linux-kernel - Re: [PATCH] perf, x86: catch spurious interrupts after disabling counters

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Message-ID: <AANLkTimPh7bo1XxTK8bnisvLq8pCySUV6XJspw8m-Wwa@mail.gmail.com>
Date:	Wed, 15 Sep 2010 22:21:10 +0200
From:	Stephane Eranian <eranian@...gle.com>
To:	Cyrill Gorcunov <gorcunov@...il.com>
Cc:	Robert Richter <robert.richter@....com>,
	Ingo Molnar <mingo@...e.hu>,
	Peter Zijlstra <peterz@...radead.org>,
	Don Zickus <dzickus@...hat.com>,
	"fweisbec@...il.com" <fweisbec@...il.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"ying.huang@...el.com" <ying.huang@...el.com>,
	"ming.m.lin@...el.com" <ming.m.lin@...el.com>,
	"yinghai@...nel.org" <yinghai@...nel.org>,
	"andi@...stfloor.org" <andi@...stfloor.org>
Subject: Re: [PATCH] perf, x86: catch spurious interrupts after disabling counters

When you do perf record foo, it's equivalent to
perf record -e cycles:uk -F 1000 foo

I think there is a problem with perf record in case you provide
multiple events. It is going to sample on all of them at the same
frequency. You may not always want that, but I don't think there
is a way to change that.


On Wed, Sep 15, 2010 at 9:34 PM, Cyrill Gorcunov <gorcunov@...il.com> wrote:
> On Wed, Sep 15, 2010 at 08:44:24PM +0200, Robert Richter wrote:
> ...
>>
>> Do you know at which period the counters running for the following?
>>
>>  perf record ./hackbench 10
>>  perf record -e cycles -e instructions -e cache-references \
>>      -e cache-misses -e branch-misses -a -- <cmd>
>>
>> I couldn't find something about this in the man page.
>>
>
> It's on top of tools/perf/builtin-record.c so by default they
> should be sampled with frequency 1KHz. Frederic or Peter knows
> for sure ;)
>
>        -- Cyrill
>
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