section(i), MEM_ONLINE,
+					 BOOT);
 		if (!ret)
 			ret = err;
 	}

KAMEZAWA Hiroyuki

2010-07-20 07:20 UTC #11 lore raw

Re: [PATCH 4/8] v3 Allow memory_block to span multiple memory sections

Quoted 36 lines · On Mon, 19 Jul 2010 22:55:08 -0500 Nathan Fontenot <[email protected]> wrote:

Update the memory sysfs code that each sysfs memory directory is now considered a memory block that can contain multiple memory sections per memory block. The default size of each memory block is SECTION_SIZE_BITS to maintain the current behavior of having a single memory section per memory block (i.e. one sysfs directory per memory section).
For architectures that want to have memory blocks span multiple memory sections they need only define their own memory_block_size_bytes() routine.
Signed-off-by Nathan Fontenot <[email protected]>
---
 drivers/base/memory.c |  141 ++++++++++++++++++++++++++++++++++----------------
 1 file changed, 98 insertions(+), 43 deletions(-)
Index: linux-2.6/drivers/base/memory.c
===================================================================
drivers/base/memory.c +8 -0
@@ -28,6 +28,14 @@
 #include <asm/uaccess.h>
 
 #define MEMORY_CLASS_NAME	"memory"
+#define MIN_MEMORY_BLOCK_SIZE	(1 << SECTION_SIZE_BITS)
+
+static int sections_per_block;
+
+static inline int base_memory_block_id(int section_nr)
+{
+	return (section_nr / sections_per_block) * sections_per_block;
+}
 
 static struct sysdev_class memory_sysdev_class = {
 	.name = MEMORY_CLASS_NAME,
@@ -82,22 +90,21 @@ EXPORT_SYMBOL(unregister_memory_isolate_
  * register_memory - Setup a sysfs device for a memory block

drivers/base/memory.c EXPORT_SYMBOL(unregister_memory_isolate_ · line 98

Quoted 10 lines

drivers/base/memory.c +2 -2

  */
 static
-int register_memory(struct memory_block *memory, struct mem_section *section)
+int register_memory(struct memory_block *memory)
 {
 	int error;
 
 	memory->sysdev.cls = &memory_sysdev_class;
-	memory->sysdev.id = __section_nr(section);
+	memory->sysdev.id = memory->start_phys_index;

I'm curious that this memory->start_phys_index can't overflow ? sysdev.id is 32bit.

Thanks,
-Kame

Nathan Fontenot

author

2010-07-20 13:29 UTC #12 lore raw

Re: [PATCH 4/8] v3 Allow memory_block to span multiple memory sections

In reply to Nathan Fontenot

For architectures that want to have memory blocks span multiple memory sections they need only define their own memory_block_size_bytes() routine.

Patch refreshed to apply cleanly with previous two patch updates.

Signed-off-by Nathan Fontenot <[email protected]>

---
 drivers/base/memory.c |  141 ++++++++++++++++++++++++++++++++++----------------
 1 file changed, 98 insertions(+), 43 deletions(-)

drivers/base/memory.c +98 ~~-43~~

Index: linux-2.6/drivers/base/memory.c
===================================================================
@@ -28,6 +28,14 @@
 #include <asm/uaccess.h>
 
 #define MEMORY_CLASS_NAME	"memory"
+#define MIN_MEMORY_BLOCK_SIZE	(1 << SECTION_SIZE_BITS)
+
+static int sections_per_block;
+
+static inline int base_memory_block_id(int section_nr)
+{
+	return (section_nr / sections_per_block) * sections_per_block;
+}
 
 static struct sysdev_class memory_sysdev_class = {
 	.name = MEMORY_CLASS_NAME,

@@ -82,22 +90,21 @@ EXPORT_SYMBOL(unregister_memory_isolate_
  * register_memory - Setup a sysfs device for a memory block
  */
 static
-int register_memory(struct memory_block *memory, struct mem_section *section)
+int register_memory(struct memory_block *memory)
 {
 	int error;
 
 	memory->sysdev.cls = &memory_sysdev_class;
-	memory->sysdev.id = __section_nr(section);
+	memory->sysdev.id = memory->start_phys_index;
 
 	error = sysdev_register(&memory->sysdev);
 	return error;
 }
 
 static void
-unregister_memory(struct memory_block *memory, struct mem_section *section)
+unregister_memory(struct memory_block *memory)
 {
 	BUG_ON(memory->sysdev.cls != &memory_sysdev_class);
-	BUG_ON(memory->sysdev.id != __section_nr(section));
 
 	/* drop the ref. we got in remove_memory_block() */
 	kobject_put(&memory->sysdev.kobj);

@@ -131,13 +138,16 @@ static ssize_t show_mem_end_phys_index(s
 static ssize_t show_mem_removable(struct sys_device *dev,
 			struct sysdev_attribute *attr, char *buf)
 {
-	unsigned long start_pfn;
-	int ret;
+	unsigned long i, pfn;
+	int ret = 1;
 	struct memory_block *mem =
 		container_of(dev, struct memory_block, sysdev);
 
