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create /proc/timer-wheel-list

PATCH In review Joe Korty 8 participants 19 messages Nov 21, 2008 – Dec 5, 2008

Subsystems (2)
ABI/API High-resolution timers, timer wheel, clockevents
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Joe Korty

author
#0 lore raw

PATCH 1/1 create /proc/timer-wheel-list

Create /proc/timer_wheel_list.

This does for the timer wheel what /proc/timer_list does for hrtimers -- provide a way of displaying what timers are running on what cpus, and their attributes.

Signed-off-by Joe Korty <[email protected]>
kernel/timer.c +109 -0
Index: 2.6.28-rc6/kernel/timer.c
===================================================================
@@ -36,6 +36,8 @@
 #include <linux/syscalls.h>
 #include <linux/delay.h>
 #include <linux/tick.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
 #include <linux/kallsyms.h>
 
 #include <asm/uaccess.h>

@@ -1568,6 +1570,113 @@
 	open_softirq(TIMER_SOFTIRQ, run_timer_softirq);
 }
 
+#ifdef CONFIG_PROC_FS
+
+static void seq_printf_symbol(struct seq_file *m, void *symaddr, int width)
+{
+	char symname[KSYM_NAME_LEN];
+	int stat, len = m->count;
+
+	if (lookup_symbol_name((unsigned long)symaddr, symname) < 0)
+		stat = seq_printf(m, "<%p>", symaddr);
+	else
+		stat = seq_printf(m, "%s", symname);
+	if (width && stat == 0) {
+		len += (width - m->count);
+		if (len > 0)
+			seq_printf(m, "%*s", len, " ");
+	}
+}
+
+static void print_single_timer(struct seq_file *m, struct timer_list *timer)
+{
+	unsigned long base_jiffies = tbase_get_base(timer->base)->timer_jiffies;
+
+	seq_printf(m, " %p - ", (void *)(timer->expires - base_jiffies));
+	seq_printf_symbol(m, timer->function, 24);
+	seq_printf(m, " (data ");
+	seq_printf_symbol(m, (void *)(timer->data), 24);
+	seq_printf(m, ")");
+#ifdef CONFIG_TIMER_STATS
+	seq_printf(m, " from ");
+	seq_printf_symbol(m, timer->start_site, 28);
+	seq_printf(m, " %*s/%d",
+		TASK_COMM_LEN, timer->start_comm,
+		timer->start_pid);
+#endif
+	seq_printf(m, "\n");
+}
+
+static void print_timer_list(struct seq_file *m, struct list_head *head)
+{
+	struct timer_list *timer;
+	struct list_head *item;
+
+	for (item = head->next; item != head; item = item->next) {
+		timer = list_entry(item, struct timer_list, entry);
+		print_single_timer(m, timer);
+	}
+}
+
+static void print_cpu_timers(struct seq_file *m, int cpu)
+{
+	int i;
+	struct tvec_base *base = per_cpu(tvec_bases, cpu);
+
+	spin_lock_irq(&base->lock);
+	seq_printf(m, "\ncpu: %d, base jiffies: %p\n\n",
+		cpu, (void *)(base->timer_jiffies));
+
+	for (i = 0; i < TVR_SIZE; i++)
+		print_timer_list(m, base->tv1.vec + i);
+	for (i = 0; i < TVN_SIZE; i++) {
+		print_timer_list(m, base->tv2.vec + i);
+		print_timer_list(m, base->tv3.vec + i);
+		print_timer_list(m, base->tv4.vec + i);
+		print_timer_list(m, base->tv5.vec + i);
+	}
+	spin_unlock_irq(&base->lock);
+}
+
+static int timer_list_show(struct seq_file *m, void *v)
+{
+	int cpu;
+
+	seq_printf(m, "Timer Wheel List Version: 1\n");
+	seq_printf(m, "Jiffies: %px\n", (void *)jiffies);
+
+	for_each_online_cpu(cpu) {
+		print_cpu_timers(m, cpu);
+	}
+
+	return 0;
+}
+
+static int timer_list_open(struct inode *inode, struct file *filp)
+{
+	return single_open(filp, timer_list_show, NULL);
+}
+
+static struct file_operations timer_list_fops = {
+	.open		= timer_list_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= single_release,
+};
+
+static int __init init_timer_list_procfs(void)
+{
+	struct proc_dir_entry *pe;
+
+	pe = proc_create("timer_wheel_list", 0444, NULL, &timer_list_fops);
+	if (!pe)
+		return -ENOMEM;
+	return 0;
+}
+late_initcall(init_timer_list_procfs);
+
+#endif /* CONFIG_PROC_FS */
+
 /**
  * msleep - sleep safely even with waitqueue interruptions
  * @msecs: Time in milliseconds to sleep for
#1 lore raw
Quoted 5 lines · Joe Korty

Create /proc/timer_wheel_list.

This does for the timer wheel what /proc/timer_list does for hrtimers -- provide a way of displaying what timers are running on what cpus, and their attributes.

The fact that it's called a timer wheel is just an implementation detail unsuitable for permanent file.

And you invented totally new (broken) way to print jiffies.

For printing nice function pointers we have %pF now.

late_initcall usage is taken out of air.

Can we put all this shit in debugfs, please?

Quoted 112 lines
kernel/timer.c +106 -0
@@ -1568,6 +1570,113 @@
 	open_softirq(TIMER_SOFTIRQ, run_timer_softirq);
 }
 
+#ifdef CONFIG_PROC_FS
+
+static void seq_printf_symbol(struct seq_file *m, void *symaddr, int width)
+{
+	char symname[KSYM_NAME_LEN];
+	int stat, len = m->count;
+
+	if (lookup_symbol_name((unsigned long)symaddr, symname) < 0)
+		stat = seq_printf(m, "<%p>", symaddr);
+	else
+		stat = seq_printf(m, "%s", symname);
+	if (width && stat == 0) {
+		len += (width - m->count);
+		if (len > 0)
+			seq_printf(m, "%*s", len, " ");
+	}
+}
+
+static void print_single_timer(struct seq_file *m, struct timer_list *timer)
+{
+	unsigned long base_jiffies = tbase_get_base(timer->base)->timer_jiffies;
+
+	seq_printf(m, " %p - ", (void *)(timer->expires - base_jiffies));
+	seq_printf_symbol(m, timer->function, 24);
+	seq_printf(m, " (data ");
+	seq_printf_symbol(m, (void *)(timer->data), 24);
+	seq_printf(m, ")");
+#ifdef CONFIG_TIMER_STATS
+	seq_printf(m, " from ");
+	seq_printf_symbol(m, timer->start_site, 28);
+	seq_printf(m, " %*s/%d",
+		TASK_COMM_LEN, timer->start_comm,
+		timer->start_pid);
+#endif
+	seq_printf(m, "\n");
+}
+
+static void print_timer_list(struct seq_file *m, struct list_head *head)
+{
+	struct timer_list *timer;
+	struct list_head *item;
+
+	for (item = head->next; item != head; item = item->next) {
+		timer = list_entry(item, struct timer_list, entry);
+		print_single_timer(m, timer);
+	}
+}
+
+static void print_cpu_timers(struct seq_file *m, int cpu)
+{
+	int i;
+	struct tvec_base *base = per_cpu(tvec_bases, cpu);
+
+	spin_lock_irq(&base->lock);
+	seq_printf(m, "\ncpu: %d, base jiffies: %p\n\n",
+		cpu, (void *)(base->timer_jiffies));
+
+	for (i = 0; i < TVR_SIZE; i++)
+		print_timer_list(m, base->tv1.vec + i);
+	for (i = 0; i < TVN_SIZE; i++) {
+		print_timer_list(m, base->tv2.vec + i);
+		print_timer_list(m, base->tv3.vec + i);
+		print_timer_list(m, base->tv4.vec + i);
+		print_timer_list(m, base->tv5.vec + i);
+	}
+	spin_unlock_irq(&base->lock);
+}
+
+static int timer_list_show(struct seq_file *m, void *v)
+{
+	int cpu;
+
+	seq_printf(m, "Timer Wheel List Version: 1\n");
+	seq_printf(m, "Jiffies: %px\n", (void *)jiffies);
+
+	for_each_online_cpu(cpu) {
+		print_cpu_timers(m, cpu);
+	}
+
+	return 0;
+}
+
+static int timer_list_open(struct inode *inode, struct file *filp)
+{
+	return single_open(filp, timer_list_show, NULL);
+}
+
+static struct file_operations timer_list_fops = {
+	.open		= timer_list_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= single_release,
+};
+
+static int __init init_timer_list_procfs(void)
+{
+	struct proc_dir_entry *pe;
+
+	pe = proc_create("timer_wheel_list", 0444, NULL, &timer_list_fops);
+	if (!pe)
+		return -ENOMEM;
+	return 0;
+}
+late_initcall(init_timer_list_procfs);
+
+#endif /* CONFIG_PROC_FS */
author
#2 lore raw
Quoted 9 lines · Alexey Dobriyan
Quoted 5 lines · Joe Korty

Create /proc/timer_wheel_list.

