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perf pmu: Unbreak perf record for arm/arm64 with events with explicit PMU

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Currently, perf record is broken on arm/arm64 systems when the PMU is
specified explicitly as part of the event, e.g.

$ ./perf record -e armv8_cortex_a53/cpu_cycles/u true

In such cases, perf record fails to open events unless
perf_event_paranoid is set to -1, even if the PMU in question supports
mode exclusion. Further, even when perf_event_paranoid is toggled, no
samples are recorded.

This is an unintended side effect of commit:

  e3ba76deef ("perf tools: Force uncore events to system wide monitoring)

... which assumes that if a PMU has an associated cpu_map, it is an
uncore PMU, and forces events for such PMUs to be system-wide.

This is not true for arm/arm64 systems, which can have heterogeneous
CPUs. To account for this, multiple CPU PMUs are exposed, each with a
"cpus" field under sysfs, which the perf tool parses into a cpu_map. ARM
PMUs do not have a "cpumask" file, and only have a "cpus" file. For the
gory details as to why, see commit:

 7e3fcffe95 ("perf pmu: Support alternative sysfs cpumask")

Given all of this, we can instead identify uncore PMUs by explicitly
checking for a "cpumask" file, and restore arm/arm64 PMU support back to
a working state. This patch does so, adding a new perf_pmu::is_uncore
field, and splitting the existing cpumask parsing so that it can be
reused.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Tested-by Will Deacon <will.deacon@arm.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: 4.12+ <stable@vger.kernel.org>
Fixes: e3ba76deef ("perf tools: Force uncore events to system wide monitoring)
Link: http://lkml.kernel.org/r/1507315102-5942-1-git-send-email-mark.rutland@arm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Mark Rutland
2017-10-06 19:38:22 +01:00
committed by Arnaldo Carvalho de Melo
parent e9516c0813
commit 66ec11919a
3 changed files with 54 additions and 26 deletions
Download Patch File Download Diff File Expand all files Collapse all files

9
tools/perf/util/parse-events.c
View File

@@ -309,10 +309,11 @@ static char *get_config_name(struct list_head *head_terms)
static struct perf_evsel *
__add_event(struct list_head *list, int *idx,
struct perf_event_attr *attr,
char *name, struct cpu_map *cpus,
char *name, struct perf_pmu *pmu,
struct list_head *config_terms, bool auto_merge_stats)
{
struct perf_evsel *evsel;
struct cpu_map *cpus = pmu ? pmu->cpus : NULL;
event_attr_init(attr);
@@ -323,7 +324,7 @@ __add_event(struct list_head *list, int *idx,
(*idx)++;
evsel->cpus = cpu_map__get(cpus);
evsel->own_cpus = cpu_map__get(cpus);
evsel->system_wide = !!cpus;
evsel->system_wide = pmu ? pmu->is_uncore : false;
evsel->auto_merge_stats = auto_merge_stats;
if (name)
@@ -1233,7 +1234,7 @@ static int __parse_events_add_pmu(struct parse_events_state *parse_state,
if (!head_config) {
attr.type = pmu->type;
evsel = __add_event(list, &parse_state->idx, &attr, NULL, pmu->cpus, NULL, auto_merge_stats);
evsel = __add_event(list, &parse_state->idx, &attr, NULL, pmu, NULL, auto_merge_stats);
return evsel ? 0 : -ENOMEM;
}
@@ -1254,7 +1255,7 @@ static int __parse_events_add_pmu(struct parse_events_state *parse_state,
return -EINVAL;
evsel = __add_event(list, &parse_state->idx, &attr,
get_config_name(head_config), pmu->cpus,
get_config_name(head_config), pmu,
&config_terms, auto_merge_stats);
if (evsel) {
evsel->unit = info.unit;