-	start_pfn = section_nr_to_pfn(mem->start_phys_index);
-	ret = is_mem_section_removable(start_pfn, PAGES_PER_SECTION);
+	for (i = mem->start_phys_index; i <= mem->end_phys_index; i++) {
+		pfn = section_nr_to_pfn(i);
+		ret &= is_mem_section_removable(pfn, PAGES_PER_SECTION);
+	}
+
 	return sprintf(buf, "%d\n", ret);
 }

@@ -190,17 +200,14 @@ int memory_isolate_notify(unsigned long
  * OK to have direct references to sparsemem variables in here.
  */
 static int
-memory_block_action(struct memory_block *mem, unsigned long action)
+memory_section_action(unsigned long phys_index, unsigned long action)
 {
 	int i;
-	unsigned long psection;
 	unsigned long start_pfn, start_paddr;
 	struct page *first_page;
 	int ret;
-	int old_state = mem->state;
 
-	psection = mem->start_phys_index;
-	first_page = pfn_to_page(psection << PFN_SECTION_SHIFT);
+	first_page = pfn_to_page(phys_index << PFN_SECTION_SHIFT);
 
 	/*
 	 * The probe routines leave the pages reserved, just

@@ -213,8 +220,8 @@ memory_block_action(struct memory_block
 				continue;
 
 			printk(KERN_WARNING "section number %ld page number %d "
-				"not reserved, was it already online? \n",
-				psection, i);
+				"not reserved, was it already online?\n",
+				phys_index, i);
 			return -EBUSY;
 		}
 	}

@@ -225,18 +232,13 @@ memory_block_action(struct memory_block
 			ret = online_pages(start_pfn, PAGES_PER_SECTION);
 			break;
 		case MEM_OFFLINE:
-			mem->state = MEM_GOING_OFFLINE;
 			start_paddr = page_to_pfn(first_page) << PAGE_SHIFT;
 			ret = remove_memory(start_paddr,
 					    PAGES_PER_SECTION << PAGE_SHIFT);
-			if (ret) {
-				mem->state = old_state;
-				break;
-			}
 			break;
 		default:
-			WARN(1, KERN_WARNING "%s(%p, %ld) unknown action: %ld\n",
-					__func__, mem, action, action);
+			WARN(1, KERN_WARNING "%s(%ld, %ld) unknown action: "
+			     "%ld\n", __func__, phys_index, action, action);
 			ret = -EINVAL;
 	}

@@ -246,7 +248,7 @@ memory_block_action(struct memory_block
 static int memory_block_change_state(struct memory_block *mem,
 		unsigned long to_state, unsigned long from_state_req)
 {
-	int ret = 0;
+	int i, ret = 0;
 	mutex_lock(&mem->state_mutex);
 
 	if (mem->state != from_state_req) {

@@ -254,8 +256,21 @@ static int memory_block_change_state(str
 		goto out;
 	}
 
-	ret = memory_block_action(mem, to_state);
-	if (!ret)
+	if (to_state == MEM_OFFLINE)
+		mem->state = MEM_GOING_OFFLINE;
+
+	for (i = mem->start_phys_index; i <= mem->end_phys_index; i++) {
+		ret = memory_section_action(i, to_state);
+		if (ret)
+			break;
+	}
+
+	if (ret) {
+		for (i = mem->start_phys_index; i <= mem->end_phys_index; i++)
+			memory_section_action(i, from_state_req);
+
+		mem->state = from_state_req;
+	} else
 		mem->state = to_state;
 
 out:

@@ -268,20 +283,15 @@ store_mem_state(struct sys_device *dev,
 		struct sysdev_attribute *attr, const char *buf, size_t count)
 {
 	struct memory_block *mem;
-	unsigned int phys_section_nr;
 	int ret = -EINVAL;
 
 	mem = container_of(dev, struct memory_block, sysdev);
-	phys_section_nr = mem->start_phys_index;
-
-	if (!present_section_nr(phys_section_nr))
-		goto out;
 
 	if (!strncmp(buf, "online", min((int)count, 6)))
 		ret = memory_block_change_state(mem, MEM_ONLINE, MEM_OFFLINE);
 	else if(!strncmp(buf, "offline", min((int)count, 7)))
 		ret = memory_block_change_state(mem, MEM_OFFLINE, MEM_ONLINE);
-out:
+
 	if (ret)
 		return ret;
 	return count;

@@ -458,12 +468,13 @@ struct memory_block *find_memory_block(s
 	struct sys_device *sysdev;
 	struct memory_block *mem;
 	char name[sizeof(MEMORY_CLASS_NAME) + 9 + 1];
+	int block_id = base_memory_block_id(__section_nr(section));
 
 	/*
 	 * This only works because we know that section == sysdev->id
 	 * slightly redundant with sysdev_register()
 	 */
-	sprintf(&name[0], "%s%d", MEMORY_CLASS_NAME, __section_nr(section));
+	sprintf(&name[0], "%s%d", MEMORY_CLASS_NAME, block_id);
 
 	kobj = kset_find_obj(&memory_sysdev_class.kset, name);
 	if (!kobj)