This does for the timer wheel what /proc/timer_list does for hrtimers -- provide a way of displaying what timers are running on what cpus, and their attributes.

The fact that it's called a timer wheel is just an implementation detail unsuitable for permanent file.

Agreed. I'll come up with something else. lrtimer_list is a good candidate.

Quoted 1 line

And you invented totally new (broken) way to print jiffies.

You'll have to be more explicit about what's broken.

Quoted 1 line

For printing nice function pointers we have %pF now.

I'll go play with that again. IIRC, the first time I played with it, it's output was of the form 'symbol+0xoffset/0xsize' rather than just 'symbol'.

Quoted 1 line

late_initcall usage is taken out of air.

I'm open to suggestions. My thought was that it was as good as any other initcall, since none of this stuff can be referenced until after applications start running off of /sbin/init. So what one picks is a bit of a crapshoot.

Quoted 1 line

Can we put all this shit in debugfs, please?

I kinda like the debugfs idea. Though there is some attraction to making it parallel to the existing /proc/timer_list, rather than putting it somewhere else entirely.

I can see a migration path here .. put lrtimers_list in debugfs, later move /proc/timers_list to debugfs (perhaps as hrtimers_list) and make /proc/timers_list itself a symbolic link to the debugfs version.

Regards,
Joe

#3 lore raw
Quoted 8 lines · Joe Korty
Quoted 7 lines · Alexey Dobriyan
Quoted 5 lines · Joe Korty

Create /proc/timer_wheel_list.

This does for the timer wheel what /proc/timer_list does for hrtimers -- provide a way of displaying what timers are running on what cpus, and their attributes.

Quoted 5 lines
Quoted 2 lines

The fact that it's called a timer wheel is just an implementation detail unsuitable for permanent file.

Agreed. I'll come up with something else. lrtimer_list is a good candidate.

no - please include it in /proc/timer_list instead. It already lists clockevents and hrtimers - listing timer-list timers would be a natural extension of that facility.

Ingo

author
#4 lore raw
Quoted 14 lines · Ingo Molnar
Quoted 11 lines · Joe Korty
Quoted 9 lines · Alexey Dobriyan
Quoted 5 lines · Joe Korty

Create /proc/timer_wheel_list.

This does for the timer wheel what /proc/timer_list does for hrtimers -- provide a way of displaying what timers are running on what cpus, and their attributes.

The fact that it's called a timer wheel is just an implementation detail unsuitable for permanent file.

Quoted 6 lines
Quoted 2 lines

Agreed. I'll come up with something else. lrtimer_list is a good candidate.

no - please include it in /proc/timer_list instead. It already lists clockevents and hrtimers - listing timer-list timers would be a natural extension of that facility.

struct tvec_base and TVR_MASK & family are all local to kernel/timers.c rather than in some header file, so parts of the display code would need to remain in kernel/timers.c. Seems ugly, but is of course do-able.

Also, I am not sure why we are lumping all sorts of disparate things in one display file. Did proc files become expensive somewhere along the line?

(Just asking before I go down a path that everyone will hate, once they see the result).

Regards,
Joe

#5 lore raw
In reply to Joe Korty

Joe,

Quoted 5 lines · Joe Korty

Create /proc/timer_wheel_list.

This does for the timer wheel what /proc/timer_list does for hrtimers -- provide a way of displaying what timers are running on what cpus, and their attributes.

Please CC linux-api on kernel-userland API changes.

See Documentation/SubmitChecklist and
http://thread.gmane.org/gmane.linux.ltp/5658.

Cheers,

Michael

Quoted 133 lines

Index: 2.6.28-rc6/kernel/timer.c
===================================================================

kernel/timer.c 2008-11-21 17:04:25.000000000 -0500 renamed from kernel/timer.c 2008-11-21 17:02:04.000000000 -0500 +109 -1
@@ -36,6 +36,8 @@
 #include <linux/syscalls.h>
 #include <linux/delay.h>
 #include <linux/tick.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
 #include <linux/kallsyms.h>
 
 #include <asm/uaccess.h>

@@ -1568,6 +1570,113 @@
       open_softirq(TIMER_SOFTIRQ, run_timer_softirq);
 }
 
+#ifdef CONFIG_PROC_FS
+
+static void seq_printf_symbol(struct seq_file *m, void *symaddr, int width)
+{
+       char symname[KSYM_NAME_LEN];
+       int stat, len = m->count;
+
+       if (lookup_symbol_name((unsigned long)symaddr, symname) < 0)
+               stat = seq_printf(m, "<%p>", symaddr);
+       else
+               stat = seq_printf(m, "%s", symname);
+       if (width && stat == 0) {
+               len += (width - m->count);
+               if (len > 0)
+                       seq_printf(m, "%*s", len, " ");
+       }
+}
+
+static void print_single_timer(struct seq_file *m, struct timer_list *timer)
+{
+       unsigned long base_jiffies = tbase_get_base(timer->base)->timer_jiffies;
+
+       seq_printf(m, " %p - ", (void *)(timer->expires - base_jiffies));
+       seq_printf_symbol(m, timer->function, 24);
+       seq_printf(m, " (data ");
+       seq_printf_symbol(m, (void *)(timer->data), 24);
+       seq_printf(m, ")");
+#ifdef CONFIG_TIMER_STATS
+       seq_printf(m, " from ");
+       seq_printf_symbol(m, timer->start_site, 28);
+       seq_printf(m, " %*s/%d",
+               TASK_COMM_LEN, timer->start_comm,
+               timer->start_pid);
+#endif
+       seq_printf(m, "\n");
+}
+
+static void print_timer_list(struct seq_file *m, struct list_head *head)
+{
+       struct timer_list *timer;
+       struct list_head *item;
+
+       for (item = head->next; item != head; item = item->next) {
+               timer = list_entry(item, struct timer_list, entry);
+               print_single_timer(m, timer);
+       }
+}
+
+static void print_cpu_timers(struct seq_file *m, int cpu)
+{
+       int i;
+       struct tvec_base *base = per_cpu(tvec_bases, cpu);
+
+       spin_lock_irq(&base->lock);
+       seq_printf(m, "\ncpu: %d, base jiffies: %p\n\n",
+               cpu, (void *)(base->timer_jiffies));
+
+       for (i = 0; i < TVR_SIZE; i++)
+               print_timer_list(m, base->tv1.vec + i);
+       for (i = 0; i < TVN_SIZE; i++) {
+               print_timer_list(m, base->tv2.vec + i);
+               print_timer_list(m, base->tv3.vec + i);
+               print_timer_list(m, base->tv4.vec + i);
+               print_timer_list(m, base->tv5.vec + i);
+       }
+       spin_unlock_irq(&base->lock);
+}
+
+static int timer_list_show(struct seq_file *m, void *v)
+{
+       int cpu;
+
+       seq_printf(m, "Timer Wheel List Version: 1\n");
+       seq_printf(m, "Jiffies: %px\n", (void *)jiffies);
+
+       for_each_online_cpu(cpu) {
+               print_cpu_timers(m, cpu);
+       }
+
+       return 0;
+}
+
+static int timer_list_open(struct inode *inode, struct file *filp)
+{
+       return single_open(filp, timer_list_show, NULL);
+}
+
+static struct file_operations timer_list_fops = {
+       .open           = timer_list_open,
+       .read           = seq_read,
+       .llseek         = seq_lseek,
+       .release        = single_release,
+};
+
+static int __init init_timer_list_procfs(void)
+{
+       struct proc_dir_entry *pe;
+
+       pe = proc_create("timer_wheel_list", 0444, NULL, &timer_list_fops);
+       if (!pe)
+               return -ENOMEM;
+       return 0;
+}
+late_initcall(init_timer_list_procfs);
+
+#endif /* CONFIG_PROC_FS */
+
 /**
 * msleep - sleep safely even with waitqueue interruptions
 * @msecs: Time in milliseconds to sleep for
--

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Signature · 7 lines
Michael Kerrisk Linux man-pages maintainer;
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author
#6 lore raw

PATCH 1/1 Display active jiffie timers in /proc/timer_list

Add to /proc/timer_list a display of the active jiffie timers.

