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Yang Yangakpm00
Yang Yang
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delayacct: track delays from IRQ/SOFTIRQ
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 52b1364("sched/psi: Add PSI_IRQ to track IRQ/SOFTIRQ pressure") Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Yang Yang <[email protected]> Cc: Jiang Xuexin <[email protected]> Cc: wangyong <[email protected]> Cc: junhua huang <[email protected]> Cc: Balbir Singh <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Jonathan Corbet <[email protected]> Cc: Juri Lelli <[email protected]> Cc: Peter Zijlstra <[email protected]> Signed-off-by: Andrew Morton <[email protected]>
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6 files changed

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lines changed

‎Documentation/accounting/delay-accounting.rst

+5-2
Original file line numberDiff line numberDiff line change
@@ -16,6 +16,7 @@ d) memory reclaim
1616
e) thrashing
1717
f) direct compact
1818
g) write-protect copy
19+
h) IRQ/SOFTIRQ
1920

2021
and makes these statistics available to userspace through
2122
the taskstats interface.
@@ -49,7 +50,7 @@ this structure. See
4950
for a description of the fields pertaining to delay accounting.
5051
It will generally be in the form of counters returning the cumulative
5152
delay seen for cpu, sync block I/O, swapin, memory reclaim, thrash page
52-
cache, direct compact, write-protect copy etc.
53+
cache, direct compact, write-protect copy, IRQ/SOFTIRQ etc.
5354

5455
Taking the difference of two successive readings of a given
5556
counter (say cpu_delay_total) for a task will give the delay
@@ -118,7 +119,9 @@ Get sum of delays, since system boot, for all pids with tgid 5::
118119
0 0 0.000ms
119120
COMPACT count delay total delay average
120121
0 0 0.000ms
121-
WPCOPY count delay total delay average
122+
WPCOPY count delay total delay average
123+
0 0 0.000ms
124+
IRQ count delay total delay average
122125
0 0 0.000ms
123126

124127
Get IO accounting for pid 1, it works only with -p::

‎include/linux/delayacct.h

+15
Original file line numberDiff line numberDiff line change
@@ -48,10 +48,13 @@ struct task_delay_info {
4848
u64 wpcopy_start;
4949
u64 wpcopy_delay; /* wait for write-protect copy */
5050

51+
u64 irq_delay; /* wait for IRQ/SOFTIRQ */
52+
5153
u32 freepages_count; /* total count of memory reclaim */
5254
u32 thrashing_count; /* total count of thrash waits */
5355
u32 compact_count; /* total count of memory compact */
5456
u32 wpcopy_count; /* total count of write-protect copy */
57+
u32 irq_count; /* total count of IRQ/SOFTIRQ */
5558
};
5659
#endif
5760

@@ -81,6 +84,7 @@ extern void __delayacct_compact_start(void);
8184
extern void __delayacct_compact_end(void);
8285
extern void __delayacct_wpcopy_start(void);
8386
extern void __delayacct_wpcopy_end(void);
87+
extern void __delayacct_irq(struct task_struct *task, u32 delta);
8488

8589
static inline void delayacct_tsk_init(struct task_struct *tsk)
8690
{
@@ -215,6 +219,15 @@ static inline void delayacct_wpcopy_end(void)
215219
__delayacct_wpcopy_end();
216220
}
217221

222+
static inline void delayacct_irq(struct task_struct *task, u32 delta)
223+
{
224+
if (!static_branch_unlikely(&delayacct_key))
225+
return;
226+
227+
if (task->delays)
228+
__delayacct_irq(task, delta);
229+
}
230+
218231
#else
219232
static inline void delayacct_init(void)
220233
{}
@@ -253,6 +266,8 @@ static inline void delayacct_wpcopy_start(void)
253266
{}
254267
static inline void delayacct_wpcopy_end(void)
255268
{}
269+
static inline void delayacct_irq(struct task_struct *task, u32 delta)
270+
{}
256271

257272
#endif /* CONFIG_TASK_DELAY_ACCT */
258273

‎include/uapi/linux/taskstats.h

+5-1
Original file line numberDiff line numberDiff line change
@@ -34,7 +34,7 @@
3434
*/
3535

3636

37-
#define TASKSTATS_VERSION 13
37+
#define TASKSTATS_VERSION 14
3838
#define TS_COMM_LEN 32 /* should be >= TASK_COMM_LEN
3939
* in linux/sched.h */
4040

@@ -198,6 +198,10 @@ struct taskstats {
198198
/* v13: Delay waiting for write-protect copy */
199199
__u64 wpcopy_count;
200200
__u64 wpcopy_delay_total;
201+
202+
/* v14: Delay waiting for IRQ/SOFTIRQ */
203+
__u64 irq_count;
204+
__u64 irq_delay_total;
201205
};
202206

203207

‎kernel/delayacct.c

+14
Original file line numberDiff line numberDiff line change
@@ -179,12 +179,15 @@ int delayacct_add_tsk(struct taskstats *d, struct task_struct *tsk)
179179
d->compact_delay_total = (tmp < d->compact_delay_total) ? 0 : tmp;
180180
tmp = d->wpcopy_delay_total + tsk->delays->wpcopy_delay;
181181
d->wpcopy_delay_total = (tmp < d->wpcopy_delay_total) ? 0 : tmp;
182+
tmp = d->irq_delay_total + tsk->delays->irq_delay;
183+
d->irq_delay_total = (tmp < d->irq_delay_total) ? 0 : tmp;
182184
d->blkio_count += tsk->delays->blkio_count;
183185
d->swapin_count += tsk->delays->swapin_count;
184186
d->freepages_count += tsk->delays->freepages_count;
185187
d->thrashing_count += tsk->delays->thrashing_count;
186188
d->compact_count += tsk->delays->compact_count;
187189
d->wpcopy_count += tsk->delays->wpcopy_count;
190+
d->irq_count += tsk->delays->irq_count;
188191
raw_spin_unlock_irqrestore(&tsk->delays->lock, flags);
189192