@@ -475,24 +486,26 @@ struct memory_block *find_memory_block(s
 	return mem;
 }
 
-static int add_memory_block(int nid, struct mem_section *section,
-			unsigned long state, enum mem_add_context context)
+static int init_memory_block(struct memory_block **memory,
+			     struct mem_section *section, unsigned long state)
 {
-	struct memory_block *mem = kzalloc(sizeof(*mem), GFP_KERNEL);
+	struct memory_block *mem;
 	unsigned long start_pfn;
 	int ret = 0;
 
+	mem = kzalloc(sizeof(*mem), GFP_KERNEL);
 	if (!mem)
 		return -ENOMEM;
 
-	mem->start_phys_index = __section_nr(section);
+	mem->start_phys_index = base_memory_block_id(__section_nr(section));
+	mem->end_phys_index = mem->start_phys_index + sections_per_block - 1;
 	mem->state = state;
 	atomic_inc(&mem->section_count);
 	mutex_init(&mem->state_mutex);
 	start_pfn = section_nr_to_pfn(mem->start_phys_index);
 	mem->phys_device = arch_get_memory_phys_device(start_pfn);
 
-	ret = register_memory(mem, section);
+	ret = register_memory(mem);
 	if (!ret)
 		ret = mem_create_simple_file(mem, phys_index);
 	if (!ret)

@@ -503,8 +516,27 @@ static int add_memory_block(int nid, str
 		ret = mem_create_simple_file(mem, phys_device);
 	if (!ret)
 		ret = mem_create_simple_file(mem, removable);
+
+	*memory = mem;
+	return ret;
+}
+
+static int add_memory_section(int nid, struct mem_section *section,
+			unsigned long state, enum mem_add_context context)
+{
+	struct memory_block *mem;
+	int ret = 0;
+
+	mem = find_memory_block(section);
+	if (mem) {
+		atomic_inc(&mem->section_count);
+		kobject_put(&mem->sysdev.kobj);
+	} else
+		ret = init_memory_block(&mem, section, state);
+
 	if (!ret) {
-		if (context == HOTPLUG)
+		if (context == HOTPLUG &&
+		    atomic_read(&mem->section_count) == sections_per_block)
 			ret = register_mem_sect_under_node(mem, nid);
 	}

@@ -525,8 +557,9 @@ int remove_memory_block(unsigned long no
 		mem_remove_simple_file(mem, state);
 		mem_remove_simple_file(mem, phys_device);
 		mem_remove_simple_file(mem, removable);
-		unregister_memory(mem, section);
-	}
+		unregister_memory(mem);
+	} else
+		kobject_put(&mem->sysdev.kobj);
 
 	return 0;
 }

@@ -537,7 +570,7 @@ int remove_memory_block(unsigned long no
  */
 int register_new_memory(int nid, struct mem_section *section)
 {
-	return add_memory_block(nid, section, MEM_OFFLINE, HOTPLUG);
+	return add_memory_section(nid, section, MEM_OFFLINE, HOTPLUG);
 }
 
 int unregister_memory_section(struct mem_section *section)

@@ -548,6 +581,24 @@ int unregister_memory_section(struct mem
 	return remove_memory_block(0, section, 0);
 }
 
+u32 __weak memory_block_size_bytes(void)
+{
+	return MIN_MEMORY_BLOCK_SIZE;
+}
+
+static u32 get_memory_block_size(void)
+{
+	u32 block_sz;
+
+	block_sz = memory_block_size_bytes();
+
+	/* Validate blk_sz is a power of 2 and not less than section size */
+	if ((block_sz & (block_sz - 1)) || (block_sz < MIN_MEMORY_BLOCK_SIZE))
+		block_sz = MIN_MEMORY_BLOCK_SIZE;
+
+	return block_sz;
+}
+
 /*
  * Initialize the sysfs support for memory devices...
  */

@@ -556,12 +607,16 @@ int __init memory_dev_init(void)
 	unsigned int i;
 	int ret;
 	int err;
+	int block_sz;
 
 	memory_sysdev_class.kset.uevent_ops = &memory_uevent_ops;
 	ret = sysdev_class_register(&memory_sysdev_class);
 	if (ret)
 		goto out;
 
+	block_sz = get_memory_block_size();
+	sections_per_block = block_sz / MIN_MEMORY_BLOCK_SIZE;
+
 	/*
 	 * Create entries for memory sections that were found
 	 * during boot and have been initialized

@@ -569,8 +624,8 @@ int __init memory_dev_init(void)
 	for (i = 0; i < NR_MEM_SECTIONS; i++) {
 		if (!present_section_nr(i))
 			continue;
-		err = add_memory_block(0, __nr_to_section(i), MEM_ONLINE,
-				       BOOT);
+		err = add_memory_section(0, __nr_to_section(i), MEM_ONLINE,
+					 BOOT);
 		if (!ret)
 			ret = err;
 	}

Dave Hansen

2010-07-20 19:17 UTC #13 lore raw

Re: [PATCH 4/8] v3 Allow memory_block to span multiple memory sections

In reply to Nathan Fontenot

Quoted 9 lines · Nathan Fontenot

drivers/base/memory.c +9 -0

+static int add_memory_section(int nid, struct mem_section *section,
+                       unsigned long state, enum mem_add_context context)
+{
+       struct memory_block *mem;
+       int ret = 0;
+
+       mem = find_memory_block(section);
+       if (mem) {
+               atomic_inc(&mem->section_count);

drivers/base/memory.c static int add_memory_block(int nid, str · line 541

Quoted 10 lines

drivers/base/memory.c +6 -1

+               kobject_put(&mem->sysdev.kobj);
+       } else
+               ret = init_memory_block(&mem, section, state);
+
        if (!ret) {
-               if (context == HOTPLUG)
+               if (context == HOTPLUG &&
+                   atomic_read(&mem->section_count) == sections_per_block)
                        ret = register_mem_sect_under_node(mem, nid);
        }

I think the atomic_inc() can race with the atomic_dec_and_test() in remove_memory_block().

