Commit f65c64f3 authored by Wang Yaxin's avatar Wang Yaxin Committed by Andrew Morton
Browse files

delayacct: add delay min to record delay peak 

Delay accounting can now calculate the average delay of processes, detect
the overall system load, and also record the 'delay max' to identify
potential abnormal delays.  However, 'delay min' can help us identify
another useful delay peak.  By comparing the difference between 'delay
max' and 'delay min', we can understand the optimization space for
latency, providing a reference for the optimization of latency
performance.

Use case
=========
bash-4.4# ./getdelays -d -t 242
print delayacct stats ON
TGID    242
CPU         count     real total  virtual total    delay total  delay average      delay max      delay min
               39      156000000      156576579        2111069          0.054ms     0.212296ms     0.031307ms
IO          count    delay total  delay average      delay max      delay min
                0              0          0.000ms     0.000000ms     0.000000ms
SWAP        count    delay total  delay average      delay max      delay min
                0              0          0.000ms     0.000000ms     0.000000ms
RECLAIM     count    delay total  delay average      delay max      delay min
                0              0          0.000ms     0.000000ms     0.000000ms
THRASHING   count    delay total  delay average      delay max      delay min
                0              0          0.000ms     0.000000ms     0.000000ms
COMPACT     count    delay total  delay average      delay max      delay min
                0              0          0.000ms     0.000000ms     0.000000ms
WPCOPY      count    delay total  delay average      delay max      delay min
              156       11215873          0.072ms     0.207403ms     0.033913ms
IRQ         count    delay total  delay average      delay max      delay min
                0              0          0.000ms     0.000000ms     0.000000ms

Link: https://lkml.kernel.org/r/20241220173105906EOdsPhzjMLYNJJBqgz1ga@zte.com.cn


Co-developed-by: default avatarWang Yong <wang.yong12@zte.com.cn>
Signed-off-by: default avatarWang Yong <wang.yong12@zte.com.cn>
Co-developed-by: default avatarxu xin <xu.xin16@zte.com.cn>
Signed-off-by: default avatarxu xin <xu.xin16@zte.com.cn>
Signed-off-by: default avatarWang Yaxin <wang.yaxin@zte.com.cn>
Co-developed-by: default avatarKun Jiang <jiang.kun2@zte.com.cn>
Signed-off-by: default avatarKun Jiang <jiang.kun2@zte.com.cn>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Fan Yu <fan.yu9@zte.com.cn>
Cc: Peilin He <he.peilin@zte.com.cn>
Cc: tuqiang <tu.qiang35@zte.com.cn>
Cc: ye xingchen <ye.xingchen@zte.com.cn>
Cc: Yunkai Zhang <zhang.yunkai@zte.com.cn>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 7e70433c

Documentation/accounting/delay-accounting.rst

+16 −16
Original line number Diff line number Diff line
@@ -107,22 +107,22 @@ Get sum and peak of delays, since system boot, for all pids with tgid 242:: 
	TGID    242





	CPU         count     real total  virtual total    delay total  delay average      delay max

	              239      296000000      307724885        1127792          0.005ms     0.238382ms

	IO          count    delay total  delay average      delay max

	                0              0          0.000ms     0.000000ms

	SWAP        count    delay total  delay average      delay max

	                0              0          0.000ms     0.000000ms

	RECLAIM     count    delay total  delay average      delay max

	                0              0          0.000ms     0.000000ms

	THRASHING   count    delay total  delay average      delay max

	                0              0          0.000ms     0.000000ms

	COMPACT     count    delay total  delay average      delay max

	                0              0          0.000ms     0.000000ms

	WPCOPY      count    delay total  delay average      delay max

	              230       19100476          0.083ms     0.383822ms

	IRQ         count    delay total  delay average      delay max

	                0              0          0.000ms     0.000000ms

	CPU         count     real total  virtual total    delay total  delay average      delay max      delay min

	               39      156000000      156576579        2111069          0.054ms     0.212296ms     0.031307ms

