Re: [PATCH] perf sched: fix wrong conversion of task state

From	関山友輝 / SEKIYAMA，TOMOKI <tomoki.sekiyama.qu@hitachi.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH] perf sched: fix wrong conversion of task state
Date	2016-07-29 04:40 +0200
Message-ID	<s05Sp-6R6-3@gated-at.bofh.it> (permalink)
References	(1 earlier) <rZxQJ-ug-11@gated-at.bofh.it> <rZzzb-1Cb-11@gated-at.bofh.it> <rZAlA-1Uf-5@gated-at.bofh.it> <s05Sp-6R6-5@gated-at.bofh.it> <rZUtY-7qU-17@gated-at.bofh.it>
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On 2016/07/28 23:26、David Ahern wrote:
>> But that means we cannot handle preemption correctly as far as
>> sched:sched_switch
>> event uses TASK_STATE_MAX to mark preempted tasks.
>> 
>> Should we stop using TASK_STATE_MAX for preempted tasks in ftrace and
>> use (1 << 63) or something that doesn't change on kernel version instead?
> 
> ftrace printing is within the kernel so it has consistency.
Agreed.

> It is the save data and analyze later use case that can not assume TASK_STATE_MAX means preemption since the value of TASK_STATE_MAX is kernel version dependent.

That means we cannot measure delay by preemption using perf sched latency. :(
It might be helpful if the preemption mark becomes kernel-version-independent at least for future kernel version..

Anyway, this time I will post the patch to fix only invalid conversion issue of task state with this patch.

Thanks,
Tomoki Sekiyama

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[PATCH] perf sched: fix wrong conversion of task state Tomoki Sekiyama <tomoki.sekiyama.qu@hitachi.com> - 2016-07-27 15:20 +0200
  Re: [PATCH] perf sched: fix wrong conversion of task state David Ahern <dsahern@gmail.com> - 2016-07-27 16:20 +0200
    RE: [PATCH] perf sched: fix wrong conversion of task state 関山友輝 / SEKIYAMA，TOMOKI   <tomoki.sekiyama.qu@hitachi.com> - 2016-07-27 18:10 +0200
    RE: [PATCH] perf sched: fix wrong conversion of task state 関山友輝 / SEKIYAMA，TOMOKI   <tomoki.sekiyama.qu@hitachi.com> - 2016-07-27 18:10 +0200
      Re: [PATCH] perf sched: fix wrong conversion of task state David Ahern <dsahern@gmail.com> - 2016-07-27 19:00 +0200
        RE: [PATCH] perf sched: fix wrong conversion of task state "Tomoki Sekiyama" <tomoki.sekiyama.qu@hitachi.com> - 2016-07-28 05:20 +0200
          Re: [PATCH] perf sched: fix wrong conversion of task state David Ahern <dsahern@gmail.com> - 2016-07-28 16:30 +0200
            Re: [PATCH] perf sched: fix wrong conversion of task state 関山友輝 / SEKIYAMA，TOMOKI   <tomoki.sekiyama.qu@hitachi.com> - 2016-07-29 04:40 +0200

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