Thread 1 does:

	mem = find_memory_block(section);

Thread 2 does

	atomic_dec_and_test(&mem->section_count);

and destroys the memory block, Thread 1 runs again:

       if (mem) {
               atomic_inc(&mem->section_count);
               kobject_put(&mem->sysdev.kobj);
       } else

but now mem got destroyed by Thread 2. You probably need to change find_memory_block() to itself take a reference, and to use atomic_inc_unless().

-- Dave

Nathan Fontenot

author

2010-07-24 03:10 UTC #14 lore raw

Re: [PATCH 4/8] v3 Allow memory_block to span multiple memory sections

Quoted 34 lines · Dave Hansen

Quoted 9 lines · Nathan Fontenot

drivers/base/memory.c +9 -0

+static int add_memory_section(int nid, struct mem_section *section,
+                       unsigned long state, enum mem_add_context context)
+{
+       struct memory_block *mem;
+       int ret = 0;
+
+       mem = find_memory_block(section);
+       if (mem) {
+               atomic_inc(&mem->section_count);

drivers/base/memory.c static int add_memory_block(int nid, str · line 541

Quoted 10 lines

drivers/base/memory.c +6 -1

+               kobject_put(&mem->sysdev.kobj);
+       } else
+               ret = init_memory_block(&mem, section, state);
+
        if (!ret) {
-               if (context == HOTPLUG)
+               if (context == HOTPLUG &&
+                   atomic_read(&mem->section_count) == sections_per_block)
                        ret = register_mem_sect_under_node(mem, nid);
        }

I think the atomic_inc() can race with the atomic_dec_and_test() in remove_memory_block().

Thread 1 does:

	mem = find_memory_block(section);

Thread 2 does

	atomic_dec_and_test(&mem->section_count);

and destroys the memory block, Thread 1 runs again:

Quoted 9 lines

       if (mem) {
               atomic_inc(&mem->section_count);
               kobject_put(&mem->sysdev.kobj);
       } else
but now mem got destroyed by Thread 2. You probably need to change find_memory_block() to itself take a reference, and to use atomic_inc_unless().

You're right but I think the fix you suggested will narrow the window for the race condition, not eliminate it. We could still take a time splice in find_memory_block prior to the container_of() calls to get the memory block pointer and end up de-referencing a invalid kobject o sysdev pointer.

I think if we want to eliminate this we may need to have lock that protects access to any of the memory_block structures. This would need to be taken any time find_memory_block is called and released when use of the memory_block returned is finished. If we're going to fix this we should eliminate the window completely instead of just closing it further.

If we add a lock should I submit it as part of this patchset? or submit it as a follow-on?

-Nathan

Dave Hansen

2010-07-27 02:36 UTC #15 lore raw

Re: [PATCH 4/8] v3 Allow memory_block to span multiple memory sections

Quoted 3 lines · Nathan Fontenot

If we add a lock should I submit it as part of this patchset? or submit it
as a follow-on?

It should probably be at the beginning of the patch set. We don't want to have a case where your set introduces races that we _need_ a later patch to fix.

-- Dave

Nathan Fontenot

author

2010-07-26 19:10 UTC #16 lore raw

Re: [PATCH 4/8] v3 Allow memory_block to span multiple memory sections

In reply to Dave Hansen

Quoted 34 lines · Dave Hansen

Quoted 9 lines · Nathan Fontenot

drivers/base/memory.c +9 -0

+static int add_memory_section(int nid, struct mem_section *section,
+                       unsigned long state, enum mem_add_context context)
+{
+       struct memory_block *mem;
+       int ret = 0;
+
+       mem = find_memory_block(section);
+       if (mem) {
+               atomic_inc(&mem->section_count);

drivers/base/memory.c static int add_memory_block(int nid, str · line 541

Quoted 10 lines

drivers/base/memory.c +6 -1

+               kobject_put(&mem->sysdev.kobj);
+       } else
+               ret = init_memory_block(&mem, section, state);
+
        if (!ret) {
-               if (context == HOTPLUG)
+               if (context == HOTPLUG &&
+                   atomic_read(&mem->section_count) == sections_per_block)
                        ret = register_mem_sect_under_node(mem, nid);
        }

I think the atomic_inc() can race with the atomic_dec_and_test() in remove_memory_block().

