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delayacct: track delays from IRQ/SOFTIRQ

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Delay accounting does not track the delay of IRQ/SOFTIRQ.  While
IRQ/SOFTIRQ could have obvious impact on some workloads productivity, such
as when workloads are running on system which is busy handling network
IRQ/SOFTIRQ.

Get the delay of IRQ/SOFTIRQ could help users to reduce such delay.  Such
as setting interrupt affinity or task affinity, using kernel thread for
NAPI etc.  This is inspired by "sched/psi: Add PSI_IRQ to track
IRQ/SOFTIRQ pressure"[1].  Also fix some code indent problems of older
code.

And update tools/accounting/getdelays.c:
    / # ./getdelays -p 156 -di
    print delayacct stats ON
    printing IO accounting
    PID     156

    CPU             count     real total  virtual total    delay total  delay average
                       15       15836008       16218149      275700790         18.380ms
    IO              count    delay total  delay average
                        0              0          0.000ms
    SWAP            count    delay total  delay average
                        0              0          0.000ms
    RECLAIM         count    delay total  delay average
                        0              0          0.000ms
    THRASHING       count    delay total  delay average
                        0              0          0.000ms
    COMPACT         count    delay total  delay average
                        0              0          0.000ms
    WPCOPY          count    delay total  delay average
                       36        7586118          0.211ms
    IRQ             count    delay total  delay average
                       42         929161          0.022ms

[1] commit 52b1364ba0b1("sched/psi: Add PSI_IRQ to track IRQ/SOFTIRQ pressure")

Link: https://lkml.kernel.org/r/202304081728353557233@zte.com.cn
Signed-off-by: Yang Yang <yang.yang29@zte.com.cn>
Cc: Jiang Xuexin <jiang.xuexin@zte.com.cn>
Cc: wangyong <wang.yong12@zte.com.cn>
Cc: junhua huang <huang.junhua@zte.com.cn>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Yang Yang 2023-04-08 17:28:35 +08:00 committed by Andrew Morton
parent 29692fc92c
commit a3b2aeac9d
6 changed files with 58 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
Documentation/accounting/delay-accounting.rst
View File

@ -16,6 +16,7 @@ d) memory reclaim
e) thrashing
f) direct compact
g) write-protect copy
h) IRQ/SOFTIRQ
and makes these statistics available to userspace through
the taskstats interface.
@ -49,7 +50,7 @@ this structure. See
for a description of the fields pertaining to delay accounting.
It will generally be in the form of counters returning the cumulative
delay seen for cpu, sync block I/O, swapin, memory reclaim, thrash page
cache, direct compact, write-protect copy etc.
cache, direct compact, write-protect copy, IRQ/SOFTIRQ etc.
Taking the difference of two successive readings of a given
counter (say cpu_delay_total) for a task will give the delay
@ -120,6 +121,8 @@ Get sum of delays, since system boot, for all pids with tgid 5::
0 0 0.000ms
WPCOPY count delay total delay average
0 0 0.000ms
IRQ count delay total delay average
0 0 0.000ms
Get IO accounting for pid 1, it works only with -p::

15
include/linux/delayacct.h
View File

@ -48,10 +48,13 @@ struct task_delay_info {
u64 wpcopy_start;
u64 wpcopy_delay; /* wait for write-protect copy */
u64 irq_delay; /* wait for IRQ/SOFTIRQ */
u32 freepages_count; /* total count of memory reclaim */
u32 thrashing_count; /* total count of thrash waits */
u32 compact_count; /* total count of memory compact */
u32 wpcopy_count; /* total count of write-protect copy */
u32 irq_count; /* total count of IRQ/SOFTIRQ */
};
#endif
@ -81,6 +84,7 @@ extern void __delayacct_compact_start(void);
extern void __delayacct_compact_end(void);
extern void __delayacct_wpcopy_start(void);
extern void __delayacct_wpcopy_end(void);
extern void __delayacct_irq(struct task_struct *task, u32 delta);
static inline void delayacct_tsk_init(struct task_struct *tsk)
{
@ -215,6 +219,15 @@ static inline void delayacct_wpcopy_end(void)
__delayacct_wpcopy_end();
}
static inline void delayacct_irq(struct task_struct *task, u32 delta)
{
if (!static_branch_unlikely(&delayacct_key))
return;
if (task->delays)
__delayacct_irq(task, delta);
}
#else
static inline void delayacct_init(void)
{}
@ -253,6 +266,8 @@ static inline void delayacct_wpcopy_start(void)
{}
static inline void delayacct_wpcopy_end(void)
{}
static inline void delayacct_irq(struct task_struct *task, u32 delta)
{}
#endif /* CONFIG_TASK_DELAY_ACCT */

