linux-kernel - Re: [PATCH 2/2] tracing/workqueue: Rename workqueue_execute to worklet_entry and add worklet

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Message-Id: <20090924092023.B645.A69D9226@jp.fujitsu.com>
Date:	Thu, 24 Sep 2009 09:22:37 +0900 (JST)
From:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
To:	Frederic Weisbecker <fweisbec@...il.com>
Cc:	kosaki.motohiro@...fujitsu.com, Anton Blanchard <anton@...ba.org>,
	Li Zefan <lizf@...fujitsu.com>,
	Zhaolei <zhaolei@...fujitsu.com>,
	Lai Jiangshan <laijs@...fujitsu.com>,
	Ingo Molnar <mingo@...e.hu>,
	Steven Rostedt <rostedt@...dmis.org>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] tracing/workqueue: Rename workqueue_execute to worklet_entry and add worklet_exit

Hi

> In Kosaki's patch, we had the work struct address displayed too.
> Your version is supposed to be sufficient because we know a workqueue
> serializes its works. Then we know that an exit event will always follow
> and match the previous entry event from the same workqueue thread.
> The workqueue pid then provides a sufficient key for that.
> 
> That said, we should worry about possible lost events from
> perf in some circumstances. And userspace profiling needs something
> to ensure the accuracy about this entry/exit pair.
> 
> We could have:
> 	entry work1
> 	exit work 1 <--- lost event
> 	entry work2 <--- lost event
> 	exit work2
> 
> And then the pair would be misinterpreted.
> 
> (Although we could have even other misinterpretation
> with other kind of scenarios, even if we have this work
> address. But that's still more safety).
> 
> So I'd prefer to keep Kosaki's idea about these keys.
> But I prefer your event naming.
> 
> May be I can unearth Kosaki's patch, change it with your naming
> and add your Signed-off-by?
> 
> Kosaki, no problem about it?

Sure.
Thank you paid attention my patch :-)





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