Thread 1 does:

	mem = find_memory_block(section);

Thread 2 does

	atomic_dec_and_test(&mem->section_count);

and destroys the memory block, Thread 1 runs again:

Quoted 9 lines

       if (mem) {
               atomic_inc(&mem->section_count);
               kobject_put(&mem->sysdev.kobj);
       } else
but now mem got destroyed by Thread 2. You probably need to change find_memory_block() to itself take a reference, and to use atomic_inc_unless().

I'm not sure I like that for a couple of reasons. I think there may still be a path through the find_memory_block() code that this race condition can occur. We could take a time sslice after the kobject_get and before getting the memory_block pointer.

The second reason is that the node sysfs code calls find_memory_block() and it may be a bit kludgy to have callers of find_memory_block have to reduce the section_count after using it.

With the way the memory_block structs are kept, retrieved via a kobject_get() call instead maintained on a local list, there may not be a solution that is foolproof without changing this.

-Nathan

Quoted 2 lines

-- Dave

Dave Hansen

2010-07-20 19:21 UTC #17 lore raw

Re: [PATCH 4/8] v3 Allow memory_block to span multiple memory sections

In reply to Nathan Fontenot

drivers/base/memory.c int unregister_memory_section(struct mem · line 598

Quoted 9 lines · Nathan Fontenot

drivers/base/memory.c +9 -0

+static u32 get_memory_block_size(void)
+{
+       u32 block_sz;
+
+       block_sz = memory_block_size_bytes();
+
+       /* Validate blk_sz is a power of 2 and not less than section size */
+       if ((block_sz & (block_sz - 1)) || (block_sz < MIN_MEMORY_BLOCK_SIZE))
+               block_sz = MIN_MEMORY_BLOCK_SIZE;

Is this worth a WARN_ON()? Seems pretty bogus if someone is returning funky block sizes.

-- Dave

Nathan Fontenot

author

2010-07-20 03:56 UTC #18 lore raw

PATCH 5/8 v3 Update the find_memory_block declaration

In reply to Nathan Fontenot

Update the find_memory_block declaration to to take a struct mem_section * so that it matches the definition.

Signed-off-by Nathan Fontenot <[email protected]>

---
 include/linux/memory.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

include/linux/memory.h +1 -1

Index: linux-2.6/include/linux/memory.h
===================================================================
@@ -116,7 +116,7 @@ extern int memory_dev_init(void);
 extern int remove_memory_block(unsigned long, struct mem_section *, int);
 extern int memory_notify(unsigned long val, void *v);
 extern int memory_isolate_notify(unsigned long val, void *v);
-extern struct memory_block *find_memory_block(unsigned long);
+extern struct memory_block *find_memory_block(struct mem_section *);
 extern int memory_is_hidden(struct mem_section *);
 #define CONFIG_MEM_BLOCK_SIZE	(PAGES_PER_SECTION<<PAGE_SHIFT)
 enum mem_add_context { BOOT, HOTPLUG };

KAMEZAWA Hiroyuki

2010-07-20 07:21 UTC #19 lore raw

Re: [PATCH 5/8] v3 Update the find_memory_block declaration

Quoted 4 lines · On Mon, 19 Jul 2010 22:56:16 -0500 Nathan Fontenot <[email protected]> wrote:

Update the find_memory_block declaration to to take a struct mem_section * so that it matches the definition.
Signed-off-by Nathan Fontenot <[email protected]>

Reviewd-by KAMEZAWA Hiroyuki <[email protected]>

Nathan Fontenot

author

2010-07-20 03:57 UTC #20 lore raw

PATCH 6/8 v3 Update the node sysfs code

In reply to Nathan Fontenot

Update the node sysfs code to be aware of the new capability for a memory block to contain multiple memory sections. This requires an additional parameter to unregister_mem_sect_under_nodes so that we know which memory section of the memory block to unregister.

Signed-off-by Nathan Fontenot <[email protected]>

---
 drivers/base/memory.c |    2 +-
 drivers/base/node.c   |   12 ++++++++----
 include/linux/node.h  |    3 ++-
 3 files changed, 11 insertions(+), 6 deletions(-)

drivers/base/node.c +8 -4

Index: linux-2.6/drivers/base/node.c
===================================================================
@@ -346,8 +346,10 @@ int register_mem_sect_under_node(struct
 		return -EFAULT;
 	if (!node_online(nid))
 		return 0;
-	sect_start_pfn = section_nr_to_pfn(mem_blk->phys_index);
-	sect_end_pfn = sect_start_pfn + PAGES_PER_SECTION - 1;
+
+	sect_start_pfn = section_nr_to_pfn(mem_blk->start_phys_index);
+	sect_end_pfn = section_nr_to_pfn(mem_blk->end_phys_index);
+	sect_end_pfn += PAGES_PER_SECTION - 1;
 	for (pfn = sect_start_pfn; pfn <= sect_end_pfn; pfn++) {
 		int page_nid;

@@ -371,7 +373,8 @@ int register_mem_sect_under_node(struct
 }
 
 /* unregister memory section under all nodes that it spans */
-int unregister_mem_sect_under_nodes(struct memory_block *mem_blk)
+int unregister_mem_sect_under_nodes(struct memory_block *mem_blk,
+				    unsigned long phys_index)
 {
 	NODEMASK_ALLOC(nodemask_t, unlinked_nodes, GFP_KERNEL);
 	unsigned long pfn, sect_start_pfn, sect_end_pfn;