6
include/uapi/linux/taskstats.h
View File

@ -34,7 +34,7 @@
*/
#define TASKSTATS_VERSION 13
#define TASKSTATS_VERSION 14
#define TS_COMM_LEN 32 /* should be >= TASK_COMM_LEN
* in linux/sched.h */
@ -198,6 +198,10 @@ struct taskstats {
/* v13: Delay waiting for write-protect copy */
__u64 wpcopy_count;
__u64 wpcopy_delay_total;
/* v14: Delay waiting for IRQ/SOFTIRQ */
__u64 irq_count;
__u64 irq_delay_total;
};

14
kernel/delayacct.c
View File

@ -179,12 +179,15 @@ int delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk)
d->compact_delay_total = (tmp < d->compact_delay_total) ? 0 : tmp;
tmp = d->wpcopy_delay_total + tsk->delays->wpcopy_delay;
d->wpcopy_delay_total = (tmp < d->wpcopy_delay_total) ? 0 : tmp;
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;
d->swapin_count += tsk->delays->swapin_count;
d->freepages_count += tsk->delays->freepages_count;
d->thrashing_count += tsk->delays->thrashing_count;
d->compact_count += tsk->delays->compact_count;
d->wpcopy_count += tsk->delays->wpcopy_count;
d->irq_count += tsk->delays->irq_count;
raw_spin_unlock_irqrestore(&tsk->delays->lock, flags);
return 0;
@ -274,3 +277,14 @@ void __delayacct_wpcopy_end(void)
&current->delays->wpcopy_delay,
&current->delays->wpcopy_count);
}
void __delayacct_irq(struct task_struct *task, u32 delta)
{
unsigned long flags;
raw_spin_lock_irqsave(&task->delays->lock, flags);
task->delays->irq_delay += delta;
task->delays->irq_count++;
raw_spin_unlock_irqrestore(&task->delays->lock, flags);
}

1
kernel/sched/core.c
View File

@ -704,6 +704,7 @@ static void update_rq_clock_task(struct rq *rq, s64 delta)
rq->prev_irq_time += irq_delta;
delta -= irq_delta;
psi_account_irqtime(rq->curr, irq_delta);
delayacct_irq(rq->curr, irq_delta);
#endif
#ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING
if (static_key_false((&paravirt_steal_rq_enabled))) {

8
tools/accounting/getdelays.c
View File

@ -208,6 +208,8 @@ static void print_delayacct(struct taskstats *t)
"COMPACT %12s%15s%15s\n"
" %15llu%15llu%15.3fms\n"
"WPCOPY %12s%15s%15s\n"
" %15llu%15llu%15.3fms\n"
"IRQ %15s%15s%15s\n"
" %15llu%15llu%15.3fms\n",
"count", "real total", "virtual total",
"delay total", "delay average",
@ -239,7 +241,11 @@ static void print_delayacct(struct taskstats *t)
"count", "delay total", "delay average",
(unsigned long long)t->wpcopy_count,
(unsigned long long)t->wpcopy_delay_total,
average_ms((double)t->wpcopy_delay_total, t->wpcopy_count));
average_ms((double)t->wpcopy_delay_total, t->wpcopy_count),
"count", "delay total", "delay average",
(unsigned long long)t->irq_count,
(unsigned long long)t->irq_delay_total,
average_ms((double)t->irq_delay_total, t->irq_count));
}
static void task_context_switch_counts(struct taskstats *t)