mm: process/cgroup ksm support
Subsystems (6)
v2 cover mm: process/cgroup ksm support
So far KSM can only be enabled by calling madvise for memory regions. What is required to enable KSM for more workloads is to enable / disable it at the process / cgroup level.
Use case:
The madvise call is not available in the programming language. An example for this are programs with forked workloads using a garbage collected language without pointers. In such a language madvise cannot be made available.
In addition the addresses of objects get moved around as they are garbage collected. KSM sharing needs to be enabled "from the outside" for these type of workloads.
Experiments with using UKSM have shown a capacity increase of around 20%.
1. New options for prctl system command
This patch series adds two new options to the prctl system call. The first one allows to enable KSM at the process level and the second one to query the setting.
The setting will be inherited by child processes.
With the above setting, KSM can be enabled for the seed process of a cgroup and all processes in the cgroup will inherit the setting.
2. Changes to KSM processing
When KSM is enabled at the process level, the KSM code will iterate over all the VMA's and enable KSM for the eligible VMA's.
When forking a process that has KSM enabled, the setting will be inherited by the new child process.
In addition when KSM is disabled for a process, KSM will be disabled for the VMA's where KSM has been enabled.
3. Add general_profit metric
The general_profit metric of KSM is specified in the documentation, but not calculated. This adds the general profit metric to /sys/kernel/debug/mm/ksm.
4. Add more metrics to ksm_stat
This adds the process profit and ksm type metric to /proc/<pid>/ksm_stat.
5. Add more tests to ksm_tests
This adds an option to specify the merge type to the ksm_tests. This allows to test madvise and prctl KSM. It also adds a new option to query if prctl KSM has been enabled. It adds a fork test to verify that the KSM process setting is inherited by client processes.
Changes:
- V2:
- Added use cases to the cover letter
- Removed the tracing patch from the patch series and posted it as an individual patch
- Refreshed repo
Stefan Roesch (19):
mm: add new flag to enable ksm per process
mm: add flag to __ksm_enter
mm: add flag to __ksm_exit call
mm: invoke madvise for all vmas in scan_get_next_rmap_item
mm: support disabling of ksm for a process
mm: add new prctl option to get and set ksm for a process
mm: split off pages_volatile function
mm: expose general_profit metric
docs: document general_profit sysfs knob
mm: calculate ksm process profit metric
mm: add ksm_merge_type() function
mm: expose ksm process profit metric in ksm_stat
mm: expose ksm merge type in ksm_stat
docs: document new procfs ksm knobs
tools: add new prctl flags to prctl in tools dir selftests/vm: add KSM prctl merge test selftests/vm: add KSM get merge type test selftests/vm: add KSM fork test
selftests/vm: add two functions for debugging merge outcome
Documentation/ABI/testing/sysfs-kernel-mm-ksm | 8 + Documentation/admin-guide/mm/ksm.rst | 8 +- fs/proc/base.c | 5 + include/linux/ksm.h | 19 +- include/linux/sched/coredump.h | 1 + include/uapi/linux/prctl.h | 2 + kernel/sys.c | 29 ++ mm/ksm.c | 114 +++++++- tools/include/uapi/linux/prctl.h | 2 + tools/testing/selftests/mm/Makefile | 3 +- tools/testing/selftests/mm/ksm_tests.c | 254 +++++++++++++++--- 11 files changed, 389 insertions(+), 56 deletions(-)
base-commit: 234a68e24b120b98875a8b6e17a9dead277be16a
Signature · 1 line
2.30.2
RFC PATCH v2 1/19 mm: add new flag to enable ksm per process
This introduces the new flag MMF_VM_MERGE_ANY flag. When this flag is set, kernel samepage merging (ksm) gets enabled for all vma's of a process.
--- include/linux/sched/coredump.h | 1 + 1 file changed, 1 insertion(+)
include/linux/sched/coredump.h +1 -0
@@ -90,4 +90,5 @@ static inline int get_dumpable(struct mm_struct *mm)#define MMF_INIT_MASK (MMF_DUMPABLE_MASK | MMF_DUMP_FILTER_MASK |\ MMF_DISABLE_THP_MASK | MMF_HAS_MDWE_MASK) +#define MMF_VM_MERGE_ANY 29#endif /* _LINUX_SCHED_COREDUMP_H */
Signature · 1 line
2.30.2
RFC PATCH v2 2/19 mm: add flag to __ksm_enter
In reply to Stefan RoeschThis change adds the flag parameter to __ksm_enter. This allows to distinguish if ksm was called by prctl or madvise.
--- include/linux/ksm.h | 6 ++++-- mm/ksm.c | 9 +++++---- 2 files changed, 9 insertions(+), 6 deletions(-)
include/linux/ksm.h +4 -2
@@ -18,13 +18,15 @@#ifdef CONFIG_KSM int ksm_madvise (struct vm_area_struct *vma,unsigned long start,unsigned long end,int advice,unsigned long *vm_flags); -int __ksm_enter (struct mm_struct *mm);void __ksm_exit (struct mm_struct *mm); +int __ksm_enter (struct mm_struct *mm,int flag);static inline int ksm_fork (struct mm_struct *mm,struct mm_struct *oldmm) { +if (test_bit (MMF_VM_MERGE_ANY , &oldmm->flags)) +return __ksm_enter (mm,MMF_VM_MERGE_ANY );if (test_bit (MMF_VM_MERGEABLE , &oldmm->flags)) -return __ksm_enter (mm); +return __ksm_enter (mm,MMF_VM_MERGEABLE );return 0 ; }
mm/ksm.c +5 -4
@@ -2595,8 +2595,9 @@ int ksm_madvise(struct vm_area_struct *vma, unsigned long start,return 0 ;#endif -if (!test_bit (MMF_VM_MERGEABLE , &mm->flags)) { - err =__ksm_enter (mm); +if (!test_bit (MMF_VM_MERGEABLE , &mm->flags) && + !test_bit (MMF_VM_MERGE_ANY , &mm->flags)) { + err =__ksm_enter (mm,MMF_VM_MERGEABLE );if (err)return err; }
@@ -2622,7 +2623,7 @@ int ksm_madvise(struct vm_area_struct *vma, unsigned long start, }EXPORT_SYMBOL_GPL (ksm_madvise); -int __ksm_enter (struct mm_struct *mm) +int __ksm_enter (struct mm_struct *mm,int flag) {struct ksm_mm_slot *mm_slot;struct mm_slot *slot;
@@ -2655,7 +2656,7 @@ int __ksm_enter(struct mm_struct *mm)list_add_tail (&slot->mm_node, &ksm_scan.mm_slot->slot.mm_node);spin_unlock (&ksm_mmlist_lock); -set_bit (MMF_VM_MERGEABLE , &mm->flags); +set_bit (flag, &mm->flags);mmgrab (mm);if (needs_wakeup)
Signature · 1 line
2.30.2
RFC PATCH v2 3/19 mm: add flag to __ksm_exit call
In reply to Stefan RoeschThis adds the flag parameter to the __ksm_exit() call. This allows to distinguish if this call is for an prctl or madvise invocation.