@@ -383,7 +386,8 @@ int unregister_mem_sect_under_nodes(stru
 	if (!unlinked_nodes)
 		return -ENOMEM;
 	nodes_clear(*unlinked_nodes);
-	sect_start_pfn = section_nr_to_pfn(mem_blk->phys_index);
+
+	sect_start_pfn = section_nr_to_pfn(phys_index);
 	sect_end_pfn = sect_start_pfn + PAGES_PER_SECTION - 1;
 	for (pfn = sect_start_pfn; pfn <= sect_end_pfn; pfn++) {
 		int nid;

drivers/base/memory.c +1 -1

Index: linux-2.6/drivers/base/memory.c
===================================================================
@@ -550,9 +550,9 @@ int remove_memory_block(unsigned long no
 
 	mem = find_memory_block(section);
 	atomic_dec(&mem->section_count);
+	unregister_mem_sect_under_nodes(mem, __section_nr(section));
 
 	if (atomic_read(&mem->section_count) == 0) {
-		unregister_mem_sect_under_nodes(mem);
 		mem_remove_simple_file(mem, start_phys_index);
 		mem_remove_simple_file(mem, end_phys_index);
 		mem_remove_simple_file(mem, state);

include/linux/node.h +2 -1

Index: linux-2.6/include/linux/node.h
===================================================================
@@ -44,7 +44,8 @@ extern int register_cpu_under_node(unsig
 extern int unregister_cpu_under_node(unsigned int cpu, unsigned int nid);
 extern int register_mem_sect_under_node(struct memory_block *mem_blk,
 						int nid);
-extern int unregister_mem_sect_under_nodes(struct memory_block *mem_blk);
+extern int unregister_mem_sect_under_nodes(struct memory_block *mem_blk,
+					   unsigned long phys_index);
 
 #ifdef CONFIG_HUGETLBFS
 extern void register_hugetlbfs_with_node(node_registration_func_t doregister,

KAMEZAWA Hiroyuki

Acked-by on v1 6/8

2010-07-20 07:22 UTC #21 lore raw

Re: [PATCH 6/8] v3 Update the node sysfs code

Quoted 6 lines · On Mon, 19 Jul 2010 22:57:35 -0500 Nathan Fontenot <[email protected]> wrote:

Update the node sysfs code to be aware of the new capability for a memory block to contain multiple memory sections. This requires an additional parameter to unregister_mem_sect_under_nodes so that we know which memory section of the memory block to unregister.
Signed-off-by Nathan Fontenot <[email protected]>

Acked-by KAMEZAWA Hiroyuki <[email protected]>

Brian King

2010-07-28 13:50 UTC #22 lore raw

Re: [PATCH 6/8] v3 Update the node sysfs code

In reply to Nathan Fontenot

include/linux/node.h extern int register_cpu_under_node(unsig · line 48

Quoted 11 lines · Nathan Fontenot

Index: linux-2.6/include/linux/node.h
===================================================================

include/linux/node.h +2 -1

@@ -44,7 +44,8 @@ extern int register_cpu_under_node(unsig
 extern int unregister_cpu_under_node(unsigned int cpu, unsigned int nid);
 extern int register_mem_sect_under_node(struct memory_block *mem_blk,
 						int nid);
-extern int unregister_mem_sect_under_nodes(struct memory_block *mem_blk);
+extern int unregister_mem_sect_under_nodes(struct memory_block *mem_blk,
+					   unsigned long phys_index);

You also need to update the inline definition of unregister_mem_sect_under_nodes for the !CONFIG_NUMA case.

-Brian

Signature · 3 lines

Brian King
Linux on Power Virtualization
IBM Linux Technology Center

Nathan Fontenot

author

2010-07-20 03:59 UTC #23 lore raw

PATCH 7/8 v3 Define memory_block_size_bytes() for ppc/pseries

In reply to Nathan Fontenot

Define a version of memory_block_size_bytes() for powerpc/pseries such that a memory block spans an entire lmb.

Signed-off-by Nathan Fontenot <[email protected]>

---
 arch/powerpc/platforms/pseries/hotplug-memory.c |   66 +++++++++++++++++++-----
 1 file changed, 53 insertions(+), 13 deletions(-)

arch/powerpc/platforms/pseries/hotplug-memory.c +53 ~~-13~~

Index: linux-2.6/arch/powerpc/platforms/pseries/hotplug-memory.c
===================================================================
@@ -17,6 +17,54 @@
 #include <asm/pSeries_reconfig.h>
 #include <asm/sparsemem.h>
 