Tested on i386 and x86_64, with 'less /proc/timer_list' and through SysRq-Q.

Signed-off-by Joe Korty <[email protected]>
kernel/timer.c +83 -0
Index: 2.6.28-rc6/kernel/timer.c
===================================================================
@@ -36,6 +36,8 @@
 #include <linux/syscalls.h>
 #include <linux/delay.h>
 #include <linux/tick.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
 #include <linux/kallsyms.h>
 
 #include <asm/uaccess.h>

@@ -1568,6 +1570,87 @@
 	open_softirq(TIMER_SOFTIRQ, run_timer_softirq);
 }
 
+#if defined(CONFIG_PROC_FS) || defined(CONFIG_MAGIC_SYSRQ)
+
+/*
+ * This allows printing both to /proc/timer_list and
+ * to the console (on SysRq-Q):
+ */
+#define SEQ_printf(m, x...)			\
+ do {						\
+	if (m)					\
+		seq_printf(m, x);		\
+	else					\
+		printk(x);			\
+ } while (0)
+
+static void print_nearest_symbol(struct seq_file *m, void *symaddr)
+{
+	char symname[KSYM_NAME_LEN];
+
+	if (lookup_symbol_name((unsigned long)symaddr, symname) < 0)
+		SEQ_printf(m, "<%p>", symaddr);
+	else
+		SEQ_printf(m, "%s", symname);
+}
+
+static void print_single_jtimer(struct seq_file *m, struct timer_list *timer)
+{
+	unsigned long base_jiffies = tbase_get_base(timer->base)->timer_jiffies;
+#ifdef CONFIG_TIMER_STATS
+	char tmp[TASK_COMM_LEN + 1];
+#endif
+
+	SEQ_printf(m, " %p: ", (void *)(timer->expires - base_jiffies));
+	print_nearest_symbol(m, timer->function);
+	SEQ_printf(m, " (");
+	print_nearest_symbol(m, (void *)(timer->data));
+	SEQ_printf(m, ")");
+#ifdef CONFIG_TIMER_STATS
+	SEQ_printf(m, " from ");
+	print_nearest_symbol(m, timer->start_site);
+	memcpy(tmp, timer->start_comm, TASK_COMM_LEN);
+	tmp[TASK_COMM_LEN] = 0;
+	SEQ_printf(m, ", %s/%d", tmp, timer->start_pid);
+#endif
+	SEQ_printf(m, "\n");
+}
+
+static void print_list_jtimers(struct seq_file *m, struct list_head *head)
+{
+	struct timer_list *timer;
+	struct list_head *item;
+
+	for (item = head->next; item != head; item = item->next) {
+		timer = list_entry(item, struct timer_list, entry);
+		print_single_jtimer(m, timer);
+	}
+}
+
+void print_cpu_jtimers(struct seq_file *m, int cpu)
+{
+	int i;
+	struct tvec_base *base = per_cpu(tvec_bases, cpu);
+
+	SEQ_printf(m, "active jiffie timers:\n");
+	spin_lock_irq(&base->lock);
+	SEQ_printf(m, " base: %p\n", base);
+	SEQ_printf(m, " timer_jiffies: %p\n", (void *)(base->timer_jiffies));
+	SEQ_printf(m, " running_timer: %p\n", base->running_timer);
+
+	for (i = 0; i < TVR_SIZE; i++)
+		print_list_jtimers(m, base->tv1.vec + i);
+	for (i = 0; i < TVN_SIZE; i++) {
+		print_list_jtimers(m, base->tv2.vec + i);
+		print_list_jtimers(m, base->tv3.vec + i);
+		print_list_jtimers(m, base->tv4.vec + i);
+		print_list_jtimers(m, base->tv5.vec + i);
+	}
+	spin_unlock_irq(&base->lock);
+}
+
+#endif /* CONFIG_PROC_FS || CONFIG_MAGIC_SYSRQ */
+
 /**
  * msleep - sleep safely even with waitqueue interruptions
  * @msecs: Time in milliseconds to sleep for
include/linux/jiffies.h +7 -0
Index: 2.6.28-rc6/include/linux/jiffies.h
===================================================================
@@ -298,6 +298,13 @@
 extern u64 jiffies_64_to_clock_t(u64 x);
 extern u64 nsec_to_clock_t(u64 x);
 
+struct seq_file;
+#if defined(CONFIG_PROC_FS) || defined(CONFIG_MAGIC_SYSRQ)
+extern void print_cpu_jtimers(struct seq_file *, int);
+#else
+static inline void print_cpu_jtimers(struct seq_file *, int) {}
+#endif
+
 #define TIMESTAMP_SIZE	30
 
 #endif
kernel/time/timer_list.c +7 -3
Index: 2.6.28-rc6/kernel/time/timer_list.c
===================================================================
@@ -17,6 +17,7 @@
 #include <linux/seq_file.h>
 #include <linux/kallsyms.h>
 #include <linux/tick.h>
+#include <linux/jiffies.h>
 
 #include <asm/uaccess.h>
 

@@ -139,6 +140,7 @@
 		SEQ_printf(m, " clock %d:\n", i);
 		print_base(m, cpu_base->clock_base + i, now);
 	}
+
 #define P(x) \
 	SEQ_printf(m, "  .%-15s: %Lu\n", #x, \
 		   (unsigned long long)(cpu_base->x))

@@ -176,9 +178,11 @@
 		P(last_jiffies);
 		P(next_jiffies);
 		P_ns(idle_expires);
-		SEQ_printf(m, "jiffies: %Lu\n",
+		SEQ_printf(m, "jiffies: %llu (0x%llx)\n",
+			   (unsigned long long)jiffies,
 			   (unsigned long long)jiffies);
 	}
+	print_cpu_jtimers(m, cpu);
 #endif
 
 #undef P

@@ -252,7 +256,7 @@
 	u64 now = ktime_to_ns(ktime_get());
 	int cpu;
 
-	SEQ_printf(m, "Timer List Version: v0.4\n");
+	SEQ_printf(m, "Timer List Version: v0.5\n");
 	SEQ_printf(m, "HRTIMER_MAX_CLOCK_BASES: %d\n", HRTIMER_MAX_CLOCK_BASES);
 	SEQ_printf(m, "now at %Ld nsecs\n", (unsigned long long)now);
 

@@ -286,7 +290,7 @@
 {
 	struct proc_dir_entry *pe;
 
-	pe = proc_create("timer_list", 0644, NULL, &timer_list_fops);
+	pe = proc_create("timer_list", 0444, NULL, &timer_list_fops);
 	if (!pe)
 		return -ENOMEM;
 	return 0;
#7 lore raw

Re: [PATCH] Display active jiffie timers in /proc/timer_list

Joe,

Quoted 21 lines · Joe Korty

Add to /proc/timer_list a display of the active jiffie timers.

Tested on i386 and x86_64, with 'less /proc/timer_list' and through SysRq-Q.

Signed-off-by Joe Korty <[email protected]>

Index: 2.6.28-rc6/kernel/timer.c
===================================================================

kernel/timer.c +2 -0
@@ -36,6 +36,8 @@
 #include <linux/syscalls.h>
 #include <linux/delay.h>
 #include <linux/tick.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
 #include <linux/kallsyms.h>
 
 #include <asm/uaccess.h>

kernel/timer.c line 1573

Quoted 4 lines
kernel/timer.c +1 -0
@@ -1568,6 +1570,87 @@
 	open_softirq(TIMER_SOFTIRQ, run_timer_softirq);
 }
 
+#if defined(CONFIG_PROC_FS) || defined(CONFIG_MAGIC_SYSRQ)

This belongs into kernel/time/timer_list.c and there is no need to copy that code around.

kernel/timer.c line 1636

Quoted 7 lines
kernel/timer.c +7 -0
+void print_cpu_jtimers(struct seq_file *m, int cpu)
+{
+	int i;
+	struct tvec_base *base = per_cpu(tvec_bases, cpu);
+
+	SEQ_printf(m, "active jiffie timers:\n");
+	spin_lock_irq(&base->lock);

Yuck. We really do _NOT_ stop everything just to print timers. Check the hrtimer print code in timer_list.c

