From: Peter Zijlstra <peterz@infradead.org>
To: Kan Liang <kan.liang@intel.com>
Cc: linux-kernel@vger.kernel.org, mingo@kernel.org,
acme@infradead.org, eranian@google.com, andi@firstfloor.org
Subject: Re: [PATCH V6 4/6] perf, x86: handle multiple records in PEBS buffer
Date: Wed, 15 Apr 2015 20:28:36 +0200 [thread overview]
Message-ID: <20150415182836.GX23123@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <1428597466-8154-5-git-send-email-kan.liang@intel.com>
On Thu, Apr 09, 2015 at 12:37:44PM -0400, Kan Liang wrote:
> The only way you can get a lot of collision is when you count the same
> thing multiple times. But it is not a useful configuration.
Not entirely true; I _think_ you can be unfortunate if you measure with
a userspace only PEBS event along with either a kernel or unrestricted
PEBS event. Imagine the event triggering and setting the overflow flag
right before entering the kernel. Then all kernel side events will end
up with multiple bits set.
next prev parent reply other threads:[~2015-04-15 18:28 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-09 16:37 [PATCH V6 0/6] large PEBS interrupt threshold Kan Liang
2015-04-09 16:37 ` [PATCH V6 1/6] perf, x86: use the PEBS auto reload mechanism when possible Kan Liang
2015-04-09 16:37 ` [PATCH V6 2/6] perf, x86: introduce setup_pebs_sample_data() Kan Liang
2015-04-09 16:37 ` [PATCH V6 3/6] perf, x86: large PEBS interrupt threshold Kan Liang
2015-04-15 17:14 ` Peter Zijlstra
2015-04-15 17:48 ` Liang, Kan
2015-04-15 18:10 ` Peter Zijlstra
2015-04-15 18:05 ` Peter Zijlstra
2015-04-15 18:35 ` Liang, Kan
2015-04-15 18:41 ` Peter Zijlstra
2015-04-16 18:45 ` Peter Zijlstra
2015-04-09 16:37 ` [PATCH V6 4/6] perf, x86: handle multiple records in PEBS buffer Kan Liang
2015-04-09 21:01 ` Andi Kleen
2015-04-15 18:28 ` Peter Zijlstra [this message]
2015-04-15 18:36 ` Peter Zijlstra
2015-04-16 12:53 ` Peter Zijlstra
2015-04-17 8:11 ` Peter Zijlstra
2015-04-17 12:50 ` Liang, Kan
2015-04-17 13:12 ` Peter Zijlstra
2015-04-17 14:19 ` Liang, Kan
2015-04-17 14:44 ` Peter Zijlstra
2015-04-17 18:20 ` Andi Kleen
2015-04-17 18:25 ` Peter Zijlstra
2015-04-09 16:37 ` [PATCH V6 5/6] perf, x86: drain PEBS buffer during context switch Kan Liang
2015-04-09 16:37 ` [PATCH V6 6/6] perf, x86: enlarge PEBS buffer Kan Liang
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