Messages in this thread | | | Date | Thu, 02 Aug 2012 10:06:58 -0600 | From | David Ahern <> | Subject | Re: [PATCH 08/11] perf tool: precise mode requires exclude_guest |
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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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