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/openbmc/linux/tools/perf/arch/x86/util/ |
H A D | evsel.c | diff eb39bf325631f9ae185abd16281079b7b9858737 Tue Nov 02 00:31:12 CDT 2021 Ravi Bangoria <ravi.bangoria@amd.com> perf evsel: Don't set exclude_guest by default
Perf tool sets exclude_guest by default while calling perf_event_open(). Because IBS does not have filtering capability, it always gets rejected by IBS PMU driver and thus perf falls back to non-precise sampling. Fix it by not setting exclude_guest by default on AMD.
Before: $ sudo ./perf record -C 0 -vvv true |& grep precise precise_ip 3 decreasing precise_ip by one (2) precise_ip 2 decreasing precise_ip by one (1) precise_ip 1 decreasing precise_ip by one (0)
After: $ sudo ./perf record -C 0 -vvv true |& grep precise precise_ip 3 decreasing precise_ip by one (2) precise_ip 2
Committer notes:
Fixup init to zero for perf_env in older compilers:
arch/x86/util/evsel.c:15:26: error: missing field 'os_release' initializer [-Werror,-Wmissing-field-initializers] struct perf_env env = {0}; ^
Committer notes:
Namhyung remarked:
It'd be nice if it can cover explicit "-e cycles:pp" as well.
Ravi clarified:
For explicit :pp modifier, evsel->precise_max does not get set and thus perf does not try with different attr->precise_ip values while exclude_guest set. So no issue with explicit :pp:
$ sudo ./perf record -C 0 -e cycles:pp -vvv |& grep "precise_ip\|exclude_guest" precise_ip 2 exclude_guest 1 precise_ip 2 exclude_guest 1 switching off exclude_guest, exclude_host precise_ip 2 ^C
Also, with :P modifier, evsel->precise_max gets set but exclude_guest does not and thus :P also works fine:
$ sudo ./perf record -C 0 -e cycles:P -vvv |& grep "precise_ip\|exclude_guest" precise_ip 3 decreasing precise_ip by one (2) precise_ip 2 ^C
Reported-by: Kim Phillips <kim.phillips@amd.com> Signed-off-by: Ravi Bangoria <ravi.bangoria@amd.com> Acked-by: Namhyung Kim <namhyung@kernel.org> Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Ian Rogers <irogers@google.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Link: http://lore.kernel.org/lkml/20211103072112.32312-1-ravi.bangoria@amd.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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/openbmc/linux/tools/perf/util/ |
H A D | evsel.h | diff eb39bf325631f9ae185abd16281079b7b9858737 Tue Nov 02 00:31:12 CDT 2021 Ravi Bangoria <ravi.bangoria@amd.com> perf evsel: Don't set exclude_guest by default
Perf tool sets exclude_guest by default while calling perf_event_open(). Because IBS does not have filtering capability, it always gets rejected by IBS PMU driver and thus perf falls back to non-precise sampling. Fix it by not setting exclude_guest by default on AMD.
Before: $ sudo ./perf record -C 0 -vvv true |& grep precise precise_ip 3 decreasing precise_ip by one (2) precise_ip 2 decreasing precise_ip by one (1) precise_ip 1 decreasing precise_ip by one (0)
After: $ sudo ./perf record -C 0 -vvv true |& grep precise precise_ip 3 decreasing precise_ip by one (2) precise_ip 2
Committer notes:
Fixup init to zero for perf_env in older compilers:
arch/x86/util/evsel.c:15:26: error: missing field 'os_release' initializer [-Werror,-Wmissing-field-initializers] struct perf_env env = {0}; ^
Committer notes:
Namhyung remarked:
It'd be nice if it can cover explicit "-e cycles:pp" as well.
Ravi clarified:
For explicit :pp modifier, evsel->precise_max does not get set and thus perf does not try with different attr->precise_ip values while exclude_guest set. So no issue with explicit :pp:
$ sudo ./perf record -C 0 -e cycles:pp -vvv |& grep "precise_ip\|exclude_guest" precise_ip 2 exclude_guest 1 precise_ip 2 exclude_guest 1 switching off exclude_guest, exclude_host precise_ip 2 ^C
Also, with :P modifier, evsel->precise_max gets set but exclude_guest does not and thus :P also works fine:
$ sudo ./perf record -C 0 -e cycles:P -vvv |& grep "precise_ip\|exclude_guest" precise_ip 3 decreasing precise_ip by one (2) precise_ip 2 ^C
Reported-by: Kim Phillips <kim.phillips@amd.com> Signed-off-by: Ravi Bangoria <ravi.bangoria@amd.com> Acked-by: Namhyung Kim <namhyung@kernel.org> Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Ian Rogers <irogers@google.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Link: http://lore.kernel.org/lkml/20211103072112.32312-1-ravi.bangoria@amd.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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H A D | evsel.c | diff eb39bf325631f9ae185abd16281079b7b9858737 Tue Nov 02 00:31:12 CDT 2021 Ravi Bangoria <ravi.bangoria@amd.com> perf evsel: Don't set exclude_guest by default
Perf tool sets exclude_guest by default while calling perf_event_open(). Because IBS does not have filtering capability, it always gets rejected by IBS PMU driver and thus perf falls back to non-precise sampling. Fix it by not setting exclude_guest by default on AMD.
Before: $ sudo ./perf record -C 0 -vvv true |& grep precise precise_ip 3 decreasing precise_ip by one (2) precise_ip 2 decreasing precise_ip by one (1) precise_ip 1 decreasing precise_ip by one (0)
After: $ sudo ./perf record -C 0 -vvv true |& grep precise precise_ip 3 decreasing precise_ip by one (2) precise_ip 2
Committer notes:
Fixup init to zero for perf_env in older compilers:
arch/x86/util/evsel.c:15:26: error: missing field 'os_release' initializer [-Werror,-Wmissing-field-initializers] struct perf_env env = {0}; ^
Committer notes:
Namhyung remarked:
It'd be nice if it can cover explicit "-e cycles:pp" as well.
Ravi clarified:
For explicit :pp modifier, evsel->precise_max does not get set and thus perf does not try with different attr->precise_ip values while exclude_guest set. So no issue with explicit :pp:
$ sudo ./perf record -C 0 -e cycles:pp -vvv |& grep "precise_ip\|exclude_guest" precise_ip 2 exclude_guest 1 precise_ip 2 exclude_guest 1 switching off exclude_guest, exclude_host precise_ip 2 ^C
Also, with :P modifier, evsel->precise_max gets set but exclude_guest does not and thus :P also works fine:
$ sudo ./perf record -C 0 -e cycles:P -vvv |& grep "precise_ip\|exclude_guest" precise_ip 3 decreasing precise_ip by one (2) precise_ip 2 ^C
Reported-by: Kim Phillips <kim.phillips@amd.com> Signed-off-by: Ravi Bangoria <ravi.bangoria@amd.com> Acked-by: Namhyung Kim <namhyung@kernel.org> Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Ian Rogers <irogers@google.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Link: http://lore.kernel.org/lkml/20211103072112.32312-1-ravi.bangoria@amd.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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