From: Peter Zijlstra <peterz@infradead.org>
To: Robert Richter <robert.richter@amd.com>
Cc: eranian@google.com, linux-kernel@vger.kernel.org, mingo@elte.hu,
paulus@samba.org, fweisbec@gmail.com,
perfmon2-devel@lists.sf.net, eranian@gmail.com
Subject: Re: [PATCH] perf_events: add sampling period randomization support
Date: Tue, 02 Mar 2010 12:41:18 +0100 [thread overview]
Message-ID: <1267530078.25158.41.camel@laptop> (raw)
In-Reply-To: <20100302105314.GF13205@erda.amd.com>
On Tue, 2010-03-02 at 11:53 +0100, Robert Richter wrote:
>
> Only adding the random value will lead to longer sample periods on
> average. To compensate this you could calculate something like:
>
> event->hw.sample_period = event->attr.sample_period + (new_seed & mask) - (mask >> 1);
Or cheat and do something like:
sample_period ^= (new_seed & mask);
next prev parent reply other threads:[~2010-03-02 11:41 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
2010-03-02 10:53 ` Robert Richter
2010-03-02 11:41 ` Peter Zijlstra [this message]
2010-03-02 14:18 ` Robert Richter
2010-03-02 13:10 ` Frederic Weisbecker
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