Messages in this thread | | | Date | Mon, 27 Feb 2012 11:00:04 -0700 | From | David Ahern <> | Subject | Re: [PATCH] perf tools: fix guest mode monitoring on AMD |
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On 2/27/12 10:52 AM, Stephane Eranian wrote: > On Mon, Feb 27, 2012 at 6:47 PM, David Ahern<dsahern@gmail.com> wrote: >> On 2/27/12 10:33 AM, Stephane Eranian wrote: >>> >>> Commit: >>> >>> 1aed267 perf kvm: Do guest-only counting by default >>> >>> introduced a bug on AMD systems whereby simple commands: >>> >>> $ perf stat ls >>> Performance counter stats for 'ls': >>> 0 cycles # 0.000 GHz >>> 0.003704596 seconds time elapsed >>> >>> would not count anything anymore. Same results for perf record. >>> >>> I tracked it down to guest mode exclusion being enabled >>> by default leading to attr->exclude_guest = 1. When >>> not operating under any sort of virtualization, this >>> causes the PMU not to count anything. >>> >>> The fix disables guest exclusion by default. >>> >>> Signed-off-by: Stephane Eranian<eranian@google.com> >>> --- >>> >>> diff --git a/tools/perf/util/util.c b/tools/perf/util/util.c >>> index 8109a90..c1017b3 100644 >>> --- a/tools/perf/util/util.c >>> +++ b/tools/perf/util/util.c >>> @@ -6,7 +6,7 @@ >>> * XXX We need to find a better place for these things... >>> */ >>> bool perf_host = true; >>> -bool perf_guest = false; >>> +bool perf_guest = true; >> >> >> This was recently reverted to false by >> c4a7dca92bbb9881a5d678720f1d0c2153499749 >> >> See: https://lkml.org/lkml/2012/2/8/234 >> > Yeah, but that causes simple commands such as "perf stat -e cycles ls" > to return 0 count. > > So either you get a segfault or you get zero count. There is something > else going on here...
agreed. Did you try reverting exclude_guest by default?
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