From: Yang Yang <[email protected]>
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")
Signed-off-by: Yang Yang <[email protected]>
Cc: Jiang Xuexin <[email protected]>
Cc: wangyong <[email protected]>
Cc: junhua huang <[email protected]>
---
Documentation/accounting/delay-accounting.rst | 7 +++--
include/linux/delayacct.h | 15 ++++++++++
include/uapi/linux/taskstats.h | 6 +++-
kernel/delayacct.c | 14 +++++++++
kernel/sched/core.c | 1 +
tools/accounting/getdelays.c | 30 +++++++++++--------
6 files changed, 58 insertions(+), 15 deletions(-)
diff --git a/Documentation/accounting/delay-accounting.rst b/Documentation/accounting/delay-accounting.rst
index 79f537c9f160..f61c01fc376e 100644
--- a/Documentation/accounting/delay-accounting.rst
+++ b/Documentation/accounting/delay-accounting.rst
@@ -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
@@ -118,7 +119,9 @@ Get sum of delays, since system boot, for all pids with tgid 5::
0 0 0.000ms
COMPACT count delay total delay average
0 0 0.000ms
- WPCOPY count delay total delay average
+ 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::
diff --git a/include/linux/delayacct.h b/include/linux/delayacct.h
index 0da97dba9ef8..6639f48dac36 100644
--- a/include/linux/delayacct.h
+++ b/include/linux/delayacct.h
@@ -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 */
diff --git a/include/uapi/linux/taskstats.h b/include/uapi/linux/taskstats.h
index a7f5b11a8f1b..b50b2eb257a0 100644
--- a/include/uapi/linux/taskstats.h
+++ b/include/uapi/linux/taskstats.h
@@ -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;
};
diff --git a/kernel/delayacct.c b/kernel/delayacct.c
index e39cb696cfbd..6f0c358e73d8 100644
--- a/kernel/delayacct.c
+++ b/kernel/delayacct.c
@@ -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)
¤t->delays->wpcopy_delay,
¤t->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);
+}
+
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index a380f34789a2..8127fa8dfde7 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -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((¶virt_steal_rq_enabled))) {
diff --git a/tools/accounting/getdelays.c b/tools/accounting/getdelays.c
index 23a15d8f2bf4..1334214546d7 100644
--- a/tools/accounting/getdelays.c
+++ b/tools/accounting/getdelays.c
@@ -198,17 +198,19 @@ static void print_delayacct(struct taskstats *t)
printf("\n\nCPU %15s%15s%15s%15s%15s\n"
" %15llu%15llu%15llu%15llu%15.3fms\n"
"IO %15s%15s%15s\n"
- " %15llu%15llu%15.3fms\n"
+ " %15llu%15llu%15.3fms\n"
"SWAP %15s%15s%15s\n"
- " %15llu%15llu%15.3fms\n"
+ " %15llu%15llu%15.3fms\n"
"RECLAIM %12s%15s%15s\n"
- " %15llu%15llu%15.3fms\n"
+ " %15llu%15llu%15.3fms\n"
"THRASHING%12s%15s%15s\n"
- " %15llu%15llu%15.3fms\n"
+ " %15llu%15llu%15.3fms\n"
"COMPACT %12s%15s%15s\n"
- " %15llu%15llu%15.3fms\n"
+ " %15llu%15llu%15.3fms\n"
"WPCOPY %12s%15s%15s\n"
- " %15llu%15llu%15.3fms\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",
(unsigned long long)t->cpu_count,
@@ -219,27 +221,31 @@ static void print_delayacct(struct taskstats *t)
"count", "delay total", "delay average",
(unsigned long long)t->blkio_count,
(unsigned long long)t->blkio_delay_total,
- average_ms((double)t->blkio_delay_total, t->blkio_count),
+ average_ms((double)t->blkio_delay_total, t->blkio_count),
"count", "delay total", "delay average",
(unsigned long long)t->swapin_count,
(unsigned long long)t->swapin_delay_total,
- average_ms((double)t->swapin_delay_total, t->swapin_count),
+ average_ms((double)t->swapin_delay_total, t->swapin_count),
"count", "delay total", "delay average",
(unsigned long long)t->freepages_count,
(unsigned long long)t->freepages_delay_total,
- average_ms((double)t->freepages_delay_total, t->freepages_count),
+ average_ms((double)t->freepages_delay_total, t->freepages_count),
"count", "delay total", "delay average",
(unsigned long long)t->thrashing_count,
(unsigned long long)t->thrashing_delay_total,
- average_ms((double)t->thrashing_delay_total, t->thrashing_count),
+ average_ms((double)t->thrashing_delay_total, t->thrashing_count),
"count", "delay total", "delay average",
(unsigned long long)t->compact_count,
(unsigned long long)t->compact_delay_total,
- average_ms((double)t->compact_delay_total, t->compact_count),
+ average_ms((double)t->compact_delay_total, t->compact_count),
"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)
--
2.25.1
On Sat, 8 Apr 2023 17:28:35 +0800 (CST) <[email protected]> wrote:
> From: Yang Yang <[email protected]>
>
> 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
Seems sensible. I'm not sure who's the best person to review/ack this
nowadays.
We're somewhat double-accounting. Delays due to, for example, IO will
already include delays from IRQ activity. But it's presumably a minor
thing and I don't see why anyone would care.
> We're somewhat double-accounting. Delays due to, for example, IO will
> already include delays from IRQ activity. But it's presumably a minor
> thing and I don't see why anyone would care.
Thanks for your reviewing! I also think double-accounting should be OK, some
one who is tunning IO or IRQ could focus on the related delay respectively.
And PSI has the same logic when calculate IRQ or IO pressure.