From: Peter Zijlstra <peterz@infradead.org>
To: eranian@google.com
Cc: linux-kernel@vger.kernel.org, mingo@elte.hu, paulus@samba.org,
fweisbec@gmail.com, perfmon2-devel@lists.sf.net,
robert.richter@amd.com, eranian@gmail.com
Subject: Re: [PATCH] perf_events: add sampling period randomization support
Date: Tue, 02 Mar 2010 09:21:28 +0100 [thread overview]
Message-ID: <1267518088.25158.0.camel@laptop> (raw)
In-Reply-To: <1267510029-19750-1-git-send-email-eranian@google.com>
On Mon, 2010-03-01 at 22:07 -0800, eranian@google.com wrote:
> This patch adds support for randomizing the sampling period.
> Randomization is very useful to mitigate the bias that exists
> with sampling. The random number generator does not need to
> be sophisticated. This patch uses the builtin random32()
> generator.
>
> The user activates randomization by setting the perf_event_attr.random
> field to 1 and by passing a bitmask to control the range of variation
> above the base period. Period will vary from period to period & mask.
> Note that randomization is not available when a target interrupt rate
> (freq) is enabled.
>
> The last used period can be collected using the PERF_SAMPLE_PERIOD flag
> in sample_type.
>
> The patch has been tested on X86. There is also code for PowerPC but
> I could not test it.
I don't thikn we need to touch the arch code, we didn't need to for
frequency driven sampling, so I don't see a reason to do so for
randomization either.
next prev parent reply other threads:[~2010-03-02 9:13 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-02 6:07 [PATCH] perf_events: add sampling period randomization support eranian
2010-03-02 6:20 ` David Miller
2010-03-02 8:21 ` Peter Zijlstra [this message]
2010-03-02 10:53 ` Robert Richter
2010-03-02 11:41 ` Peter Zijlstra
2010-03-02 14:18 ` Robert Richter
2010-03-02 13:10 ` Frederic Weisbecker
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