Quoted 13 lines

Index: 2.6.28-rc6/kernel/time/timer_list.c
===================================================================

kernel/time/timer_list.c +1 -0
@@ -17,6 +17,7 @@
 #include <linux/seq_file.h>
 #include <linux/kallsyms.h>
 #include <linux/tick.h>
+#include <linux/jiffies.h>
 
 #include <asm/uaccess.h>

kernel/time/timer_list.c line 143

Quoted 4 lines
kernel/time/timer_list.c +1 -0
@@ -139,6 +140,7 @@
 		SEQ_printf(m, " clock %d:\n", i);
 		print_base(m, cpu_base->clock_base + i, now);
 	}
+

random whitespace change

kernel/time/timer_list.c line 183

Quoted 11 lines
kernel/time/timer_list.c +2 -1
 #define P(x) \
 	SEQ_printf(m, "  .%-15s: %Lu\n", #x, \
 		   (unsigned long long)(cpu_base->x))

@@ -176,9 +178,11 @@
 		P(last_jiffies);
 		P(next_jiffies);
 		P_ns(idle_expires);
-		SEQ_printf(m, "jiffies: %Lu\n",
+		SEQ_printf(m, "jiffies: %llu (0x%llx)\n",
+			   (unsigned long long)jiffies,
 			   (unsigned long long)jiffies);

The exact purpose of this change ?

kernel/time/timer_list.c line 296

Quoted 9 lines
kernel/time/timer_list.c +1 -1
@@ -286,7 +290,7 @@
 {
 	struct proc_dir_entry *pe;
 
-	pe = proc_create("timer_list", 0644, NULL, &timer_list_fops);
+	pe = proc_create("timer_list", 0444, NULL, &timer_list_fops);
 	if (!pe)
 		return -ENOMEM;
 	return 0;

Correct, but unrelated $subject. Separate patch please.

Thanks,

tglx
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author
#8 lore raw

Re: [PATCH] Display active jiffie timers in /proc/timer_list

Quoted 6 lines · Thomas Gleixner

kernel/timer.c 2008-11-25 13:49:05.000000000 -0500

Quoted 3 lines
kernel/timer.c 2008-11-25 13:49:05.000000000 -0500 renamed from kernel/timer.c 2008-11-25 11:59:07.000000000 -0500 +1 -0
+#if defined(CONFIG_PROC_FS) || defined(CONFIG_MAGIC_SYSRQ)

This belongs into kernel/time/timer_list.c and there is no need to copy that code around.

Everything to do with jiffy timer implementation is static local to kernel/timer.c, and not available to code in kernel/time/timer_list.c or anywhere else. I consider that localization to be a rather nice feature of kernel/timer.c, and I wasn't willing to globalize it just for a debug data dump.

Also, other features implement their 'show' functions elsewhere, for example, show_interrupts. So doing the same thing here is certainly not out of line.

Quoted 10 lines

kernel/timer.c 2008-11-25 13:49:05.000000000 -0500

Quoted 7 lines
kernel/timer.c 2008-11-25 13:49:05.000000000 -0500 renamed from kernel/timer.c 2008-11-25 11:59:07.000000000 -0500 +7 -0
+void print_cpu_jtimers(struct seq_file *m, int cpu)
+{
+     int i;
+     struct tvec_base *base = per_cpu(tvec_bases, cpu);
+
+     SEQ_printf(m, "active jiffie timers:\n");
+     spin_lock_irq(&base->lock);

Yuck. We really do _NOT_ stop everything just to print timers. Check the hrtimer print code in timer_list.c

I'm not sure there is a safe way to reference the timers without holding the lock. But I will look into this and see what can be done.

Quoted 8 lines

kernel/timer.c 2008-11-25 13:49:05.000000000 -0500 line 143

Quoted 6 lines
kernel/timer.c 2008-11-25 13:49:05.000000000 -0500 renamed from kernel/timer.c 2008-11-25 11:59:07.000000000 -0500 +1 -0
@@ -139,6 +140,7 @@
              SEQ_printf(m, " clock %d:\n", i);
              print_base(m, cpu_base->clock_base + i, now);
      }
+

random whitespace change

Will fix.

Quoted 7 lines

kernel/timer.c 2008-11-25 13:49:05.000000000 -0500

Quoted 5 lines
kernel/timer.c 2008-11-25 13:49:05.000000000 -0500 renamed from kernel/timer.c 2008-11-25 11:59:07.000000000 -0500 +2 -1
              P_ns(idle_expires);
-             SEQ_printf(m, "jiffies: %Lu\n",
+             SEQ_printf(m, "jiffies: %llu (0x%llx)\n",
+                        (unsigned long long)jiffies,
                         (unsigned long long)jiffies);

The exact purpose of this change ?

In the 'active jiffie timer' section I print timer_jiffies etc in hex format. It's probably just me, but I found that to be easier to read than the rather longer decimal format. So this change was to get a hex version of the global jiffies out, for easy comparison to values appearing in that section.

Certainly everything can be changed to decimal, if that is the consensus.

Quoted 7 lines

kernel/timer.c 2008-11-25 13:49:05.000000000 -0500

Quoted 5 lines
kernel/timer.c 2008-11-25 13:49:05.000000000 -0500 renamed from kernel/timer.c 2008-11-25 11:59:07.000000000 -0500 +1 -1
-     pe = proc_create("timer_list", 0644, NULL, &timer_list_fops);
+     pe = proc_create("timer_list", 0444, NULL, &timer_list_fops);
      if (!pe)
              return -ENOMEM;
      return 0;

Correct, but unrelated $subject. Separate patch please.

Will do.

Thanks for the review,
Joe
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#9 lore raw

Re: [PATCH] Display active jiffie timers in /proc/timer_list

Quoted 15 lines · Joe Korty
Quoted 6 lines · Thomas Gleixner

kernel/timer.c 2008-11-25 13:49:05.000000000 -0500

Quoted 3 lines
kernel/timer.c 2008-11-25 13:49:05.000000000 -0500 renamed from kernel/timer.c 2008-11-25 11:59:07.000000000 -0500 +1 -0
+#if defined(CONFIG_PROC_FS) || defined(CONFIG_MAGIC_SYSRQ)

This belongs into kernel/time/timer_list.c and there is no need to copy that code around.

Everything to do with jiffy timer implementation is static local to kernel/timer.c, and not available to code in kernel/time/timer_list.c or anywhere else. I consider that localization to be a rather nice feature of kernel/timer.c, and I wasn't willing to globalize it just for a debug data dump.

Quoted 3 lines

Also, other features implement their 'show' functions elsewhere, for example, show_interrupts. So doing the same thing here is certainly not out of line.

I prefer a global variable over duplicate code and stuff which I have to find out from random places.

show_interrupts is arch specific. timers are not.

Quoted 11 lines
Quoted 10 lines

kernel/timer.c 2008-11-25 13:49:05.000000000 -0500

Quoted 7 lines
kernel/timer.c 2008-11-25 13:49:05.000000000 -0500 renamed from kernel/timer.c 2008-11-25 11:59:07.000000000 -0500 +7 -0
+void print_cpu_jtimers(struct seq_file *m, int cpu)
+{
+     int i;
+     struct tvec_base *base = per_cpu(tvec_bases, cpu);
+
+     SEQ_printf(m, "active jiffie timers:\n");
+     spin_lock_irq(&base->lock);

Yuck. We really do _NOT_ stop everything just to print timers. Check the hrtimer print code in timer_list.c

Quoted 3 lines

I'm not sure there is a safe way to reference the timers without holding the lock. But I will look into this and see what can be done.

You can't do a real snapshot of the timer wheel. All you can do is walk it carefully and make a copy of the timer_list structure and then print it. The timer wheel can be pretty full and we definitely do not want to stop a CPU fully just to print debug information.

Quoted 8 lines
Quoted 7 lines

kernel/timer.c 2008-11-25 13:49:05.000000000 -0500

Quoted 5 lines
              P_ns(idle_expires);
kernel/timer.c 2008-11-25 13:49:05.000000000 -0500 renamed from kernel/timer.c 2008-11-25 11:59:07.000000000 -0500 +2 -1
-             SEQ_printf(m, "jiffies: %Lu\n",
+             SEQ_printf(m, "jiffies: %llu (0x%llx)\n",
+                        (unsigned long long)jiffies,
                         (unsigned long long)jiffies);

The exact purpose of this change ?