+static u32 get_memblock_size(void)
+{
+	struct device_node *np;
+	unsigned int memblock_size = 0;
+
+	np = of_find_node_by_path("/ibm,dynamic-reconfiguration-memory");
+	if (np) {
+		const unsigned int *size;
+
+		size = of_get_property(np, "ibm,lmb-size", NULL);
+		memblock_size = size ? *size : 0;
+
+		of_node_put(np);
+	} else {
+		unsigned int memzero_size = 0;
+		const unsigned int *regs;
+
+		np = of_find_node_by_path("/memory@0");
+		if (np) {
+			regs = of_get_property(np, "reg", NULL);
+			memzero_size = regs ? regs[3] : 0;
+			of_node_put(np);
+		}
+
+		if (memzero_size) {
+			/* We now know the size of memory@0, use this to find
+			 * the first memoryblock and get its size.
+			 */
+			char buf[64];
+
+			sprintf(buf, "/memory@%x", memzero_size);
+			np = of_find_node_by_path(buf);
+			if (np) {
+				regs = of_get_property(np, "reg", NULL);
+				memblock_size = regs ? regs[3] : 0;
+				of_node_put(np);
+			}
+		}
+	}
+
+	return memblock_size;
+}
+
+u32 memory_block_size_bytes(void)
+{
+	return get_memblock_size();
+}
+
 static int pseries_remove_memblock(unsigned long base, unsigned int memblock_size)
 {
 	unsigned long start, start_pfn;

@@ -127,30 +175,22 @@ static int pseries_add_memory(struct dev
 
 static int pseries_drconf_memory(unsigned long *base, unsigned int action)
 {
-	struct device_node *np;
-	const unsigned long *memblock_size;
+	unsigned long memblock_size;
 	int rc;
 
-	np = of_find_node_by_path("/ibm,dynamic-reconfiguration-memory");
-	if (!np)
+	memblock_size = get_memblock_size();
+	if (!memblock_size)
 		return -EINVAL;
 
-	memblock_size = of_get_property(np, "ibm,memblock-size", NULL);
-	if (!memblock_size) {
-		of_node_put(np);
-		return -EINVAL;
-	}
-
 	if (action == PSERIES_DRCONF_MEM_ADD) {
-		rc = memblock_add(*base, *memblock_size);
+		rc = memblock_add(*base, memblock_size);
 		rc = (rc < 0) ? -EINVAL : 0;
 	} else if (action == PSERIES_DRCONF_MEM_REMOVE) {
-		rc = pseries_remove_memblock(*base, *memblock_size);
+		rc = pseries_remove_memblock(*base, memblock_size);
 	} else {
 		rc = -EINVAL;
 	}
 
-	of_node_put(np);
 	return rc;
 }

Brian King

2010-07-21 20:27 UTC #24 lore raw

Re: [PATCH 7/8] v3 Define memory_block_size_bytes() for ppc/pseries

arch/powerpc/platforms/pseries/hotplug-memory.c line 27

Quoted 9 lines · Nathan Fontenot

arch/powerpc/platforms/pseries/hotplug-memory.c +8 -0

+static u32 get_memblock_size(void)
+{
+	struct device_node *np;
+	unsigned int memblock_size = 0;
+
+	np = of_find_node_by_path("/ibm,dynamic-reconfiguration-memory");
+	if (np) {
+		const unsigned int *size;

This needs to be an unsigned long, otherwise I always get zero on my p6.

Quoted 5 lines

arch/powerpc/platforms/pseries/hotplug-memory.c +5 -0

+
+		size = of_get_property(np, "ibm,lmb-size", NULL);
+		memblock_size = size ? *size : 0;
+
+		of_node_put(np);

Signature · 3 lines

Brian King
Linux on Power Virtualization
IBM Linux Technology Center

Nathan Fontenot

author

2010-07-20 04:00 UTC #25 lore raw

PATCH 8/8 v3 Update memory-hotplug documentation

In reply to Nathan Fontenot

Update the memory hotplug documentation to reflect the new behaviors of memory blocks reflected in sysfs.

Signed-off-by Nathan Fontent <[email protected]>

---
 Documentation/memory-hotplug.txt |   40 +++++++++++++++++++++++----------------
 1 file changed, 24 insertions(+), 16 deletions(-)

Documentation/memory-hotplug.txt +24 ~~-16~~

Index: linux-2.6/Documentation/memory-hotplug.txt
===================================================================
@@ -126,36 +126,44 @@ config options.
 --------------------------------
 4 sysfs files for memory hotplug
 --------------------------------
-All sections have their device information under /sys/devices/system/memory as
+All sections have their device information in sysfs.  Each section is part of
+a memory block under /sys/devices/system/memory as
 
 /sys/devices/system/memory/memoryXXX
-(XXX is section id.)
+(XXX is the section id.)
 
-Now, XXX is defined as start_address_of_section / section_size.
+Now, XXX is defined as (start_address_of_section / section_size) of the first
+section conatined in the memory block.
 
 For example, assume 1GiB section size. A device for a memory starting at
 0x100000000 is /sys/device/system/memory/memory4
 (0x100000000 / 1Gib = 4)
 This device covers address range [0x100000000 ... 0x140000000)
 
-Under each section, you can see 4 files.
+Under each section, you can see 5 files.
 