--- include/linux/ksm.h | 8 +++++--- mm/ksm.c | 8 ++++++-- 2 files changed, 11 insertions(+), 5 deletions(-)
include/linux/ksm.h +5 -3
@@ -18,8 +18,8 @@#ifdef CONFIG_KSM int ksm_madvise (struct vm_area_struct *vma,unsigned long start,unsigned long end,int advice,unsigned long *vm_flags); -void __ksm_exit (struct mm_struct *mm);int __ksm_enter (struct mm_struct *mm,int flag); +void __ksm_exit (struct mm_struct *mm,int flag);static inline int ksm_fork (struct mm_struct *mm,struct mm_struct *oldmm) {
@@ -32,8 +32,10 @@ static inline int ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm)static inline void ksm_exit (struct mm_struct *mm) { -if (test_bit (MMF_VM_MERGEABLE , &mm->flags)) -__ksm_exit (mm); +if (test_bit (MMF_VM_MERGE_ANY , &mm->flags)) +__ksm_exit (mm,MMF_VM_MERGE_ANY ); +else if (test_bit (MMF_VM_MERGEABLE , &mm->flags)) +__ksm_exit (mm,MMF_VM_MERGEABLE ); }/*
mm/ksm.c +6 -2
@@ -2665,12 +2665,16 @@ int __ksm_enter(struct mm_struct *mm, int flag)return 0 ; } -void __ksm_exit (struct mm_struct *mm) +void __ksm_exit (struct mm_struct *mm,int flag) {struct ksm_mm_slot *mm_slot;struct mm_slot *slot;int easy_to_free =0 ; +if (!(current->flags &PF_EXITING ) && flag ==MMF_VM_MERGE_ANY && +test_bit (MMF_VM_MERGE_ANY , &mm->flags)) +clear_bit (MMF_VM_MERGE_ANY , &mm->flags); +/* * This process is exiting: if it's straightforward (as is the * case when ksmd was never running), free mm_slot immediately.
@@ -2697,7 +2701,7 @@ void __ksm_exit(struct mm_struct *mm)if (easy_to_free) {mm_slot_free (mm_slot_cache, mm_slot); -clear_bit (MMF_VM_MERGEABLE , &mm->flags); +clear_bit (flag, &mm->flags);mmdrop (mm); }else if (mm_slot) {mmap_write_lock (mm);
Signature · 1 line
2.30.2
RFC PATCH v2 4/19 mm: invoke madvise for all vmas in scan_get_next_rmap_item
In reply to Stefan RoeschIf the new flag MMF_VM_MERGE_ANY has been set for a process, iterate over all the vmas and enable ksm if possible. For the vmas that can be ksm enabled this is only done once.
--- mm/ksm.c | 27 ++++++++++++++++++++++++++- 1 file changed, 26 insertions(+), 1 deletion(-)
mm/ksm.c +26 -1
@@ -1063,6 +1063,7 @@ static int unmerge_and_remove_all_rmap_items(void)mm_slot_free (mm_slot_cache, mm_slot);clear_bit (MMF_VM_MERGEABLE , &mm->flags); +clear_bit (MMF_VM_MERGE_ANY , &mm->flags);mmdrop (mm); }else spin_unlock (&ksm_mmlist_lock);
@@ -2329,6 +2330,17 @@ static struct ksm_rmap_item *get_next_rmap_item(struct ksm_mm_slot *mm_slot,return rmap_item; } +static bool vma_ksm_mergeable (struct vm_area_struct *vma) +{ +if (vma->vm_flags &VM_MERGEABLE ) +return true; + +if (test_bit (MMF_VM_MERGE_ANY , &vma->vm_mm->flags)) +return true; + +return false; +} +static struct ksm_rmap_item *scan_get_next_rmap_item (struct page **page) {struct mm_struct *mm;
@@ -2405,8 +2417,20 @@ static struct ksm_rmap_item *scan_get_next_rmap_item(struct page **page) goto no_vmas;for_each_vma (vmi, vma) { -if (!(vma->vm_flags &VM_MERGEABLE )) +if (!vma_ksm_mergeable (vma))continue ; +if (!(vma->vm_flags &VM_MERGEABLE )) { +unsigned long flags = vma->vm_flags; + +/* madvise failed, use next vma */ +if (ksm_madvise (vma, vma->vm_start, vma->vm_end,MADV_MERGEABLE , &flags)) +continue ; +/* vma, not supported as being mergeable */ +if (!(flags &VM_MERGEABLE )) +continue ; + +vm_flags_set (vma,VM_MERGEABLE ); + }if (ksm_scan.address < vma->vm_start) ksm_scan.address = vma->vm_start;if (!vma->anon_vma)
@@ -2491,6 +2515,7 @@ static struct ksm_rmap_item *scan_get_next_rmap_item(struct page **page)mm_slot_free (mm_slot_cache, mm_slot);clear_bit (MMF_VM_MERGEABLE , &mm->flags); +clear_bit (MMF_VM_MERGE_ANY , &mm->flags);mmap_read_unlock (mm);mmdrop (mm); }else {
Signature · 1 line
2.30.2
RFC PATCH v2 5/19 mm: support disabling of ksm for a process
In reply to Stefan RoeschThis adds the ability to disable ksm for a process if ksm has been enabled for the process.
