From: Peter Zijlstra <peterz@infradead.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Dongsheng Yang <dongsheng081251@gmail.com>,
"yangds.fnst" <yangds.fnst@cn.fujitsu.com>,
linux-kernel@vger.kernel.org, mingo@redhat.com,
bsegall@google.com
Subject: Re: [PATCH] sched: Distinguish sched_wakeup event when wake up a task which did schedule out or not.
Date: Mon, 12 May 2014 08:47:30 +0200 [thread overview]
Message-ID: <20140512064730.GI30445@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <20140511145224.00412e59@gandalf.local.home>
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On Sun, May 11, 2014 at 02:52:24PM -0400, Steven Rostedt wrote:
> On Sun, 11 May 2014 18:35:31 +0200
> Peter Zijlstra <peterz@infradead.org> wrote:
>
>
> > So if the wait side has already observed cond==false, then without the
> > wakeup, which still potentially has ->on_rq == true, it would block.
> > Therefore the wakeup is a _real_ wakeup.
> >
> > We fundamentally cannot know, on the wake side, if the wait side has or
> > has not observed cond, and therefore the distinction you're trying to
> > make is a false one.
>
> I believe you may be misunderstanding Dongsheng. It has nothing to do
> with the wake condition. But the "success" is basically saying, "did I
> move the task on to the run queue?". That's a relevant piece of
> information that the wake up event isn't currently showing.
>
> Let me ask you this; with Donsheng's patch, will there ever be a
> sched_switch event when the wakeup event sees 'false' and the
> sched_switch event see the task with a state other than "R"? And if so,
> how did the task doing the wakeup event, wake up that task?
But that has nothing what so fucking ever to do with 'success'. Reusing
that trace argument for something entirely different is just retarded.
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next prev parent reply other threads:[~2014-05-12 6:47 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-04-15 12:32 [PATCH 0/8] perf sched: Add trace event for sched wait Dongsheng Yang
2014-04-15 12:32 ` [PATCH 1/8] sched & trace: Add a trace event for wait Dongsheng Yang
2014-04-15 13:49 ` Peter Zijlstra
2014-04-16 14:23 ` Steven Rostedt
2014-04-15 12:32 ` [PATCH 2/8] sched/wait: Add trace point before add task into wait queue Dongsheng Yang
2014-04-15 12:32 ` [PATCH 3/8] sched/wait: Use __add_wait_queue{_tail}_exclusive() as possible Dongsheng Yang
2014-04-15 13:49 ` Peter Zijlstra
2014-04-16 9:51 ` Dongsheng Yang
2014-04-15 12:32 ` [PATCH 4/8] sched/core: Skip wakeup when task is already running Dongsheng Yang
2014-04-15 13:53 ` Peter Zijlstra
2014-04-16 10:22 ` Dongsheng Yang
2014-04-22 11:56 ` Dongsheng Yang
2014-04-22 13:23 ` Peter Zijlstra
2014-04-22 17:10 ` bsegall
2014-04-22 17:53 ` Steven Rostedt
2014-04-22 18:18 ` Peter Zijlstra
2014-05-05 6:32 ` Dongsheng Yang
2014-05-05 6:34 ` [PATCH] sched: Move the wakeup tracepoint from ttwu_do_wakeup() to ttwu_activate() Dongsheng Yang
2014-05-05 14:00 ` Steven Rostedt
2014-05-06 0:19 ` Dongsheng Yang
2014-05-06 0:26 ` Dongsheng Yang
2014-05-06 2:06 ` Steven Rostedt
2014-05-06 1:29 ` Dongsheng Yang
2014-05-06 1:52 ` [PATCH] sched: Distinguish sched_wakeup event when wake up a task which did schedule out or not Dongsheng Yang
2014-05-09 0:16 ` Dongsheng Yang
2014-05-09 1:27 ` Steven Rostedt
2014-05-10 15:29 ` Peter Zijlstra
[not found] ` <536F90BE.2080806@gmail.com>
2014-05-11 15:24 ` Fwd: " Dongsheng Yang
2014-05-11 16:35 ` Peter Zijlstra
2014-05-11 18:52 ` Steven Rostedt
2014-05-12 6:47 ` Peter Zijlstra [this message]
2014-05-12 8:58 ` Dongsheng Yang
2014-05-12 14:09 ` Steven Rostedt
2014-05-12 15:09 ` Peter Zijlstra
2014-05-12 15:17 ` Steven Rostedt
2014-05-12 15:28 ` Peter Zijlstra
2014-04-15 12:32 ` [PATCH 5/8] perf tools: record and process sched:sched_wait event Dongsheng Yang
2014-04-15 12:32 ` [PATCH 6/8] perf tools: add missing event for perf sched record Dongsheng Yang
2014-04-15 12:32 ` [PATCH 7/8] perf tools: Adapt the TASK_STATE_TO_CHAR_STR to new value in kernel space Dongsheng Yang
2014-04-15 12:32 ` [PATCH 8/8] perf tools: Clarify the output of perf sched map Dongsheng Yang
2014-04-15 13:54 ` [PATCH 0/8] perf sched: Add trace event for sched wait Peter Zijlstra
2014-04-16 10:28 ` Dongsheng Yang
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