Re: [External] Re: [PATCH 1/2] perf sched timehist: Add --show-prio option

From: Yang Jihong
Date: Thu Aug 08 2024 - 21:59:24 EST


Hello,

On 8/9/24 02:42, Madadi Vineeth Reddy wrote:
Hi Yang Jihong,

On 06/08/24 07:27, Yang Jihong wrote:
The --show-prio option is used to display the priority of task.
It is disabled by default, which is consistent with original behavior.

The display format is xxx (priority does not change during task running)
or xxx->yyy (priority changes during task running)


I had done the following steps.
1) Ran 'perf sched record stress-ng --cpu 32 -l 50 --timeout 40s'
2) Changed the nice value of stress-ng while the record was going on.
ps -C stress-ng -o pid=
64195

renice -n 10 -p 64195

3) Then ran 'perf sched timehist --show-prio'

343918.720052 [0015] stress-ng[64195] 120 0.013 0.013 21.719
.
.
343958.797257 [0009] stress-ng[64195] 130 40076.812 0.007 0.393

The output shows the final priority change of stress-ng from 120 to 130,
but the transition format xxx->yyy is not displayed.

Am I missing something?


1. I think it may be because when change the priority of stress-ng, the stress-ng task had been sched_out and did not run.

2.
sched_switch: A -> B(prio1)
sched_switch: B(prio_2) -> C

The specific details are that:
first process the first sched_switch event, read the priority of task B, as prio1.
then process the second sched_switch event, read the priority of task B, as prio2.

Only when change the priority of task B, it is in the running state, will show prio1->prio2

Thanks,
Yang.