--- mm/ksm.c | 25 ++++++++++++++++++++++++- 1 file changed, 24 insertions(+), 1 deletion(-)
mm/ksm.c +24 -1
@@ -2690,6 +2690,27 @@ int __ksm_enter(struct mm_struct *mm, int flag)return 0 ; } +static void unmerge_vmas (struct mm_struct *mm) +{ +struct vm_area_struct *vma; +struct vma_iterator vmi; + +vma_iter_init (&vmi, mm,0 ); + +mmap_read_lock (mm); +for_each_vma (vmi, vma) { +if (vma->vm_flags &VM_MERGEABLE ) { +unsigned long flags = vma->vm_flags; + +if (ksm_madvise (vma, vma->vm_start, vma->vm_end,MADV_UNMERGEABLE , &flags)) +continue ; + +vm_flags_clear (vma,VM_MERGEABLE ); + } + } +mmap_read_unlock (mm); +} +void __ksm_exit (struct mm_struct *mm,int flag) {struct ksm_mm_slot *mm_slot;
@@ -2697,8 +2718,10 @@ void __ksm_exit(struct mm_struct *mm, int flag)int easy_to_free =0 ;if (!(current->flags &PF_EXITING ) && flag ==MMF_VM_MERGE_ANY && -test_bit (MMF_VM_MERGE_ANY , &mm->flags)) +test_bit (MMF_VM_MERGE_ANY , &mm->flags)) {clear_bit (MMF_VM_MERGE_ANY , &mm->flags); +unmerge_vmas (mm); + }/* * This process is exiting: if it's straightforward (as is the
Signature · 1 line
2.30.2
RFC PATCH v2 6/19 mm: add new prctl option to get and set ksm for a process
In reply to Stefan RoeschThis adds two new options to the prctl system call
- enable ksm for all vmas of a process (if the vmas support it).
- query if ksm has been enabled for a process.
--- include/uapi/linux/prctl.h | 2 ++ kernel/sys.c | 29 +++++++++++++++++++++++++++++ 2 files changed, 31 insertions(+)
include/uapi/linux/prctl.h +2 -0
@@ -290,4 +290,6 @@ struct prctl_mm_map {#define PR_SET_VMA 0x53564d41# define PR_SET_VMA_ANON_NAME 0 +#define PR_SET_MEMORY_MERGE 67 +#define PR_GET_MEMORY_MERGE 68#endif /* _LINUX_PRCTL_H */
kernel/sys.c +29 -0
@@ -15,6 +15,7 @@#include <linux/highuid.h> #include <linux/fs.h> #include <linux/kmod.h> +#include <linux/ksm.h> #include <linux/perf_event.h> #include <linux/resource.h> #include <linux/kernel.h>
@@ -2659,6 +2660,34 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,case PR_SET_VMA : error =prctl_set_vma (arg2, arg3, arg4, arg5);break ; +#ifdef CONFIG_KSM +case PR_SET_MEMORY_MERGE : +if (!capable (CAP_SYS_RESOURCE )) +return -EPERM ; + +if (arg2) { +if (mmap_write_lock_killable (me->mm)) +return -EINTR ; + +if (test_bit (MMF_VM_MERGEABLE , &me->mm->flags)) + error = -EINVAL ; +else if (!test_bit (MMF_VM_MERGE_ANY , &me->mm->flags)) + error =__ksm_enter (me->mm,MMF_VM_MERGE_ANY ); +mmap_write_unlock (me->mm); + }else { +__ksm_exit (me->mm,MMF_VM_MERGE_ANY ); + } +break ; +case PR_GET_MEMORY_MERGE : +if (!capable (CAP_SYS_RESOURCE )) +return -EPERM ; + +if (arg2 || arg3 || arg4 || arg5) +return -EINVAL ; + + error = !!test_bit (MMF_VM_MERGE_ANY , &me->mm->flags); +break ; +#endif default : error = -EINVAL ;break ;
Signature · 1 line
2.30.2
RFC PATCH v2 7/19 mm: split off pages_volatile function
In reply to Stefan RoeschThis splits off the pages_volatile function. The next patch will use this function.
--- mm/ksm.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-)
mm/ksm.c +9 -3
@@ -3271,8 +3271,7 @@ static ssize_t pages_unshared_show(struct kobject *kobj, }KSM_ATTR_RO (pages_unshared); -static ssize_t pages_volatile_show (struct kobject *kobj, -struct kobj_attribute *attr,char *buf) +static long pages_volatile (void ) {long ksm_pages_volatile;
@@ -3284,7 +3283,14 @@ static ssize_t pages_volatile_show(struct kobject *kobj,*/ if (ksm_pages_volatile <0 ) ksm_pages_volatile =0 ; -return sysfs_emit (buf,"%ld\n" , ksm_pages_volatile); + +return ksm_pages_volatile; +} + +static ssize_t pages_volatile_show (struct kobject *kobj, +struct kobj_attribute *attr,char *buf) +{ +return sysfs_emit (buf,"%ld\n" ,pages_volatile ()); }KSM_ATTR_RO (pages_volatile);
Signature · 1 line
2.30.2
RFC PATCH v2 8/19 mm: expose general_profit metric
In reply to Stefan RoeschThe documentation mentions a general profit metric, however this metric is not calculated. In addition the formula depends on the size of internal structures, which makes it more difficult for an administrator to make the calculation. Adding the metric for a better user experience.
--- mm/ksm.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+)
mm/ksm.c +16 -0
@@ -3301,6 +3301,21 @@ static ssize_t zero_pages_sharing_show(struct kobject *kobj, }KSM_ATTR_RO (zero_pages_sharing); +static ssize_t general_profit_show (struct kobject *kobj, +struct kobj_attribute *attr,char *buf) +{ +long general_profit; +long all_rmap_items; + + all_rmap_items = ksm_max_page_sharing + ksm_pages_shared + + ksm_pages_unshared +pages_volatile (); + general_profit = ksm_pages_sharing *PAGE_SIZE - + all_rmap_items *sizeof (struct ksm_rmap_item ); + +return sysfs_emit (buf,"%ld\n" , general_profit); +} +KSM_ATTR_RO (general_profit); +static ssize_t stable_node_dups_show (struct kobject *kobj,struct kobj_attribute *attr,char *buf) {
@@ -3366,6 +3381,7 @@ static struct attribute *ksm_attrs[] = { &stable_node_dups_attr.attr, &stable_node_chains_prune_millisecs_attr.attr, &use_zero_pages_attr.attr, + &general_profit_attr.attr, NULL, };
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2.30.2
RFC PATCH v2 9/19 docs: document general_profit sysfs knob
In reply to Stefan RoeschDocument general_progit knob.
--- Documentation/ABI/testing/sysfs-kernel-mm-ksm | 8 ++++++++ Documentation/admin-guide/mm/ksm.rst | 2 ++ 2 files changed, 10 insertions(+)
Documentation/ABI/testing/sysfs-kernel-mm-ksm +8 -0
@@ -51,3 +51,11 @@ Description: Control merging pages across different NUMA nodes. When it is set to 0 only pages from the same node are merged, otherwise pages from all nodes can be merged together (default). + +What: /sys/kernel/mm/ksm/general_profit +Date: January 2023 +KernelVersion: 6.1 +Contact: Linux memory management mailing list <[email protected]> +Description: Measure how effective KSM is. + general_profit: how effective is KSM. The formula for the + calculation is in Documentation/admin-guide/mm/ksm.rst.
