Messages in this thread | | | Date | Tue, 24 Jul 2012 11:28:48 -0600 | From | David Ahern <> | Subject | Re: [PATCH 08/11] perf tool: precise mode requires exclude_guest |
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On 7/24/12 10:15 AM, Robert Richter wrote: > 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.
Ok, so with AMD precise_ip requires exclude_guest to be unset; for Intel we need it set.
So then we look at vendor_id in /proc/cpuinfo?
David
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