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

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Date:	Mon, 18 Jan 2010 14:06:30 +0100
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	eranian@...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

2010/1/18 stephane eranian <eranian@...glemail.com>:
> 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;
> }
>

Yeah. I missed this patch from Peter in its answer. Looks good.
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