Documentation/admin-guide/mm/ksm.rst +2 -0
@@ -159,6 +159,8 @@ stable_node_chains_prune_millisecs The effectiveness of KSM and MADV_MERGEABLE is shown in ``/sys/kernel/mm/ksm/``: +general_profit + how effective is KSM. The calculation is explained below. pages_shared how many shared pages are being used pages_sharing
Signature · 1 line
2.30.2
Re: [RFC PATCH v2 09/19] docs: document general_profit sysfs knob
Quoted 1 line · Stefan Roesch
Document
general_progitknob.
Book about Git :); it should have been general_profit.
Quoted 21 lines
Documentation/ABI/testing/sysfs-kernel-mm-ksm +8
-0@@ -51,3 +51,11 @@ Description: Control merging pages across different NUMA nodes. When it is set to 0 only pages from the same node are merged, otherwise pages from all nodes can be merged together (default). + +What: /sys/kernel/mm/ksm/general_profit +Date: January 2023 +KernelVersion: 6.1 +Contact: Linux memory management mailing list <[email protected]> +Description: Measure how effective KSM is. + general_profit: how effective is KSM. The formula for the + calculation is in Documentation/admin-guide/mm/ksm.rst.Documentation/admin-guide/mm/ksm.rst +0
-0
Documentation/admin-guide/mm/ksm.rst stable_node_chains_prune_millisecs · line 166
Quoted 8 lines
Documentation/admin-guide/mm/ksm.rst +2
-0@@ -159,6 +159,8 @@ stable_node_chains_prune_millisecs The effectiveness of KSM and MADV_MERGEABLE is shown in ``/sys/kernel/mm/ksm/``: +general_profit + how effective is KSM. The calculation is explained below. pages_shared how many shared pages are being used pages_sharing
LGTM, thanks!
Signature · 1 line
An old man doll... just what I always wanted! - Clara
Re: [RFC PATCH v2 09/19] docs: document general_profit sysfs knob
Quoted 5 lines · Bagas Sanjaya
Quoted 1 line · Stefan Roesch
Document
general_progitknob.Book about Git :); it should have been
general_profit.
Thanks, Fixed.
Quoted 33 lines
Quoted 21 lines
Documentation/ABI/testing/sysfs-kernel-mm-ksm +8
-0@@ -51,3 +51,11 @@ Description: Control merging pages across different NUMA nodes. When it is set to 0 only pages from the same node are merged, otherwise pages from all nodes can be merged together (default). + +What: /sys/kernel/mm/ksm/general_profit +Date: January 2023 +KernelVersion: 6.1 +Contact: Linux memory management mailing list <[email protected]> +Description: Measure how effective KSM is. + general_profit: how effective is KSM. The formula for the + calculation is in Documentation/admin-guide/mm/ksm.rst.Documentation/admin-guide/mm/ksm.rst +0
-0Documentation/admin-guide/mm/ksm.rst stable_node_chains_prune_millisecs · line 166
Quoted 8 lines
Documentation/admin-guide/mm/ksm.rst +2
-0@@ -159,6 +159,8 @@ stable_node_chains_prune_millisecs The effectiveness of KSM and MADV_MERGEABLE is shown in ``/sys/kernel/mm/ksm/``: +general_profit + how effective is KSM. The calculation is explained below. pages_shared how many shared pages are being used pages_sharingLGTM, thanks!
Reviewed-by Bagas Sanjaya <[email protected]>
RFC PATCH v2 10/19 mm: calculate ksm process profit metric
In reply to Stefan RoeschThe ksm documentation mentions the process profit metric and how to calculate it. This adds the calculation of the metric.
--- include/linux/ksm.h | 4 ++++ mm/ksm.c | 8 ++++++++ 2 files changed, 12 insertions(+)
include/linux/ksm.h +4 -0
@@ -55,6 +55,10 @@ struct page *ksm_might_need_to_copy(struct page *page,void rmap_walk_ksm (struct folio *folio,struct rmap_walk_control *rwc);void folio_migrate_ksm (struct folio *newfolio,struct folio *folio); +#ifdef CONFIG_PROC_FS +long ksm_process_profit (struct mm_struct *); +#endif /* CONFIG_PROC_FS */ +#else /* !CONFIG_KSM */ static inline int ksm_fork (struct mm_struct *mm,struct mm_struct *oldmm)
mm/ksm.c +8 -0
@@ -3024,6 +3024,14 @@ static void wait_while_offlining(void) }#endif /* CONFIG_MEMORY_HOTREMOVE */ +#ifdef CONFIG_PROC_FS +long ksm_process_profit (struct mm_struct *mm) +{ +return (long )mm->ksm_merging_pages *PAGE_SIZE - + mm->ksm_rmap_items *sizeof (struct ksm_rmap_item ); +} +#endif /* CONFIG_PROC_FS */ +#ifdef CONFIG_SYSFS /* * This all compiles without CONFIG_SYSFS, but is a waste of space.
Signature · 1 line
2.30.2
RFC PATCH v2 11/19 mm: add ksm_merge_type() function
In reply to Stefan RoeschThis adds the ksm_merge_type function. The function returns the merge type for the process. For madvise it returns "madvise", for prctl it returns "process" and otherwise it returns "none".
--- include/linux/ksm.h | 1 + mm/ksm.c | 11 +++++++++++ 2 files changed, 12 insertions(+)
include/linux/ksm.h +1 -0
@@ -57,6 +57,7 @@ void folio_migrate_ksm(struct folio *newfolio, struct folio *folio);#ifdef CONFIG_PROC_FS long ksm_process_profit (struct mm_struct *); +const char *ksm_merge_type (struct mm_struct *mm);#endif /* CONFIG_PROC_FS */ #else /* !CONFIG_KSM */
mm/ksm.c +11 -0
@@ -3030,6 +3030,17 @@ long ksm_process_profit(struct mm_struct *mm)return (long )mm->ksm_merging_pages *PAGE_SIZE - mm->ksm_rmap_items * sizeof(struct ksm_rmap_item); } + +/* Return merge type name as string. */ +const char *ksm_merge_type (struct mm_struct *mm) +{ +if (test_bit (MMF_VM_MERGE_ANY , &mm->flags)) +return "process" ; +else if (test_bit (MMF_VM_MERGEABLE , &mm->flags)) +return "madvise" ; +else +return "none" ; +}#endif /* CONFIG_PROC_FS */ #ifdef CONFIG_SYSFS
Signature · 1 line
2.30.2
RFC PATCH v2 12/19 mm: expose ksm process profit metric in ksm_stat
In reply to Stefan RoeschThis exposes the ksm process profit metric in /proc/<pid>/ksm_stat. The documentation mentions the formula for the ksm process profit metric, however it does not calculate it. In addition the formula depends on the size of internal structures. So it makes sense to expose it.