	IO          count    delay total  delay average      delay max      delay min

	                0              0          0.000ms     0.000000ms     0.000000ms

	SWAP        count    delay total  delay average      delay max      delay min

	                0              0          0.000ms     0.000000ms     0.000000ms

	RECLAIM     count    delay total  delay average      delay max      delay min

	                0              0          0.000ms     0.000000ms     0.000000ms

	THRASHING   count    delay total  delay average      delay max      delay min

	                0              0          0.000ms     0.000000ms     0.000000ms

	COMPACT     count    delay total  delay average      delay max      delay min

	                0              0          0.000ms     0.000000ms     0.000000ms

	WPCOPY      count    delay total  delay average      delay max      delay min

	              156       11215873          0.072ms     0.207403ms     0.033913ms

	IRQ         count    delay total  delay average      delay max      delay min

	                0              0          0.000ms     0.000000ms     0.000000ms



Get IO accounting for pid 1, it works only with -p::

include/linux/delayacct.h

+7 −0
Original line number Diff line number Diff line
@@ -30,9 +30,11 @@ struct task_delay_info { 
	 */

	u64 blkio_start;

	u64 blkio_delay_max;

	u64 blkio_delay_min;

	u64 blkio_delay;	/* wait for sync block io completion */

	u64 swapin_start;

	u64 swapin_delay_max;

	u64 swapin_delay_min;

	u64 swapin_delay;	/* wait for swapin */

	u32 blkio_count;	/* total count of the number of sync block */

				/* io operations performed */
@@ -40,21 +42,26 @@ struct task_delay_info { 


	u64 freepages_start;

	u64 freepages_delay_max;

	u64 freepages_delay_min;

	u64 freepages_delay;	/* wait for memory reclaim */



	u64 thrashing_start;

	u64 thrashing_delay_max;

	u64 thrashing_delay_min;

	u64 thrashing_delay;	/* wait for thrashing page */



	u64 compact_start;

	u64 compact_delay_max;

	u64 compact_delay_min;

	u64 compact_delay;	/* wait for memory compact */



	u64 wpcopy_start;

	u64 wpcopy_delay_max;

	u64 wpcopy_delay_min;

	u64 wpcopy_delay;	/* wait for write-protect copy */



	u64 irq_delay_max;

	u64 irq_delay_min;

	u64 irq_delay;	/* wait for IRQ/SOFTIRQ */



	u32 freepages_count;	/* total count of memory reclaim */

include/linux/sched.h

+3 −0
Original line number Diff line number Diff line
@@ -401,6 +401,9 @@ struct sched_info { 
	/* Max time spent waiting on a runqueue: */

	unsigned long long		max_run_delay;



	/* Min time spent waiting on a runqueue: */

	unsigned long long		min_run_delay;



	/* Timestamps: */



	/* When did we last run on a CPU? */

include/uapi/linux/taskstats.h

+8 −0
Original line number Diff line number Diff line
@@ -73,6 +73,7 @@ struct taskstats { 
	__u64	cpu_count __attribute__((aligned(8)));

	__u64	cpu_delay_total;

	__u64	cpu_delay_max;

	__u64	cpu_delay_min;



	/* Following four fields atomically updated using task->delays->lock */
@@ -82,11 +83,13 @@ struct taskstats { 
	__u64	blkio_count;

	__u64	blkio_delay_total;

	__u64	blkio_delay_max;

	__u64	blkio_delay_min;



	/* Delay waiting for page fault I/O (swap in only) */

	__u64	swapin_count;

	__u64	swapin_delay_total;

	__u64	swapin_delay_max;

	__u64	swapin_delay_min;



	/* cpu "wall-clock" running time

	 * On some architectures, value will adjust for cpu time stolen
@@ -170,11 +173,13 @@ struct taskstats { 
	__u64	freepages_count;

