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perf
perf-evsel-don-t-set-exclude_guest-by-default.p...
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File perf-evsel-don-t-set-exclude_guest-by-default.patch of Package perf
From: Ravi Bangoria <ravi.bangoria@amd.com> Subject: perf evsel: Don't set exclude_guest by default Date: Tue Nov 2 11:01:12 2021 +0530 Git-commit: eb39bf325631f9ae185abd16281079b7b9858737 References: jsc#SLE-24578 (dependent patch) Signed-off-by: Tony Jones <tonyj@suse.de> 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> diff --git a/tools/perf/arch/x86/util/evsel.c b/tools/perf/arch/x86/util/evsel.c index 2f733cdc8dbb..ac2899a25b7a 100644 --- a/tools/perf/arch/x86/util/evsel.c +++ b/tools/perf/arch/x86/util/evsel.c @@ -1,8 +1,31 @@ // SPDX-License-Identifier: GPL-2.0 #include <stdio.h> +#include <stdlib.h> #include "util/evsel.h" +#include "util/env.h" +#include "linux/string.h" void arch_evsel__set_sample_weight(struct evsel *evsel) { evsel__set_sample_bit(evsel, WEIGHT_STRUCT); } + +void arch_evsel__fixup_new_cycles(struct perf_event_attr *attr) +{ + struct perf_env env = { .total_mem = 0, } ; + + if (!perf_env__cpuid(&env)) + return; + + /* + * On AMD, precise cycles event sampling internally uses IBS pmu. + * But IBS does not have filtering capabilities and perf by default + * sets exclude_guest = 1. This makes IBS pmu event init fail and + * thus perf ends up doing non-precise sampling. Avoid it by clearing + * exclude_guest. + */ + if (env.cpuid && strstarts(env.cpuid, "AuthenticAMD")) + attr->exclude_guest = 0; + + free(env.cpuid); +} diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c index 3cc1f8fcf15c..ec967fb8d7d9 100644 --- a/tools/perf/util/evsel.c +++ b/tools/perf/util/evsel.c @@ -294,7 +294,7 @@ static bool perf_event_can_profile_kernel(void) return perf_event_paranoid_check(1); } -struct evsel *evsel__new_cycles(bool precise, __u32 type, __u64 config) +struct evsel *evsel__new_cycles(bool precise __maybe_unused, __u32 type, __u64 config) { struct perf_event_attr attr = { .type = type, @@ -305,18 +305,16 @@ struct evsel *evsel__new_cycles(bool precise, __u32 type, __u64 config) event_attr_init(&attr); - if (!precise) - goto new_event; - /* * Now let the usual logic to set up the perf_event_attr defaults * to kick in when we return and before perf_evsel__open() is called. */ -new_event: evsel = evsel__new(&attr); if (evsel == NULL) goto out; + arch_evsel__fixup_new_cycles(&evsel->core.attr); + evsel->precise_max = true; /* use asprintf() because free(evsel) assumes name is allocated */ @@ -1063,6 +1061,10 @@ void __weak arch_evsel__set_sample_weight(struct evsel *evsel) evsel__set_sample_bit(evsel, WEIGHT); } +void __weak arch_evsel__fixup_new_cycles(struct perf_event_attr *attr __maybe_unused) +{ +} + /* * The enable_on_exec/disabled value strategy: * diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h index dcc87c2881b8..3ea687141afa 100644 --- a/tools/perf/util/evsel.h +++ b/tools/perf/util/evsel.h @@ -283,6 +283,7 @@ void __evsel__reset_sample_bit(struct evsel *evsel, enum perf_event_sample_forma void evsel__set_sample_id(struct evsel *evsel, bool use_sample_identifier); void arch_evsel__set_sample_weight(struct evsel *evsel); +void arch_evsel__fixup_new_cycles(struct perf_event_attr *attr); int evsel__set_filter(struct evsel *evsel, const char *filter); int evsel__append_tp_filter(struct evsel *evsel, const char *filter);
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