--- fs/proc/base.c | 3 +++ 1 file changed, 3 insertions(+)
fs/proc/base.c +3 -0
@@ -96,6 +96,7 @@#include <linux/time_namespace.h> #include <linux/resctrl.h> #include <linux/cn_proc.h> +#include <linux/ksm.h> #include <trace/events/oom.h> #include "internal.h" #include "fd.h"
@@ -3208,6 +3209,8 @@ static int proc_pid_ksm_stat(struct seq_file *m, struct pid_namespace *ns,if (mm) {seq_printf (m,"ksm_rmap_items %lu\n" , mm->ksm_rmap_items);seq_printf (m,"zero_pages_sharing %lu\n" , mm->ksm_zero_pages_sharing); +seq_printf (m,"ksm_merging_pages %lu\n" , mm->ksm_merging_pages); +seq_printf (m,"ksm_process_profit %ld\n" ,ksm_process_profit (mm));mmput (mm); }
Signature · 1 line
2.30.2
RFC PATCH v2 13/19 mm: expose ksm merge type in ksm_stat
In reply to Stefan RoeschThis exposes the ksm process type in /proc/<pid>/ksm_stat. The name of the value is ksm_merge_type.
--- fs/proc/base.c | 2 ++ 1 file changed, 2 insertions(+)
fs/proc/base.c +2 -0
@@ -3200,6 +3200,7 @@ static int proc_pid_ksm_merging_pages(struct seq_file *m, struct pid_namespace *return 0 ; } +static int proc_pid_ksm_stat (struct seq_file *m,struct pid_namespace *ns,struct pid *pid,struct task_struct *task) {
@@ -3210,6 +3211,7 @@ static int proc_pid_ksm_stat(struct seq_file *m, struct pid_namespace *ns,seq_printf (m,"ksm_rmap_items %lu\n" , mm->ksm_rmap_items);seq_printf (m,"zero_pages_sharing %lu\n" , mm->ksm_zero_pages_sharing);seq_printf (m,"ksm_merging_pages %lu\n" , mm->ksm_merging_pages); +seq_printf (m,"ksm_merge_type %s\n" ,ksm_merge_type (mm));seq_printf (m,"ksm_process_profit %ld\n" ,ksm_process_profit (mm));mmput (mm); }
Signature · 1 line
2.30.2
RFC PATCH v2 14/19 docs: document new procfs ksm knobs
In reply to Stefan RoeschDocument both ksm_process_profit and ksm_merge_type proc settings.
--- Documentation/admin-guide/mm/ksm.rst | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
Documentation/admin-guide/mm/ksm.rst +5 -1
@@ -218,7 +218,8 @@ several times, which are unprofitable memory consumed. ksm_rmap_items * sizeof(rmap_item). where ksm_merging_pages is shown under the directory ``/proc/<pid>/``, - and ksm_rmap_items is shown in ``/proc/<pid>/ksm_stat``. + and ksm_rmap_items is shown in ``/proc/<pid>/ksm_stat``. The process profit + is also shown in ``/proc/<pid>/ksm_stat`` as ksm_process_profit. From the perspective of application, a high ratio of ``ksm_rmap_items`` to ``ksm_merging_pages`` means a bad madvise-applied policy, so developers or
@@ -229,6 +230,9 @@ so if the ``ksm_rmap_items/ksm_merging_pages`` ratio exceeds 64 on 64-bit CPU or exceeds 128 on 32-bit CPU, then the app's madvise policy should be dropped, because the ksm profit is approximately zero or negative. +The ksm_merge_type in ``/proc/<pid>/ksm_stat`` shows the merge type of the +process. Valid values are ``none``, ``madvise`` and ``process``. + Monitoring KSM events =====================
Signature · 1 line
2.30.2
Re: [RFC PATCH v2 14/19] docs: document new procfs ksm knobs
Quoted 15 lines · Stefan Roesch
Documentation/admin-guide/mm/ksm.rst +2
-1@@ -218,7 +218,8 @@ several times, which are unprofitable memory consumed. ksm_rmap_items * sizeof(rmap_item). where ksm_merging_pages is shown under the directory ``/proc/<pid>/``, - and ksm_rmap_items is shown in ``/proc/<pid>/ksm_stat``. + and ksm_rmap_items is shown in ``/proc/<pid>/ksm_stat``. The process profit + is also shown in ``/proc/<pid>/ksm_stat`` as ksm_process_profit. From the perspective of application, a high ratio of ``ksm_rmap_items`` to ``ksm_merging_pages`` means a bad madvise-applied policy, so developers or
Documentation/admin-guide/mm/ksm.rst so if the ``ksm_rmap_items/ksm_merging_pages`` ratio exceeds 64 on 64-bit CPU · line 238
Quoted 9 lines
Documentation/admin-guide/mm/ksm.rst +3
-0@@ -229,6 +230,9 @@ so if the ``ksm_rmap_items/ksm_merging_pages`` ratio exceeds 64 on 64-bit CPU or exceeds 128 on 32-bit CPU, then the app's madvise policy should be dropped, because the ksm profit is approximately zero or negative. +The ksm_merge_type in ``/proc/<pid>/ksm_stat`` shows the merge type of the +process. Valid values are ``none``, ``madvise`` and ``process``. + Monitoring KSM events =====================
LGTM, thanks!
Signature · 1 line
An old man doll... just what I always wanted! - Clara
RFC PATCH v2 15/19 tools: add new prctl flags to prctl in tools dir
In reply to Stefan RoeschThis adds the new prctl flags to the include file prct.h in the tools directory. This makes sure they are available for testing.