Quoted 8 lines

In the 'active jiffie timer' section I print timer_jiffies etc in hex format. It's probably just me, but I found that to be easier to read than the rather longer decimal format. So this change was to get a hex version of the global jiffies out, for easy comparison to values appearing in that section.

Certainly everything can be changed to decimal, if that is the consensus.

We want a consistent format for all the printouts.

Thanks,

tglx

author
#10 lore raw

PATCH 1/1 Display active jiffie timers in /proc/timer_list, v2

In reply to Joe Korty

Add an 'active jiffie timers' subdisplay to /proc/timer_list, v2.

Version 1-to-2 features:
1) Version 1 created display code moved from kernel/timer.c to kernel/time/timer_list.c. To support this, kernel/timer.c internals were moved to a new header file, timer-internals.h, which is now included by both of the above .c files.

2) No longer locks a cpus' timer wheel for the entire duration of the printing of that wheel's timers; we now instead grab and release the lock on a per timer wheel slot basis. Refinements: we don't grab the lock at all for those slots which are obviously empty (which will be most of them most of the time), and we have pushed out the actual printing of the timers past the point where the lock is dropped.

3) Version 1 hex displays changed to decimal, to match the style of the other /proc/timer_list output.

Signed-off-by Joe Korty <[email protected]>
kernel/timer.c +3 -60
Index: 2.6.28-rc6/kernel/timer.c
===================================================================
@@ -44,73 +44,16 @@
 #include <asm/timex.h>
 #include <asm/io.h>
 
+#include <linux/timer-internals.h>
+
 u64 jiffies_64 __cacheline_aligned_in_smp = INITIAL_JIFFIES;
 
 EXPORT_SYMBOL(jiffies_64);
 
-/*
- * per-CPU timer vector definitions:
- */
-#define TVN_BITS (CONFIG_BASE_SMALL ? 4 : 6)
-#define TVR_BITS (CONFIG_BASE_SMALL ? 6 : 8)
-#define TVN_SIZE (1 << TVN_BITS)
-#define TVR_SIZE (1 << TVR_BITS)
-#define TVN_MASK (TVN_SIZE - 1)
-#define TVR_MASK (TVR_SIZE - 1)
-
-struct tvec {
-	struct list_head vec[TVN_SIZE];
-};
-
-struct tvec_root {
-	struct list_head vec[TVR_SIZE];
-};
-
-struct tvec_base {
-	spinlock_t lock;
-	struct timer_list *running_timer;
-	unsigned long timer_jiffies;
-	struct tvec_root tv1;
-	struct tvec tv2;
-	struct tvec tv3;
-	struct tvec tv4;
-	struct tvec tv5;
-} ____cacheline_aligned;
-
 struct tvec_base boot_tvec_bases;
 EXPORT_SYMBOL(boot_tvec_bases);
-static DEFINE_PER_CPU(struct tvec_base *, tvec_bases) = &boot_tvec_bases;
-
-/*
- * Note that all tvec_bases are 2 byte aligned and lower bit of
- * base in timer_list is guaranteed to be zero. Use the LSB for
- * the new flag to indicate whether the timer is deferrable
- */
-#define TBASE_DEFERRABLE_FLAG		(0x1)
+DEFINE_PER_CPU(struct tvec_base *, tvec_bases) = &boot_tvec_bases;
 
-/* Functions below help us manage 'deferrable' flag */
-static inline unsigned int tbase_get_deferrable(struct tvec_base *base)
-{
-	return ((unsigned int)(unsigned long)base & TBASE_DEFERRABLE_FLAG);
-}
-
-static inline struct tvec_base *tbase_get_base(struct tvec_base *base)
-{
-	return ((struct tvec_base *)((unsigned long)base & ~TBASE_DEFERRABLE_FLAG));
-}
-
-static inline void timer_set_deferrable(struct timer_list *timer)
-{
-	timer->base = ((struct tvec_base *)((unsigned long)(timer->base) |
-				       TBASE_DEFERRABLE_FLAG));
-}
-
-static inline void
-timer_set_base(struct timer_list *timer, struct tvec_base *new_base)
-{
-	timer->base = (struct tvec_base *)((unsigned long)(new_base) |
-				      tbase_get_deferrable(timer->base));
-}
 
 static unsigned long round_jiffies_common(unsigned long j, int cpu,
 		bool force_up)
kernel/time/timer_list.c +108 -1

133 lines not on this page · raw message

include/linux/timer-internals.h new file +67 -0

67 lines not on this page · raw message

#11 lore raw

Re: [PATCH] Display active jiffie timers in /proc/timer_list, v2

Quoted 1 line · Joe Korty

Add an 'active jiffie timers' subdisplay to /proc/timer_list, v2.

Can you add the documentation for this new field to Documentation/ABI/ as you are changing/adding a public API.

thanks,

greg k-h
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author
#12 lore raw

Re: [PATCH] Display active jiffie timers in /proc/timer_list, v2

Quoted 5 lines · Greg KH
Quoted 1 line · Joe Korty

Add an 'active jiffie timers' subdisplay to /proc/timer_list, v2.

Can you add the documentation for this new field to Documentation/ABI/ as you are changing/adding a public API.

OK.

Right now there is no ABI documention for anything in /proc/timer_list. Do you prefer one file for everything in /proc/timer_list, or a seperate file for each of the subsections?

I was also thinking the doc(s) should go into the /testing subsection, as the displayed revision number is < 1.0.

Joe
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#13 lore raw

Re: [PATCH] Display active jiffie timers in /proc/timer_list, v2

Quoted 4 lines · Joe Korty
Quoted 3 lines · Greg KH
Quoted 1 line · Joe Korty

Add an 'active jiffie timers' subdisplay to /proc/timer_list, v2.

Quoted 8 lines
Quoted 2 lines

Can you add the documentation for this new field to Documentation/ABI/ as you are changing/adding a public API.

OK.

Right now there is no ABI documention for anything in /proc/timer_list.

Yeah, you touched it last, so you get to document it all, sorry, it's not fair, but it's how we are slowly fixing these issues :)

Quoted 2 lines

Do you prefer one file for everything in /proc/timer_list, or a seperate file for each of the subsections?

Whatever you feel would be best is fine.

Quoted 2 lines

I was also thinking the doc(s) should go into the /testing subsection, as the displayed revision number is < 1.0.

Due to how long this has been in the kernel, I think it's fair to say it's part of the stable section now.

thanks,

greg k-h
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#14 lore raw

PATCH 1/1 ABI Documentation for /proc/timer_list

Document /proc/timer_list ABI.

This documents all of /timer_list, including the extension adding jiffie timers, as proposed in the patch:

[PATCH] Display active jiffie timers in /proc/timer_list, v2

Signed-off-by Joe Korty <[email protected]>
Documentation/ABI/stable/procfs-timer_list new file +96 -0
Index: 2.6.28-rc6/Documentation/ABI/stable/procfs-timer_list
===================================================================
@@ -0,0 +1,96 @@
+What:		/proc/timer_list
+Date:		November 2008
+Contact:	Ingo Molnar <[email protected]>
+		Thomas Gleixner <[email protected]>
+		Joe Korty <[email protected]>
+Revision-Rate:	Moderate
+At-Revision:	0.5
+Description:
+		/proc/timer_list displays most everything about every kind
+		of timer, and some things about time too.
+
+		The contents of this file should be expected to change,
+		as the data displayed corresponds directly to various
+		kernel-internal data structures.  For this reason, the first
+		line contains the file revision.  It is the responsibility
+		of this file's maintainers to bump the revision each time a
+		kernel is released having incompatible changes in this file.
+
+		Section Overview
+		----------------
+		The file contains several somewhat independent sections.
+
+		The first section contains a few lines of global info.
+		Examples: file version id, #clock types in the kernel,
+		#nsecs since boot.
+
+		The second section is organized per-cpu.  Each cpu subsection
+		in turn contains several sub-subsections which are, in order
+		of appearance:
+
+		   The contents of the data structures associated with each
+		   clock (CLOCK_REALTIME, CLOCK_MONOTONIC, etc) on this cpu.
+		   Examples: base, index, resolution, get_timer, offset.
+		   Under each of these clocks is, in turn, a display of all
+		   the active high resolution timers queued to that clock.
+		   Example: all lines beginning with '#'.
+
+		   The contents of per-cpu timer data fields not associated
+		   with a particular clock type (ie, shared by both clocks or
+		   not associated with any clock). Examples: expires_next,
+		   hres_active, nr_event, nohz_mode, all things idle_*,
+		   tick_stopped, last_jiffies, next_jiffies.
+
+		   A display of low resolution (ie, jiffie) timer wheel
+		   data.  Examples: base, running_timer, timer_jiffies.
+		   Also under this section is a display, one per line, of
+		   each active jiffie timer queued to this cpu.  Examples:
+		   All lines under an 'active jiffie timers' section that
+		   begin with a number.
+
+		The third and final section describes each 'tick device'
+		known to the kernel.  A tick device is a piece of hardware
+		capable of generating periodic and/or one shot interrupts
+		under software control, and thus is capable of generating
+		the interrupts needed to expire the various active timers at
+		their given expiration times.  Examples: hpet, pit, lapic.
+
+		Hires Timer Layout
+		------------------
+		High resolution timers are displayed on lines that begin
+		with a '#' and always appear under one of the many sections
+		labeled 'active timers'.  There is an 'active timers'
+		section for every cpu and every clock.
+
+		The fields of a hrtimer, spread out over two lines, are:
+
+		line 1 fields:
+		  1 - unique hrtimer index (#0, #1, #2, etc)
+		  2 - kernel address of the hrtimer data structure
+		      in question
+		  3 - function to be called when timer expires
+		  4 - timer state (eg, S:01), avail states, OR-able:
+		      0 - inactive
+		      1 - enqueued
+		      2 - callback
+		      4 - pending
+		      8 - migrate
+		  5 - function which created the timer
+		  6 - process name & pid which created the timer
+
+		line 2 fields:
+		  1 - absolute expiration time, range format (start - end)
+		  2 - relative expiration time, range format (start - end)
+
+		Lowres Timer Layout
+		-------------------
+		Low resolution timers are displayed one-per-line under
+		sections labeled 'active jiffie timers'.  There is one such
+		section per cpu.  A lowres timer has the following fields:
+
+		  1 - #jiffies remaining until timer expires
+		  2 - function to be called on expiration
+		  3 - data value to be given to the above function on
+		      expiration
+		  4 - function which created this timer
+		  5 - name & pid of the process that created this timer

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#15 lore raw

Re: [PATCH] ABI Documentation for /proc/timer_list

Joe,

Some comments and suggestions below.

Quoted 21 lines · Joe Korty

Document /proc/timer_list ABI.

This documents all of /timer_list, including the extension adding jiffie timers, as proposed in the patch:

[PATCH] Display active jiffie timers in /proc/timer_list, v2

Signed-off-by Joe Korty <[email protected]>

Index: 2.6.28-rc6/Documentation/ABI/stable/procfs-timer_list
===================================================================

Documentation/ABI/stable/procfs-timer_list 2008-11-26 15:55:04.000000000 -0500 renamed from dev/null 1970-01-01 00:00:00.000000000 +0000 +7 -0
@@ -0,0 +1,96 @@
+What:          /proc/timer_list
+Date:          November 2008
+Contact:       Ingo Molnar <[email protected]>
+               Thomas Gleixner <[email protected]>
+               Joe Korty <[email protected]>
+Revision-Rate: Moderate
+At-Revision:   0.5

Documentation/ABI/stable/procfs-timer_list 2008-11-26 15:55:04.000000000 -0500 line 17

Quoted 10 lines
Documentation/ABI/stable/procfs-timer_list 2008-11-26 15:55:04.000000000 -0500 renamed from dev/null 1970-01-01 00:00:00.000000000 +0000 +10 -0
+Description:
+               /proc/timer_list displays most everything about every kind
+               of timer, and some things about time too.
+
+               The contents of this file should be expected to change,
+               as the data displayed corresponds directly to various
+               kernel-internal data structures.  For this reason, the first
+               line contains the file revision.  It is the responsibility
+               of this file's maintainers to bump the revision each time a
+               kernel is released having incompatible changes in this file.

So, on my 2.6.25 system, I see v0.3. And I see that by 2.6.28-rc, we have v0.4. It would be nice to have some explanation here of what the x.y version number means in this context.

And where are the differences between versions (e.g., 0.3 and 0.4) documented?

Documentation/ABI/stable/procfs-timer_list 2008-11-26 15:55:04.000000000 -0500 line 23

Quoted 6 lines
Documentation/ABI/stable/procfs-timer_list 2008-11-26 15:55:04.000000000 -0500 renamed from dev/null 1970-01-01 00:00:00.000000000 +0000 +6 -0
+               Section Overview
+               ----------------
+               The file contains several somewhat independent sections.
+
+               The first section contains a few lines of global info.
+               Examples: file version id, #clock types in the kernel,

IMO, it really helps readers when documentation is written in something like natural language. "#clock types" may save you a few moments of time, but "number of clock types" will probably be clearer to yout (hopefully many) readers.

But: what does "clock types" refer to? The HRTIMER_MAX_CLOCK_BASES line? If so, that's not obvious from this description.

Documentation/ABI/stable/procfs-timer_list 2008-11-26 15:55:04.000000000 -0500 line 24

Quoted 1 line
Documentation/ABI/stable/procfs-timer_list 2008-11-26 15:55:04.000000000 -0500 renamed from dev/null 1970-01-01 00:00:00.000000000 +0000 +1 -0
+               #nsecs since boot.

See previous comment.

Documentation/ABI/stable/procfs-timer_list 2008-11-26 15:55:04.000000000 -0500 line 26

Quoted 2 lines
Documentation/ABI/stable/procfs-timer_list 2008-11-26 15:55:04.000000000 -0500 renamed from dev/null 1970-01-01 00:00:00.000000000 +0000 +2 -0
+
+               The second section is organized per-cpu.  Each cpu subsection

1,$s/cpu/CPU/g

Documentation/ABI/stable/procfs-timer_list 2008-11-26 15:55:04.000000000 -0500 line 31

Quoted 5 lines
Documentation/ABI/stable/procfs-timer_list 2008-11-26 15:55:04.000000000 -0500 renamed from dev/null 1970-01-01 00:00:00.000000000 +0000 +5 -0
+               in turn contains several sub-subsections which are, in order
+               of appearance:
+
+                  The contents of the data structures associated with each
+                  clock (CLOCK_REALTIME, CLOCK_MONOTONIC, etc) on this cpu.

(How) can I work out whether clock 0 is CLOCK_REALTIME, etc?

Documentation/ABI/stable/procfs-timer_list 2008-11-26 15:55:04.000000000 -0500 line 32

Quoted 1 line
Documentation/ABI/stable/procfs-timer_list 2008-11-26 15:55:04.000000000 -0500 renamed from dev/null 1970-01-01 00:00:00.000000000 +0000 +1 -0
+                  Examples: base, index, resolution, get_timer, offset.

Ahh -- base looks like one of the changes between v0.3 and v0.4... Would be nice to let the reader know this, perhaps?

Also, how about adding a line on what each of these fields represents.

Documentation/ABI/stable/procfs-timer_list 2008-11-26 15:55:04.000000000 -0500 line 41

Quoted 9 lines
Documentation/ABI/stable/procfs-timer_list 2008-11-26 15:55:04.000000000 -0500 renamed from dev/null 1970-01-01 00:00:00.000000000 +0000 +9 -0
+                  Under each of these clocks is, in turn, a display of all
+                  the active high resolution timers queued to that clock.
+                  Example: all lines beginning with '#'.
+
+                  The contents of per-cpu timer data fields not associated
+                  with a particular clock type (ie, shared by both clocks or
+                  not associated with any clock). Examples: expires_next,
+                  hres_active, nr_event, nohz_mode, all things idle_*,
+                  tick_stopped, last_jiffies, next_jiffies.

How about adding a line on what each of these fields represents.

Documentation/ABI/stable/procfs-timer_list 2008-11-26 15:55:04.000000000 -0500 line 44

Quoted 3 lines
Documentation/ABI/stable/procfs-timer_list 2008-11-26 15:55:04.000000000 -0500 renamed from dev/null 1970-01-01 00:00:00.000000000 +0000 +3 -0
+
+                  A display of low resolution (ie, jiffie) timer wheel
+                  data.  Examples: base, running_timer, timer_jiffies.

At the risk of sounding repetitive... How about adding a line on what each of these fields represents.

