Messages in this thread | | | Date | Tue, 24 Jul 2012 18:15:07 +0200 | From | Robert Richter <> | Subject | Re: [PATCH 08/11] perf tool: precise mode requires exclude_guest |
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David,
On 24.07.12 08:20:19, David Ahern wrote: > On 7/23/12 12:13 PM, Arnaldo Carvalho de Melo wrote: > > Em Fri, Jul 20, 2012 at 05:25:53PM -0600, David Ahern escreveu: > >> PEBS cannot be used with guest mode. If user adds :p modifier set > >> exclude_guest as well. > > > > Is this something Intel specific? Or can someone think of an arch where > > this limitation wouldn't exist? > > Good point. So far precise_ip is used by arch/x86 only. I don't have an > AMD based server so I don't know if there is a conflict between > virtualization and IBS. Added Robert for advice.
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.
-Robert
-- Advanced Micro Devices, Inc. Operating System Research Center
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