-/sys/devices/system/memory/memoryXXX/phys_index
+/sys/devices/system/memory/memoryXXX/start_phys_index
+/sys/devices/system/memory/memoryXXX/end_phys_index
 /sys/devices/system/memory/memoryXXX/phys_device
 /sys/devices/system/memory/memoryXXX/state
 /sys/devices/system/memory/memoryXXX/removable
 
-'phys_index' : read-only and contains section id, same as XXX.
-'state'      : read-write
-               at read:  contains online/offline state of memory.
-               at write: user can specify "online", "offline" command
-'phys_device': read-only: designed to show the name of physical memory device.
-               This is not well implemented now.
-'removable'  : read-only: contains an integer value indicating
-               whether the memory section is removable or not
-               removable.  A value of 1 indicates that the memory
-               section is removable and a value of 0 indicates that
-               it is not removable.
+'start_phys_index' : read-only and contains section id of the first section
+		     in the memory block, same as XXX.
+'end_phys_index'   : read-only and contains section id of the last section
+		     in the memory block.
+'state'            : read-write
+                     at read:  contains online/offline state of memory.
+                     at write: user can specify "online", "offline" command
+                     which will be performed on al sections in the block.
+'phys_device'      : read-only: designed to show the name of physical memory
+                     device.  This is not well implemented now.
+'removable'        : read-only: contains an integer value indicating
+                     whether the memory block is removable or not
+                     removable.  A value of 1 indicates that the memory
+                     block is removable and a value of 0 indicates that
+                     it is not removable. A memory block is removable only if
+                     every section in the block is removable.
 
 NOTE:
   These directories/files appear after physical memory hotplug phase.

Dave Hansen

2010-07-20 19:23 UTC #26 lore raw

Re: [PATCH 8/8] v3 Update memory-hotplug documentation

Quoted 13 lines · Nathan Fontenot

(quoted diff) +1 -1
-Now, XXX is defined as start_address_of_section / section_size.
+Now, XXX is defined as (start_address_of_section / section_size) of
the first
+section conatined in the memory block.
For example, assume 1GiB section size. A device for a memory starting
at
0x100000000 is /sys/device/system/memory/memory4 (0x100000000 / 1Gib = 4)
This device covers address range [0x100000000 ... 0x140000000)

Documentation/memory-hotplug.txt config options. · line 146

Quoted 6 lines

Documentation/memory-hotplug.txt +3 -2

-Under each section, you can see 4 files.
+Under each section, you can see 5 files.
 
-/sys/devices/system/memory/memoryXXX/phys_index
+/sys/devices/system/memory/memoryXXX/start_phys_index
+/sys/devices/system/memory/memoryXXX/end_phys_index

Just wanted to make sure you didn't forget to update this after KAME's comments on the first couple of patches.

-- Dave

Benjamin Herrenschmidt

2010-07-31 05:38 UTC #27 lore raw

In reply to Nathan Fontenot

Quoted 8 lines · Nathan Fontenot

This set of patches de-couples the idea that there is a single directory in sysfs for each memory section. The intent of the patches is to reduce the number of sysfs directories created to resolve a boot-time performance issue. On very large systems boot time are getting very long (as seen on powerpc hardware) due to the enormous number of sysfs directories being created. On a system with 1 TB of memory we create ~63,000 directories. For even larger systems boot times are being measured in hours.

Greg, Kame, how do we proceed with these ? I'm happy to put them in powerpc.git with appropriate acks or will you take them ?

Cheers,
Ben.

Greg KH

2010-07-31 19:58 UTC #28 lore raw

Quoted 10 lines · Benjamin Herrenschmidt

Quoted 8 lines · Nathan Fontenot
This set of patches de-couples the idea that there is a single directory in sysfs for each memory section. The intent of the patches is to reduce the number of sysfs directories created to resolve a boot-time performance issue. On very large systems boot time are getting very long (as seen on powerpc hardware) due to the enormous number of sysfs directories being created. On a system with 1 TB of memory we create ~63,000 directories. For even larger systems boot times are being measured in hours.

Quoted 2 lines

Greg, Kame, how do we proceed with these ? I'm happy to put them in powerpc.git with appropriate acks or will you take them ?

I thought there would be at least one more round of these patches based on the review comments, right?

I'll be glad to take them when everyone agrees with them.

thanks,

greg k-h

Benjamin Herrenschmidt

2010-08-01 00:29 UTC #29 lore raw

Quoted 11 lines · Greg KH

Quoted 10 lines · Benjamin Herrenschmidt
Quoted 8 lines · Nathan Fontenot
This set of patches de-couples the idea that there is a single directory in sysfs for each memory section. The intent of the patches is to reduce the number of sysfs directories created to resolve a boot-time performance issue. On very large systems boot time are getting very long (as seen on powerpc hardware) due to the enormous number of sysfs directories being created. On a system with 1 TB of memory we create ~63,000 directories. For even larger systems boot times are being measured in hours.

Quoted 5 lines

Quoted 2 lines
Greg, Kame, how do we proceed with these ? I'm happy to put them in powerpc.git with appropriate acks or will you take them ?
I thought there would be at least one more round of these patches based on the review comments, right?

Yes, but I was nontheless inquiring whether I should pick them up after said repost :-)

Quoted 1 line

I'll be glad to take them when everyone agrees with them.

Ok, good, one less thing to worry about in powerpc patchwork :-)

Cheers,
Ben.

Quoted 3 lines

thanks,
greg k-h