linux-kernel - Re: [PATCH] perf lock: clean the options for perf record

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Date:	Thu, 10 Mar 2011 01:41:00 +0900
From:	Hitoshi Mitake <mitake@....info.waseda.ac.jp>
To:	Frederic Weisbecker <fweisbec@...il.com>
CC:	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	linux-kernel@...r.kernel.org, h.mitake@...il.com,
	Paul Mackerras <paulus@...ba.org>, Ingo Molnar <mingo@...e.hu>,
	Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
	Steven Rostedt <rostedt@...dmis.org>
Subject: Re: [PATCH] perf lock: clean the options for perf record

On 2011年03月04日 23:21, Frederic Weisbecker wrote:
> On Fri, Mar 04, 2011 at 02:58:19PM +0100, Peter Zijlstra wrote:
>> On Fri, 2011-03-04 at 14:56 +0100, Frederic Weisbecker wrote:
>>> lockstat is a global measurement since the boot.
>>
>> You can reset lockstat at any given time.
>
> Event though, that's still a global profiling. You can't have a per
> process or thread granularity.
>
> Or even more precise context for some future feature in perf that
> I have in mind and would like to implement soon, like counting/sampling
> an event only between two others. More exactly having two lists for
> each event:
>
> * activate
> * deactivate
>
> Those on the first list activate the target event when they overflow. (->start() )
> Those on the second list deactivate .... (->stop() )
>
> With events in activate and deactivate in the same context than the target,
> locking and permissions should be kept simple. Locking especially shouldn't be
> needed in the fast path. Then if that's needed we could think about a cross
> context things later.
>
> Plus an attr->start_state that decides if the first ->add() made is made
> with PERF_EF_STAT or not. (We then need to keep track of some activated/deactivated
> state across schedules).
>
> That's in fact the exclude_irq and exclude_softirq idea extended to any kind
> of existing event.
>

Do you mean that the event dropping in perf_tp_event_match() should be
extended for filtering hardirq and softirq? If so, it seems good.
I'd like to measure the effectiveness of it.
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