190193
return 0;
@@ -274,3 +277,14 @@ void __delayacct_wpcopy_end(void)
274277
&current->delays->wpcopy_delay,
275278
&current->delays->wpcopy_count);
276279
}
280+
281+
void __delayacct_irq(struct task_struct *task, u32 delta)
282+
{
283+
unsigned long flags;
284+
285+
raw_spin_lock_irqsave(&task->delays->lock, flags);
286+
task->delays->irq_delay += delta;
287+
task->delays->irq_count++;
288+
raw_spin_unlock_irqrestore(&task->delays->lock, flags);
289+
}
290+

‎kernel/sched/core.c

+1
Original file line numberDiff line numberDiff line change
@@ -704,6 +704,7 @@ static void update_rq_clock_task(struct rq *rq, s64 delta)
704704
rq->prev_irq_time += irq_delta;
705705
delta -= irq_delta;
706706
psi_account_irqtime(rq->curr, irq_delta);
707+
delayacct_irq(rq->curr, irq_delta);
707708
#endif
708709
#ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING
709710
if (static_key_false((&paravirt_steal_rq_enabled))) {

‎tools/accounting/getdelays.c

+18-12
Original file line numberDiff line numberDiff line change
@@ -198,17 +198,19 @@ static void print_delayacct(struct taskstats *t)
198198
printf("\n\nCPU %15s%15s%15s%15s%15s\n"
199199
" %15llu%15llu%15llu%15llu%15.3fms\n"
200200
"IO %15s%15s%15s\n"
201-
" %15llu%15llu%15.3fms\n"
201+
" %15llu%15llu%15.3fms\n"
202202
"SWAP %15s%15s%15s\n"
203-
" %15llu%15llu%15.3fms\n"
203+
" %15llu%15llu%15.3fms\n"
204204
"RECLAIM %12s%15s%15s\n"
205-
" %15llu%15llu%15.3fms\n"
205+
" %15llu%15llu%15.3fms\n"
206206
"THRASHING%12s%15s%15s\n"
207-
" %15llu%15llu%15.3fms\n"
207+
" %15llu%15llu%15.3fms\n"
208208
"COMPACT %12s%15s%15s\n"
209-
" %15llu%15llu%15.3fms\n"
209+
" %15llu%15llu%15.3fms\n"
210210
"WPCOPY %12s%15s%15s\n"
211-
" %15llu%15llu%15.3fms\n",
211+
" %15llu%15llu%15.3fms\n"
212+
"IRQ %15s%15s%15s\n"
213+
" %15llu%15llu%15.3fms\n",
212214
"count", "real total", "virtual total",
213215
"delay total", "delay average",
214216
(unsigned long long)t->cpu_count,
@@ -219,27 +221,31 @@ static void print_delayacct(struct taskstats *t)
219221
"count", "delay total", "delay average",
220222
(unsigned long long)t->blkio_count,
221223
(unsigned long long)t->blkio_delay_total,
222-
average_ms((double)t->blkio_delay_total, t->blkio_count),
224+
average_ms((double)t->blkio_delay_total, t->blkio_count),
223225
"count", "delay total", "delay average",
224226
(unsigned long long)t->swapin_count,
225227
(unsigned long long)t->swapin_delay_total,
226-
average_ms((double)t->swapin_delay_total, t->swapin_count),
228+
average_ms((double)t->swapin_delay_total, t->swapin_count),
227229
"count", "delay total", "delay average",
228230
(unsigned long long)t->freepages_count,
229231
(unsigned long long)t->freepages_delay_total,
230-
average_ms((double)t->freepages_delay_total, t->freepages_count),
232+
average_ms((double)t->freepages_delay_total, t->freepages_count),
231233
"count", "delay total", "delay average",
232234
(unsigned long long)t->thrashing_count,
233235
(unsigned long long)t->thrashing_delay_total,
234-
average_ms((double)t->thrashing_delay_total, t->thrashing_count),
236+
average_ms((double)t->thrashing_delay_total, t->thrashing_count),
235237
"count", "delay total", "delay average",
236238
(unsigned long long)t->compact_count,
237239
(unsigned long long)t->compact_delay_total,
238-
average_ms((double)t->compact_delay_total, t->compact_count),
240+
average_ms((double)t->compact_delay_total, t->compact_count),
239241
"count", "delay total", "delay average",
240242
(unsigned long long)t->wpcopy_count,
241243
(unsigned long long)t->wpcopy_delay_total,
242-
average_ms((double)t->wpcopy_delay_total, t->wpcopy_count));
244+
average_ms((double)t->wpcopy_delay_total, t->wpcopy_count),
245+
"count", "delay total", "delay average",
246+
(unsigned long long)t->irq_count,
247+
(unsigned long long)t->irq_delay_total,
248+
average_ms((double)t->irq_delay_total, t->irq_count));
243249
}
244250

245251
static void task_context_switch_counts(struct taskstats *t)

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