	__u64	freepages_delay_total;

	__u64	freepages_delay_max;

	__u64	freepages_delay_min;



	/* Delay waiting for thrashing page */

	__u64	thrashing_count;

	__u64	thrashing_delay_total;

	__u64	thrashing_delay_max;

	__u64	thrashing_delay_min;



	/* v10: 64-bit btime to avoid overflow */

	__u64	ac_btime64;		/* 64-bit begin time */
@@ -183,6 +188,7 @@ struct taskstats { 
	__u64	compact_count;

	__u64	compact_delay_total;

	__u64	compact_delay_max;

	__u64	compact_delay_min;



	/* v12 begin */

	__u32   ac_tgid;	/* thread group ID */
@@ -205,11 +211,13 @@ struct taskstats { 
	__u64    wpcopy_count;

	__u64    wpcopy_delay_total;

	__u64    wpcopy_delay_max;

	__u64    wpcopy_delay_min;



	/* v14: Delay waiting for IRQ/SOFTIRQ */

	__u64    irq_count;

	__u64    irq_delay_total;

	__u64    irq_delay_max;

	__u64    irq_delay_min;

	/* v15: add Delay max */

};

kernel/delayacct.c

+25 −7
Original line number Diff line number Diff line
@@ -95,7 +95,7 @@ void __delayacct_tsk_init(struct task_struct *tsk) 
 * Finish delay accounting for a statistic using its timestamps (@start),

 * accumulator (@total) and @count

 */

static void delayacct_end(raw_spinlock_t *lock, u64 *start, u64 *total, u32 *count, u64 *max)

static void delayacct_end(raw_spinlock_t *lock, u64 *start, u64 *total, u32 *count, u64 *max, u64 *min)

{

	s64 ns = local_clock() - *start;

	unsigned long flags;
@@ -106,6 +106,8 @@ static void delayacct_end(raw_spinlock_t *lock, u64 *start, u64 *total, u32 *cou 
		(*count)++;

		if (ns > *max)

			*max = ns;

		if (*min == 0 || ns < *min)

			*min = ns;

		raw_spin_unlock_irqrestore(lock, flags);

	}

}
@@ -125,7 +127,8 @@ void __delayacct_blkio_end(struct task_struct *p) 
		      &p->delays->blkio_start,

		      &p->delays->blkio_delay,

		      &p->delays->blkio_count,

		      &p->delays->blkio_delay_max);

		      &p->delays->blkio_delay_max,

		      &p->delays->blkio_delay_min);

}



int delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk)
@@ -157,6 +160,7 @@ int delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk) 
	d->cpu_count += t1;



	d->cpu_delay_max = tsk->sched_info.max_run_delay;

	d->cpu_delay_min = tsk->sched_info.min_run_delay;

	tmp = (s64)d->cpu_delay_total + t2;

	d->cpu_delay_total = (tmp < (s64)d->cpu_delay_total) ? 0 : tmp;

	tmp = (s64)d->cpu_run_virtual_total + t3;
@@ -170,24 +174,31 @@ int delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk) 
	/* zero XXX_total, non-zero XXX_count implies XXX stat overflowed */

	raw_spin_lock_irqsave(&tsk->delays->lock, flags);

	d->blkio_delay_max = tsk->delays->blkio_delay_max;

	d->blkio_delay_min = tsk->delays->blkio_delay_min;

	tmp = d->blkio_delay_total + tsk->delays->blkio_delay;

	d->blkio_delay_total = (tmp < d->blkio_delay_total) ? 0 : tmp;

	d->swapin_delay_max = tsk->delays->swapin_delay_max;

	d->swapin_delay_min = tsk->delays->swapin_delay_min;

	tmp = d->swapin_delay_total + tsk->delays->swapin_delay;

	d->swapin_delay_total = (tmp < d->swapin_delay_total) ? 0 : tmp;

	d->freepages_delay_max = tsk->delays->freepages_delay_max;

	d->freepages_delay_min = tsk->delays->freepages_delay_min;

	tmp = d->freepages_delay_total + tsk->delays->freepages_delay;