--- tools/include/uapi/linux/prctl.h | 2 ++ 1 file changed, 2 insertions(+)
tools/include/uapi/linux/prctl.h +2 -0
@@ -284,4 +284,6 @@ struct prctl_mm_map {#define PR_SET_VMA 0x53564d41# define PR_SET_VMA_ANON_NAME 0 +#define PR_SET_MEMORY_MERGE 67 +#define PR_GET_MEMORY_MERGE 68#endif /* _LINUX_PRCTL_H */
Signature · 1 line
2.30.2
RFC PATCH v2 16/19 selftests/vm: add KSM prctl merge test
In reply to Stefan RoeschThis adds the -t option to the ksm_tests program. The -t flag allows to specify if it should use madvise or prctl ksm merging.
--- tools/testing/selftests/mm/Makefile | 3 +- tools/testing/selftests/mm/ksm_tests.c | 116 +++++++++++++++++-------- 2 files changed, 80 insertions(+), 39 deletions(-)
tools/testing/selftests/mm/Makefile +2 -1
@@ -29,7 +29,8 @@ MACHINE ?= $(shell echo $(uname_M) | sed -e 's/aarch64.*/arm64/' -e 's/ppc64.*/p # LDLIBS. MAKEFLAGS += --no-builtin-rules -CFLAGS = -Wall -I $(top_srcdir) -I $(top_srcdir)/usr/include $(EXTRA_CFLAGS) $(KHDR_INCLUDES) +CFLAGS = -Wall -I $(top_srcdir)/tools/include/uapi +CFLAGS += -I $(top_srcdir) -I $(top_srcdir)/usr/include $(EXTRA_CFLAGS) $(KHDR_INCLUDES) LDLIBS = -lrt -lpthread TEST_GEN_FILES = cow TEST_GEN_FILES += compaction_test
tools/testing/selftests/mm/ksm_tests.c +78 -38
301 lines not on this page · raw message
Signature · 1 line
2.30.2
RFC PATCH v2 17/19 selftests/vm: add KSM get merge type test
In reply to Stefan RoeschThis adds the -G flag to the ksm_tests to query if prctl has been used to enable ksm merging.
--- tools/testing/selftests/mm/ksm_tests.c | 37 ++++++++++++++++++++++++-- 1 file changed, 35 insertions(+), 2 deletions(-)
tools/testing/selftests/mm/ksm_tests.c +35 -2
@@ -45,6 +45,7 @@ enum ksm_merge_type {enum ksm_test_name {CHECK_KSM_MERGE ,CHECK_KSM_UNMERGE , +CHECK_KSM_GET_MERGE_TYPE ,CHECK_KSM_ZERO_PAGE_MERGE ,CHECK_KSM_NUMA_MERGE ,KSM_MERGE_TIME ,
@@ -124,7 +125,8 @@ static void print_help(void)" -D evaluate unmerging time and speed when disabling KSM.\n" " For this test, the size of duplicated memory area (in MiB)\n" " must be provided using -s option\n" - " -C evaluate the time required to break COW of merged pages.\n\n"); +" -C evaluate the time required to break COW of merged pages.\n" + " -G query merge mode\n\n");printf (" -a: specify the access protections of pages.\n" " <prot> must be of the form [rwx].\n"
@@ -323,6 +325,31 @@ static int check_ksm_merge(int merge_type, int mapping, int prot,return KSFT_FAIL ; } +static int check_ksm_get_merge_type (void ) +{ +if (prctl (PR_SET_MEMORY_MERGE ,1 )) { +perror ("prctl set" ); +return 1 ; + } + +int is_on =prctl (PR_GET_MEMORY_MERGE ,0 ); + +if (prctl (PR_SET_MEMORY_MERGE ,0 )) { +perror ("prctl set" ); +return 1 ; + } + +int is_off =prctl (PR_GET_MEMORY_MERGE ,0 ); + +if (is_on && is_off) { +printf ("OK\n" ); +return KSFT_PASS ; + } + +printf ("Not OK\n" ); +return KSFT_FAIL ; +} +static int check_ksm_unmerge (int merge_type,int mapping,int prot,int timeout,size_t page_size) {void *map_ptr;
@@ -733,7 +760,7 @@ int main(int argc, char *argv[])bool merge_across_nodes =KSM_MERGE_ACROSS_NODES_DEFAULT ;long size_MB =0 ; -while ((opt =getopt (argc, argv,"ha:p:l:z:m:s:t:MUZNPCHD" )) !=-1 ) { +while ((opt =getopt (argc, argv,"ha:p:l:z:m:s:t:GMUZNPCHD" )) !=-1 ) {switch (opt) {case 'a' : prot =str_to_prot (optarg);
@@ -792,6 +819,9 @@ int main(int argc, char *argv[])case 'Z' : test_name =CHECK_KSM_ZERO_PAGE_MERGE ;break ; +case 'G' : + test_name =CHECK_KSM_GET_MERGE_TYPE ; +break ;case 'N' : test_name =CHECK_KSM_NUMA_MERGE ;break ;
@@ -841,6 +871,9 @@ int main(int argc, char *argv[]) ret =check_ksm_unmerge (merge_type,MAP_PRIVATE |MAP_ANONYMOUS , prot, ksm_scan_limit_sec, page_size);break ; +case CHECK_KSM_GET_MERGE_TYPE : + ret =check_ksm_get_merge_type (); +break ;case CHECK_KSM_ZERO_PAGE_MERGE : ret = check_ksm_zero_page_merge(merge_type, MAP_PRIVATE | MAP_ANONYMOUS, prot, page_count, ksm_scan_limit_sec, use_zero_pages,
Signature · 1 line
2.30.2
RFC PATCH v2 18/19 selftests/vm: add KSM fork test
In reply to Stefan RoeschAdd fork test to verify that the MMF_VM_MERGE_ANY flag is inherited by the child process.