Documentation/ABI/stable/procfs-timer_list 2008-11-26 15:55:04.000000000 -0500 line 52

Quoted 8 lines
Documentation/ABI/stable/procfs-timer_list 2008-11-26 15:55:04.000000000 -0500 renamed from dev/null 1970-01-01 00:00:00.000000000 +0000 +8 -0
+                  Also under this section is a display, one per line, of
+                  each active jiffie timer queued to this cpu.  Examples:
+                  All lines under an 'active jiffie timers' section that
+                  begin with a number.
+
+               The third and final section describes each 'tick device'
+               known to the kernel.  A tick device is a piece of hardware
+               capable of generating periodic and/or one shot interrupts

s/one shot/one-shot/

Documentation/ABI/stable/procfs-timer_list 2008-11-26 15:55:04.000000000 -0500 line 59

Quoted 7 lines
Documentation/ABI/stable/procfs-timer_list 2008-11-26 15:55:04.000000000 -0500 renamed from dev/null 1970-01-01 00:00:00.000000000 +0000 +7 -0
+               under software control, and thus is capable of generating
+               the interrupts needed to expire the various active timers at
+               their given expiration times.  Examples: hpet, pit, lapic.
+
+               Hires Timer Layout
+               ------------------
+               High resolution timers are displayed on lines that begin

s/High resolution/High-resolution/

Quoted 17 lines
Documentation/ABI/stable/procfs-timer_list 2008-11-26 15:55:04.000000000 -0500 renamed from dev/null 1970-01-01 00:00:00.000000000 +0000 +17 -0
+               with a '#' and always appear under one of the many sections
+               labeled 'active timers'.  There is an 'active timers'
+               section for every cpu and every clock.
+
+               The fields of a hrtimer, spread out over two lines, are:
+
+               line 1 fields:
+                 1 - unique hrtimer index (#0, #1, #2, etc)
+                 2 - kernel address of the hrtimer data structure
+                     in question
+                 3 - function to be called when timer expires
+                 4 - timer state (eg, S:01), avail states, OR-able:
+                     0 - inactive
+                     1 - enqueued
+                     2 - callback
+                     4 - pending
+                     8 - migrate

Documentation/ABI/stable/procfs-timer_list 2008-11-26 15:55:04.000000000 -0500 line 86

Quoted 10 lines
Documentation/ABI/stable/procfs-timer_list 2008-11-26 15:55:04.000000000 -0500 renamed from dev/null 1970-01-01 00:00:00.000000000 +0000 +10 -0
+                 5 - function which created the timer
+                 6 - process name & pid which created the timer
+
+               line 2 fields:
+                 1 - absolute expiration time, range format (start - end)
+                 2 - relative expiration time, range format (start - end)
+
+               Lowres Timer Layout
+               -------------------
+               Low resolution timers are displayed one-per-line under

s/Low resolution/Low-resolution/

Documentation/ABI/stable/procfs-timer_list 2008-11-26 15:55:04.000000000 -0500 line 95

Quoted 9 lines
Documentation/ABI/stable/procfs-timer_list 2008-11-26 15:55:04.000000000 -0500 renamed from dev/null 1970-01-01 00:00:00.000000000 +0000 +9 -0
+               sections labeled 'active jiffie timers'.  There is one such
+               section per cpu.  A lowres timer has the following fields:
+
+                 1 - #jiffies remaining until timer expires
+                 2 - function to be called on expiration
+                 3 - data value to be given to the above function on
+                     expiration
+                 4 - function which created this timer
+                 5 - name & pid of the process that created this timer

Cheers,

Michael

Signature · 9 lines
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
git://git.kernel.org/pub/scm/docs/man-pages/man-pages.git
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Found a bug? http://www.kernel.org/doc/man-pages/reporting_bugs.html
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author
#16 lore raw

PATCH 1/1 ABI Documentation for /proc/timer_list, v2

Document /proc/timer_list ABI, version 2.

This partially documents /timer_list, including the proposed 'Version 0.5' extensions that add a jiffie timer display.

v2 exists to address some of the concerns Michael Kerrisk brought up. What was left out: I did not document old versions of /timer_list, I did not document the meaning of the x.y version numbering system (which only Ingo can answer anyway), and I did not document fields of secondary importance that already had adequate 'DocBook' documentation in the kernel sources.

Signed-off-by Joe Korty <[email protected]>
Documentation/ABI/stable/procfs-timer_list new file +129 -0
Index: 2.6.28-rc6/Documentation/ABI/stable/procfs-timer_list
===================================================================
@@ -0,0 +1,129 @@
+What:		/proc/timer_list
+Date:		November 2008
+Contact:	Ingo Molnar <[email protected]>
+		Thomas Gleixner <[email protected]>
+		Joe Korty <[email protected]>
+Revision-Rate:	Moderate
+At-Revision:	0.5
+Description:
+		/proc/timer_list displays most everything about every kind
+		of timer, and some things about time too.
+
+		The contents of this file should be expected to change,
+		as the data displayed corresponds directly to various
+		kernel-internal data structures.  For this reason, the first
+		line contains the file revision.  It is the responsibility
+		of this file's maintainers to bump the revision each time a
+		kernel is released having incompatible changes in this file.
+
+		This document covers only the version of /proc/timer_list
+		located in the kernel sources to which it is attached.
+		Documentation for previous (and later) versions of
+		/proc/timer_list is to be found (if they exist) in the
+		kernel sources of those earlier (or later) kernels.
+
+		Section Overview
+		----------------
+		The file contains several somewhat independent sections.
+
+		The first section contains a few lines of global info:
+		   1 - Timer List Version: File revision.
+		   2 - HRTIMER_MAX_CLOCK_BASES: number of clock types that
+		       support high resolution timers.
+		   3 - now at x nsecs: number of nsecs since boot.
+
+		The second section is organized per-CPU.  Each CPU subsection
+		in turn contains several sub-subsections which are, in order
+		of appearance:
+
+		   The contents of the data structures associated with each
+		   clock on this CPU:
+		    1 - clock ID: 0 == CLOCK_REALTIME, 1 == CLOCK_MONOTONIC
+		    2 - base: kernel address of this clock's
+		        hrtimer_clock_base structure.
+		    3 - resolution: resolution of this clock.
+		    4 - get_time: name of kernel function used to fetch
+		        time from this clock.
+		    5 - offset: difference, in nsecs, between this clock
+		        and the reference clock for this clock.
+		   Under each of these clocks is, in turn, a display of all
+		   the active high resolution timers queued to that clock.
+		   These are the lines beginning with '#' and are described
+		   in detail later in this document.
+
+		   The contents of per-CPU hrtimer data fields not
+		   associated with a particular cpu clock (ie, shared by
+		   both clocks or not associated with any clock).  These
+		   are: expires_next, hres_active, nr_event, nohz_mode, all
+		   things idle_*, tick_stopped, last_jiffies, next_jiffies.
+		   The above are field names from 'struct tick_sched' and
+		   'struct hrtimer_cpu_base', documentation for these may
+		   be found in the kernel DocBook.
+
+		   A display of low resolution (ie, jiffie) timer wheel
+		   data.  These are prefixed by the lines:
+		    1 - base: kernel virtual address of the timer wheel
+		        data structure (struct tvec_base) for this cpu.
+		    2 - running timer: kernel virtual address of the
+		        expired timer being processed, NULL if none.
+		    3 - timer_jiffies: what this wheel considers to
+		        be the current time, will be == jiffies or
+			will lag it by a tick or two if it has not
+			caught up with the current time.
+		   Also under this section is a display, one per line, of
+		   each active jiffie timer queued to this CPU.  These are
+		   the lines under an 'active jiffie timers' section that
+		   begin with a number.
+
+		The third and final section describes each 'tick device'
+		known to the kernel.  A tick device is a piece of hardware
+		capable of generating periodic and/or one-shot interrupts
+		under software control, and thus is capable of generating
+		the interrupts needed to expire the various active timers
+		at their given expiration times.  Examples of tick devices:
+		hpet, pit, lapic.  All but the first two lines display
+		fields corresponding to structure elements from 'struct
+		clock_event_device', documentation for which can be found
+		in the kernel Docbook. The first two lines are:
+		  1 - mode: 0 == periodic timer, 1 == one-shot timer
+		  2 - is 'Per CPU device' or is 'Broadcast device'
+
+		Hires Timer Layout
+		------------------
+		High-resolution timers are displayed on lines that begin
+		with a '#' and always appear under one of the many sections
+		labeled 'active timers'.  There is an 'active timers'
+		section for every CPU and every clock.
+
+		The fields of a hrtimer, spread out over two lines, are:
+
+		line 1 fields:
+		  1 - unique hrtimer index (#0, #1, #2, etc)
+		  2 - kernel address of the hrtimer data structure
+		      in question
+		  3 - function to be called when timer expires
+		  4 - timer state (eg, S:01), avail states, OR-able:
+		      0 - inactive
+		      1 - enqueued
+		      2 - callback
+		      4 - pending
+		      8 - migrate
+		  5 - function which created the timer
+		  6 - process name & pid which created the timer
+
+		line 2 fields:
+		  1 - absolute expiration time, range format (start - end)
+		  2 - relative expiration time, range format (start - end)
+
+		Lowres Timer Layout
+		-------------------
+		Low-resolution timers are displayed one-per-line under
+		sections labeled 'active jiffie timers'.  There is one such
+		section per CPU.  A lowres timer has the following fields:
+
+		  1 - number of jiffies remaining until timer expires
+		  2 - function to be called on expiration
+		  3 - data value to be given to the above function on
+		      expiration
+		  4 - function which created this timer
+		  5 - name & pid of the process that created this timer

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#17 lore raw

Re: [PATCH] ABI Documentation for /proc/timer_list, v2

Quoted 63 lines · Joe Korty

Document /proc/timer_list ABI, version 2.

