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

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Date:	Mon, 18 Jan 2010 13:53:41 +0100
From:	stephane eranian <eranian@...glemail.com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Frederic Weisbecker <fweisbec@...il.com>,
	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 12:53 PM, Peter Zijlstra <peterz@...radead.org> 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>
> ---
>  include/linux/perf_event.h |   10 +++++++---
>  1 files changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h
> index c66b34f..835ba26 100644
> --- a/include/linux/perf_event.h
> +++ b/include/linux/perf_event.h
> @@ -814,9 +814,13 @@ extern int perf_event_overflow(struct perf_event *event, int nmi,
>  */
>  static inline int is_software_event(struct perf_event *event)
>  {
> -       return (event->attr.type != PERF_TYPE_RAW) &&
> -               (event->attr.type != PERF_TYPE_HARDWARE) &&
> -               (event->attr.type != PERF_TYPE_HW_CACHE);
> +       switch (event->attr.type) {
> +       case PERF_TYPE_SOFTWARE:
> +       case PERF_TYPE_TRACEPOINT:
> +       case PERF_TYPE_HW_CACHE:
> +               return 1;
> +       }
> +       return 0;
>  }
>
>  extern atomic_t perf_swevent_enabled[PERF_COUNT_SW_MAX];
>
PERF_TYPE_HW_CACHE is a hardware PMU event.


>
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