--- tools/testing/selftests/mm/ksm_tests.c | 53 +++++++++++++++++++++++++- 1 file changed, 51 insertions(+), 2 deletions(-)
tools/testing/selftests/mm/ksm_tests.c +51 -2
@@ -44,6 +44,7 @@ enum ksm_merge_type {enum ksm_test_name {CHECK_KSM_MERGE , +CHECK_KSM_MERGE_FORK ,CHECK_KSM_UNMERGE ,CHECK_KSM_GET_MERGE_TYPE ,CHECK_KSM_ZERO_PAGE_MERGE ,
@@ -126,7 +127,8 @@ static void print_help(void)" For this test, the size of duplicated memory area (in MiB)\n" " must be provided using -s option\n" " -C evaluate the time required to break COW of merged pages.\n" - " -G query merge mode\n\n"); +" -G query merge mode\n" + " -F evaluate that the KSM process flag is inherited\n\n");printf (" -a: specify the access protections of pages.\n" " <prot> must be of the form [rwx].\n"
@@ -325,6 +327,47 @@ static int check_ksm_merge(int merge_type, int mapping, int prot,return KSFT_FAIL ; } +/* Verify that prctl ksm flag is inherited. */ +static int check_ksm_fork (void ) +{ +int rc =KSFT_FAIL ; +pid_t child_pid; + +if (prctl (PR_SET_MEMORY_MERGE ,1 )) { +perror ("prctl" ); +return KSFT_FAIL ; + } + + child_pid =fork (); +if (child_pid ==0 ) { +int is_on =prctl (PR_GET_MEMORY_MERGE ,0 ); + +if (!is_on) +exit (KSFT_FAIL ); + +exit (KSFT_PASS ); + } + +if (child_pid <0 ) + goto out; + +if (waitpid (child_pid, &rc,0 ) <0 ) + rc =KSFT_FAIL ; + +if (prctl (PR_SET_MEMORY_MERGE ,0 )) { +perror ("prctl" ); + rc =KSFT_FAIL ; + } + +out: +if (rc ==KSFT_PASS ) +printf ("OK\n" ); +else +printf ("Not OK\n" ); + +return rc; +} +static int check_ksm_get_merge_type (void ) {if (prctl (PR_SET_MEMORY_MERGE ,1 )) {
@@ -760,7 +803,7 @@ int main(int argc, char *argv[])bool merge_across_nodes =KSM_MERGE_ACROSS_NODES_DEFAULT ;long size_MB =0 ; -while ((opt =getopt (argc, argv,"ha:p:l:z:m:s:t:GMUZNPCHD" )) !=-1 ) { +while ((opt =getopt (argc, argv,"ha:p:l:z:m:s:t:FGMUZNPCHD" )) !=-1 ) {switch (opt) {case 'a' : prot =str_to_prot (optarg);
@@ -811,6 +854,9 @@ int main(int argc, char *argv[]) merge_type =atoi (optarg); }break ; +case 'F' : + test_name =CHECK_KSM_MERGE_FORK ; +break ;case 'M' :break ;case 'U' :
@@ -867,6 +913,9 @@ int main(int argc, char *argv[]) ret =check_ksm_merge (merge_type,MAP_PRIVATE |MAP_ANONYMOUS , prot, page_count, ksm_scan_limit_sec, page_size);break ; +case CHECK_KSM_MERGE_FORK : + ret =check_ksm_fork (); +break ;case CHECK_KSM_UNMERGE : ret =check_ksm_unmerge (merge_type,MAP_PRIVATE |MAP_ANONYMOUS , prot, ksm_scan_limit_sec, page_size);
Signature · 1 line
2.30.2
RFC PATCH v2 19/19 selftests/vm: add two functions for debugging merge outcome
In reply to Stefan RoeschThis adds two functions to report the metrics in /proc/self/ksm_stat and /sys/kernel/debug/mm/ksm.
The debugging can be enabled with the following command line:
make -C tools/testing/selftests TARGETS="vm" --keep-going \
EXTRA_CFLAGS=-DDEBUG=1
--- tools/testing/selftests/mm/ksm_tests.c | 54 ++++++++++++++++++++++++++ 1 file changed, 54 insertions(+)
tools/testing/selftests/mm/ksm_tests.c +54 -0
@@ -93,6 +93,55 @@ static int ksm_read_sysfs(const char *file_path, unsigned long *val)return 0 ; } +#ifdef DEBUG +static void ksm_print_sysfs (void ) +{ +unsigned long max_page_sharing, pages_sharing, pages_shared; +unsigned long full_scans, pages_unshared, pages_volatile; +unsigned long stable_node_chains, stable_node_dups; +long general_profit; + +if (ksm_read_sysfs (KSM_FP ("pages_shared" ), &pages_shared) || +ksm_read_sysfs (KSM_FP ("pages_sharing" ), &pages_sharing) || +ksm_read_sysfs (KSM_FP ("max_page_sharing" ), &max_page_sharing) || +ksm_read_sysfs (KSM_FP ("full_scans" ), &full_scans) || +ksm_read_sysfs (KSM_FP ("pages_unshared" ), &pages_unshared) || +ksm_read_sysfs (KSM_FP ("pages_volatile" ), &pages_volatile) || +ksm_read_sysfs (KSM_FP ("stable_node_chains" ), &stable_node_chains) || +ksm_read_sysfs (KSM_FP ("stable_node_dups" ), &stable_node_dups) || +ksm_read_sysfs (KSM_FP ("general_profit" ), (unsigned long *)&general_profit)) +return ; + +printf ("pages_shared : %lu\n" , pages_shared); +printf ("pages_sharing : %lu\n" , pages_sharing); +printf ("max_page_sharing : %lu\n" , max_page_sharing); +printf ("full_scans : %lu\n" , full_scans); +printf ("pages_unshared : %lu\n" , pages_unshared); +printf ("pages_volatile : %lu\n" , pages_volatile); +printf ("stable_node_chains: %lu\n" , stable_node_chains); +printf ("stable_node_dups : %lu\n" , stable_node_dups); +printf ("general_profit : %ld\n" , general_profit); +} + +static void ksm_print_procfs (void ) +{ +const char *file_name ="/proc/self/ksm_stat" ; +char buffer[512 ]; +FILE *f =fopen (file_name,"r" ); + +if (!f) { +fprintf (stderr,"f %s\n" , file_name); +perror ("fopen" ); +return ; + } + +while (fgets (buffer,sizeof (buffer), f)) +printf ("%s" , buffer); + +fclose (f); +} +#endif +static int str_to_prot (char *prot_str) {int prot =0 ;
@@ -237,6 +286,11 @@ static bool assert_ksm_pages_count(long dupl_page_count) ksm_read_sysfs(KSM_FP("max_page_sharing"), &max_page_sharing))return false; +#ifdef DEBUG +ksm_print_sysfs (); +ksm_print_procfs (); +#endif +/* * Since there must be at least 2 pages for merging and 1 page can be * shared with the limited number of pages (max_page_sharing), sometimes
Signature · 1 line
2.30.2
Quoted 4 lines · Stefan Roesch
So far KSM can only be enabled by calling madvise for memory regions. What is required to enable KSM for more workloads is to enable / disable it at the process / cgroup level.