This partially documents /timer_list, including the proposed 'Version 0.5' extensions that add a jiffie timer display.

v2 exists to address some of the concerns Michael Kerrisk brought up. What was left out: I did not document old versions of /timer_list, I did not document the meaning of the x.y version numbering system (which only Ingo can answer anyway), and I did not document fields of secondary importance that already had adequate 'DocBook' documentation in the kernel sources.

Signed-off-by Joe Korty <[email protected]>

Index: 2.6.28-rc6/Documentation/ABI/stable/procfs-timer_list
===================================================================

Documentation/ABI/stable/procfs-timer_list new file +42 -0
@@ -0,0 +1,129 @@
+What:		/proc/timer_list
+Date:		November 2008
+Contact:	Ingo Molnar <[email protected]>
+		Thomas Gleixner <[email protected]>
+		Joe Korty <[email protected]>
+Revision-Rate:	Moderate
+At-Revision:	0.5
+Description:
+		/proc/timer_list displays most everything about every kind
+		of timer, and some things about time too.
+
+		The contents of this file should be expected to change,
+		as the data displayed corresponds directly to various
+		kernel-internal data structures.  For this reason, the first
+		line contains the file revision.  It is the responsibility
+		of this file's maintainers to bump the revision each time a
+		kernel is released having incompatible changes in this file.
+
+		This document covers only the version of /proc/timer_list
+		located in the kernel sources to which it is attached.
+		Documentation for previous (and later) versions of
+		/proc/timer_list is to be found (if they exist) in the
+		kernel sources of those earlier (or later) kernels.
+
+		Section Overview
+		----------------
+		The file contains several somewhat independent sections.
+
+		The first section contains a few lines of global info:
+		   1 - Timer List Version: File revision.
+		   2 - HRTIMER_MAX_CLOCK_BASES: number of clock types that
+		       support high resolution timers.
+		   3 - now at x nsecs: number of nsecs since boot.
+
+		The second section is organized per-CPU.  Each CPU subsection
+		in turn contains several sub-subsections which are, in order
+		of appearance:
+
+		   The contents of the data structures associated with each
+		   clock on this CPU:
+		    1 - clock ID: 0 == CLOCK_REALTIME, 1 == CLOCK_MONOTONIC
+		    2 - base: kernel address of this clock's

Documentation/ABI/stable/procfs-timer_list line 52

Quoted 10 lines
Documentation/ABI/stable/procfs-timer_list new file +10 -0
+		        hrtimer_clock_base structure.
+		    3 - resolution: resolution of this clock.
+		    4 - get_time: name of kernel function used to fetch
+		        time from this clock.
+		    5 - offset: difference, in nsecs, between this clock
+		        and the reference clock for this clock.
+		   Under each of these clocks is, in turn, a display of all
+		   the active high resolution timers queued to that clock.
+		   These are the lines beginning with '#' and are described
+		   in detail later in this document.

Are we supposed to be able to see lines beginning with '#' in this text file, or only in /proc/timer_list ?

Documentation/ABI/stable/procfs-timer_list line 55

Quoted 3 lines
Documentation/ABI/stable/procfs-timer_list new file +3 -0
+
+		   The contents of per-CPU hrtimer data fields not
+		   associated with a particular cpu clock (ie, shared by

Please use "CPU" consistenly (instead of "cpu").

Documentation/ABI/stable/procfs-timer_list line 60

Quoted 5 lines
Documentation/ABI/stable/procfs-timer_list new file +5 -0
+		   both clocks or not associated with any clock).  These
+		   are: expires_next, hres_active, nr_event, nohz_mode, all
+		   things idle_*, tick_stopped, last_jiffies, next_jiffies.
+		   The above are field names from 'struct tick_sched' and
+		   'struct hrtimer_cpu_base', documentation for these may

'struct hrtimer_cpu_base'; documentation for these may

Quoted 28 lines
Documentation/ABI/stable/procfs-timer_list new file +28 -0
+		   be found in the kernel DocBook.
+
+		   A display of low resolution (ie, jiffie) timer wheel
+		   data.  These are prefixed by the lines:
+		    1 - base: kernel virtual address of the timer wheel
+		        data structure (struct tvec_base) for this cpu.
+		    2 - running timer: kernel virtual address of the
+		        expired timer being processed, NULL if none.
+		    3 - timer_jiffies: what this wheel considers to
+		        be the current time, will be == jiffies or
+			will lag it by a tick or two if it has not
+			caught up with the current time.
+		   Also under this section is a display, one per line, of
+		   each active jiffie timer queued to this CPU.  These are
+		   the lines under an 'active jiffie timers' section that
+		   begin with a number.
+
+		The third and final section describes each 'tick device'
+		known to the kernel.  A tick device is a piece of hardware
+		capable of generating periodic and/or one-shot interrupts
+		under software control, and thus is capable of generating
+		the interrupts needed to expire the various active timers
+		at their given expiration times.  Examples of tick devices:
+		hpet, pit, lapic.  All but the first two lines display
+		fields corresponding to structure elements from 'struct
+		clock_event_device', documentation for which can be found
+		in the kernel Docbook. The first two lines are:
+		  1 - mode: 0 == periodic timer, 1 == one-shot timer

Documentation/ABI/stable/procfs-timer_list line 98

Quoted 10 lines
Documentation/ABI/stable/procfs-timer_list new file +10 -0
+		  2 - is 'Per CPU device' or is 'Broadcast device'
+
+		Hires Timer Layout
+		------------------
+		High-resolution timers are displayed on lines that begin
+		with a '#' and always appear under one of the many sections
+		labeled 'active timers'.  There is an 'active timers'
+		section for every CPU and every clock.
+
+		The fields of a hrtimer, spread out over two lines, are:

an hrtimer,

Quoted 21 lines
Documentation/ABI/stable/procfs-timer_list new file +21 -0
+
+		line 1 fields:
+		  1 - unique hrtimer index (#0, #1, #2, etc)
+		  2 - kernel address of the hrtimer data structure
+		      in question
+		  3 - function to be called when timer expires
+		  4 - timer state (eg, S:01), avail states, OR-able:
+		      0 - inactive
+		      1 - enqueued
+		      2 - callback
+		      4 - pending
+		      8 - migrate
+		  5 - function which created the timer
+		  6 - process name & pid which created the timer
+
+		line 2 fields:
+		  1 - absolute expiration time, range format (start - end)
+		  2 - relative expiration time, range format (start - end)
+
+		Lowres Timer Layout
+		-------------------

Documentation/ABI/stable/procfs-timer_list line 129

Quoted 10 lines
Documentation/ABI/stable/procfs-timer_list new file +10 -0
+		Low-resolution timers are displayed one-per-line under
+		sections labeled 'active jiffie timers'.  There is one such
+		section per CPU.  A lowres timer has the following fields:
+
+		  1 - number of jiffies remaining until timer expires
+		  2 - function to be called on expiration
+		  3 - data value to be given to the above function on
+		      expiration
+		  4 - function which created this timer
+		  5 - name & pid of the process that created this timer

Thanks,
~Randy

author
#18 lore raw

Re: [PATCH] ABI Documentation for /proc/timer_list, v2

Hi Randy,
Thanks for taking the time to review this. I get the impression, though, that the corresponding patch that creates the 0.5 version of /proc/timer_list is not going to be accepted. Perhaps I should strip down this ABI patch to document just the existing 0.4 /proc/timer_list.

Regards,
Joe

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