	d->freepages_delay_total = (tmp < d->freepages_delay_total) ? 0 : tmp;

	d->thrashing_delay_max = tsk->delays->thrashing_delay_max;

	d->thrashing_delay_min = tsk->delays->thrashing_delay_min;

	tmp = d->thrashing_delay_total + tsk->delays->thrashing_delay;

	d->thrashing_delay_total = (tmp < d->thrashing_delay_total) ? 0 : tmp;

	d->compact_delay_max = tsk->delays->compact_delay_max;

	d->compact_delay_min = tsk->delays->compact_delay_min;

	tmp = d->compact_delay_total + tsk->delays->compact_delay;

	d->compact_delay_total = (tmp < d->compact_delay_total) ? 0 : tmp;

	d->wpcopy_delay_max = tsk->delays->wpcopy_delay_max;

	d->wpcopy_delay_min = tsk->delays->wpcopy_delay_min;

	tmp = d->wpcopy_delay_total + tsk->delays->wpcopy_delay;

	d->wpcopy_delay_total = (tmp < d->wpcopy_delay_total) ? 0 : tmp;

	d->irq_delay_max = tsk->delays->irq_delay_max;

	d->irq_delay_min = tsk->delays->irq_delay_min;

	tmp = d->irq_delay_total + tsk->delays->irq_delay;

	d->irq_delay_total = (tmp < d->irq_delay_total) ? 0 : tmp;

	d->blkio_count += tsk->delays->blkio_count;
@@ -224,7 +235,8 @@ void __delayacct_freepages_end(void) 
		      &current->delays->freepages_start,

		      &current->delays->freepages_delay,

		      &current->delays->freepages_count,

		      &current->delays->freepages_delay_max);

		      &current->delays->freepages_delay_max,

		      &current->delays->freepages_delay_min);

}



void __delayacct_thrashing_start(bool *in_thrashing)
@@ -247,7 +259,8 @@ void __delayacct_thrashing_end(bool *in_thrashing) 
		      &current->delays->thrashing_start,

		      &current->delays->thrashing_delay,

		      &current->delays->thrashing_count,

		      &current->delays->thrashing_delay_max);

		      &current->delays->thrashing_delay_max,

		      &current->delays->thrashing_delay_min);

}



void __delayacct_swapin_start(void)
@@ -261,7 +274,8 @@ void __delayacct_swapin_end(void) 
		      &current->delays->swapin_start,

		      &current->delays->swapin_delay,

		      &current->delays->swapin_count,

		      &current->delays->swapin_delay_max);

		      &current->delays->swapin_delay_max,

		      &current->delays->swapin_delay_min);

}



void __delayacct_compact_start(void)
@@ -275,7 +289,8 @@ void __delayacct_compact_end(void) 
		      &current->delays->compact_start,

		      &current->delays->compact_delay,

		      &current->delays->compact_count,

		      &current->delays->compact_delay_max);

		      &current->delays->compact_delay_max,

		      &current->delays->compact_delay_min);

}



void __delayacct_wpcopy_start(void)
@@ -289,7 +304,8 @@ void __delayacct_wpcopy_end(void) 
		      &current->delays->wpcopy_start,

		      &current->delays->wpcopy_delay,

		      &current->delays->wpcopy_count,

		      &current->delays->wpcopy_delay_max);

		      &current->delays->wpcopy_delay_max,

		      &current->delays->wpcopy_delay_min);

}



void __delayacct_irq(struct task_struct *task, u32 delta)
@@ -301,6 +317,8 @@ void __delayacct_irq(struct task_struct *task, u32 delta) 
	task->delays->irq_count++;

	if (delta > task->delays->irq_delay_max)

		task->delays->irq_delay_max = delta;

	if (delta && (!task->delays->irq_delay_min || delta < task->delays->irq_delay_min))

		task->delays->irq_delay_min = delta;

	raw_spin_unlock_irqrestore(&task->delays->lock, flags);

}