Quoted 8 lines
Use case:
The madvise call is not available in the programming language. An example for this are programs with forked workloads using a garbage collected language without pointers. In such a language madvise cannot be made available.In addition the addresses of objects get moved around as they are garbage collected. KSM sharing needs to be enabled "from the outside" for these type of workloads.
Don't you have source code to the interpreter for this mysterious language? Usually that would be where we put calls to madvise()
Quoted 14 lines · Matthew Wilcox
Quoted 13 lines · Stefan Roesch
So far KSM can only be enabled by calling madvise for memory regions. What is
required to enable KSM for more workloads is to enable / disable it at the
process / cgroup level.Use case:
The madvise call is not available in the programming language. An example for
this are programs with forked workloads using a garbage collected language without
pointers. In such a language madvise cannot be made available.
Quoted 8 lines
Quoted 5 lines
In addition the addresses of objects get moved around as they are garbage
collected. KSM sharing needs to be enabled "from the outside" for these type of
workloads.Don't you have source code to the interpreter for this mysterious language? Usually that would be where we put calls to
madvise()
That same interpreter is also used for workloads where KSM brings no benefit, and we don't want the overhead of KSM.
It really would be useful to have the ability to enable this on a per workload basis, for programming languages that do not support madvise.
Signature · 1 line
All Rights Reversed.
Hi Stefan,
Quoted 4 lines · Stefan Roesch
So far KSM can only be enabled by calling madvise for memory regions. What is required to enable KSM for more workloads is to enable / disable it at the process / cgroup level.
Quoted 8 lines
Use case:
The madvise call is not available in the programming language. An example for this are programs with forked workloads using a garbage collected language without pointers. In such a language madvise cannot be made available.In addition the addresses of objects get moved around as they are garbage collected. KSM sharing needs to be enabled "from the outside" for these type of workloads.
It would be good to expand on the argument that Rik made about the interpreter being used for things were there are no merging opportunities, and the KSM scanning overhead isn't amortized.
There is a fundamental mismatch in scopes. madvise() is a workload-local decision, whereas sizable sharing opportunities may or may not exist across multiple workloads. Only a higher-level entity like a job scheduler can know for certain whether it's running one or more instances of a job. That job scheduler in turn doesn't have the necessary knowledge of the workload's internals to make targeted and well-timed advise calls with, say, process_madvise().
This also applies to the security concerns brought up in previous threads. An individual workload doesn't know what else is running on the machine, so it needs to be highly conservative about what it can give up for system-wide merging. However, if the system is dedicated to running multiple jobs within the same security domain, it's the job scheduler that knows that sharing isn't a problem, and even desirable.
So I think this series makes sense, but it would be good to expand a bit on the reasoning and address the security aspect in the cover/doc.
Quoted 7 lines
Stefan Roesch (19):
mm: add new flag to enable ksm per process
mm: add flag to__ksm_enter
mm: add flag to__ksm_exitcall
mm: invoke madvise for all vmas inscan_get_next_rmap_item
mm: support disabling of ksm for a process
mm: add new prctl option to get and set ksm for a process
The implementation looks sound to me as well.
I think it would be a bit easier to review if you folded these ^^^ patches, the tools patch below, and the prctl selftests, all into one single commit. It's one logical change. This way the new flags and helper functions can be reviewed against the new users and callsites without having to jump back and forth between emails.
Quoted 8 lines
mm: split off
pages_volatilefunction
mm: exposegeneral_profitmetric
docs: documentgeneral_profitsysfs knob
mm: calculate ksm process profit metric
mm: addksm_merge_type()function
mm: expose ksm process profit metric inksm_stat
mm: expose ksm merge type inksm_stat
docs: document new procfs ksm knobs
Same with the new knobs/stats and their documentation.
Logical splitting is easier to follow than geographical splitting.
Thanks!
Quoted 35 lines · Johannes Weiner
Hi Stefan,
Quoted 4 lines · Stefan Roesch
So far KSM can only be enabled by calling madvise for memory regions. What is required to enable KSM for more workloads is to enable / disable it at the process / cgroup level.
Quoted 8 lines
Use case:
The madvise call is not available in the programming language. An example for this are programs with forked workloads using a garbage collected language without pointers. In such a language madvise cannot be made available.In addition the addresses of objects get moved around as they are garbage collected. KSM sharing needs to be enabled "from the outside" for these type of workloads.
It would be good to expand on the argument that Rik made about the interpreter being used for things were there are no merging opportunities, and the KSM scanning overhead isn't amortized.
There is a fundamental mismatch in scopes.
madvise()is a workload-local decision, whereas sizable sharing opportunities may or may not exist across multiple workloads. Only a higher-level entity like a job scheduler can know for certain whether it's running one or more instances of a job. That job scheduler in turn doesn't have the necessary knowledge of the workload's internals to make targeted and well-timed advise calls with, say,process_madvise().This also applies to the security concerns brought up in previous threads. An individual workload doesn't know what else is running on the machine, so it needs to be highly conservative about what it can give up for system-wide merging. However, if the system is dedicated to running multiple jobs within the same security domain, it's the job scheduler that knows that sharing isn't a problem, and even desirable.
Quoted 3 lines
So I think this series makes sense, but it would be good to expand a bit on the reasoning and address the security aspect in the cover/doc.
These are good points Johannes, I'll elaborate on them with the next version of the patch.
Quoted 8 lines
Quoted 7 lines
Stefan Roesch (19):
mm: add new flag to enable ksm per process
mm: add flag to__ksm_enter
mm: add flag to__ksm_exitcall
mm: invoke madvise for all vmas inscan_get_next_rmap_item
mm: support disabling of ksm for a process
mm: add new prctl option to get and set ksm for a process
Quoted 8 lines
The implementation looks sound to me as well.
I think it would be a bit easier to review if you folded these ^^^ patches, the tools patch below, and the prctl selftests, all into one single commit. It's one logical change. This way the new flags and helper functions can be reviewed against the new users and callsites without having to jump back and forth between emails.
I'll fold them in the next version.
Quoted 11 lines
Quoted 8 lines
mm: split off
pages_volatilefunction
mm: exposegeneral_profitmetric
docs: documentgeneral_profitsysfs knob
mm: calculate ksm process profit metric
mm: addksm_merge_type()function
mm: expose ksm process profit metric inksm_stat
mm: expose ksm merge type inksm_stat
docs: document new procfs ksm knobsSame with the new knobs/stats and their documentation.
I'll fold them in the next version.
Quoted 3 lines
Logical splitting is easier to follow than geographical splitting.
Thanks!