linux-kernel - Re: [perfmon2] [PATCH] perf: fix the is_software

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Message-ID: <7c86c4471001180457ue8738a5r25d717c939c6588c@mail.gmail.com>
Date:	Mon, 18 Jan 2010 13:57:33 +0100
From:	stephane eranian <eranian@...glemail.com>
To:	Frederic Weisbecker <fweisbec@...il.com>
Cc:	Peter Zijlstra <peterz@...radead.org>, perfmon2-devel@...ts.sf.net,
	linux-kernel@...r.kernel.org,
	Stephane Eranian <eranian@...gle.com>, paulus@...ba.org,
	mingo@...e.hu, davem@...emloft.net
Subject: Re: [perfmon2] [PATCH] perf: fix the is_software_event() definition

On Mon, Jan 18, 2010 at 1:07 PM, Frederic Weisbecker <fweisbec@...il.com> wrote:
> On Mon, Jan 18, 2010 at 12:53:36PM +0100, Peter Zijlstra wrote:
>> On Mon, 2010-01-18 at 12:13 +0100, Peter Zijlstra wrote:
>> > On Sun, 2010-01-17 at 15:12 +0100, Frederic Weisbecker wrote:
>> >
>> > > You need to also call pmu->disable() if it is a software event,
>> > > because a breakpoint needs to be unregistered in hardware level
>> > > too.
>> >
>> > breakpoint isn't a software pmu. But yeah, enable and disable need to
>> > match.
>>
>> That is, it shouldn't be a software pmu, because we assume software
>> events can always be scheduled, whereas that's definitely not so for the
>> breakpoint one.
>>
>> Which seems to suggest the following
>>
>> ---
>> Subject: perf: fix the is_software_event() definition
>>
>> When adding the breakpoint pmu Frederic forgot to exclude it from being
>> a software event. While we're at it, make it an inclusive expression.
>>
>> Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>
>
>
>
> Agreed.
>
> But then Stephane will need to update his patch and use
> something else than is_software_event() to guess if an event
> needs its pmu->enable/disable to be called.
>
> A kind of helper that can tell: I am not handled by
> hw_perf_group_sched_in()
>
Then, we should use something that checks if the event
is handled by the X86 PMU layer:

int is_x86_hw_event(struct perf_event *event)
{
   return event->pmu == x86_pmu;
}
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