linux-kernel - Re: [PATCH 08/11] perf tool: precise mode requires exclude

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Date:	Thu, 02 Aug 2012 10:06:58 -0600
From:	David Ahern <dsahern@...il.com>
To:	Gleb Natapov <gleb@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>
CC:	Robert Richter <robert.richter@....com>,
	Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
	linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...nel.org>,
	Jiri Olsa <jolsa@...hat.com>,
	Namhyung Kim <namhyung@...nel.org>,
	Frederic Weisbecker <fweisbec@...il.com>
Subject: Re: [PATCH 08/11] perf tool: precise mode requires exclude_guest

Hi Peter:

On 7/25/12 11:50 PM, Gleb Natapov wrote:
> On Wed, Jul 25, 2012 at 10:35:46PM +0200, Peter Zijlstra wrote:
>> On Tue, 2012-07-24 at 18:15 +0200, Robert Richter wrote:
>>> thanks for this hint.
>>>
>>> On AMD cpus precise_ip maps to IBS, which does not support hardware
>>> options as perfctrs do. Thus, following attr flags are not supported:
>>>
>>>   exclude_user, exclude_kernel, exclude_host, exclude_guest
>>>
>>> Counting in guest mode is possible with IBS, but not the exclusion of
>>> a certain mode. If precise_ip counting is enabled on AMD we may not
>>> set the exclude_guest flag.
>>
>> IIRC we have SVM enter/exit hooks in kvm/perf already, we could use
>> those to implement exclude_guest for IBS.
>>
>> Now I've been trying to find the patches that introduced that, but I'm
>> failing horridly. Gleb, got us a pointer here?
> The commit is 144d31e6, but it introduces hook that is used on VMX only.
> SVM does not need it to implement guest/host only counters since it
> has HW support for that in the PMU.

Any updates?

David

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