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perf pmu: Add support for PMU capabilities

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The PMU capabilities information, which is located at
/sys/bus/event_source/devices/<dev>/caps, is required by perf tool.  For
example, the max LBR information is required to stitch LBR call stack.

Add perf_pmu__caps_parse() to parse the PMU capabilities information.
The information is stored in a list.

The following patch will store the capabilities information in perf
header.

Committer notes:

Here's an example of such directories and its files in an i5 7th gen
machine:

  [root@seventh ~]# ls -lad /sys/bus/event_source/devices/*/caps
  drwxr-xr-x. 2 root root 0 Apr 14 13:33 /sys/bus/event_source/devices/cpu/caps
  drwxr-xr-x. 2 root root 0 Apr 14 13:33 /sys/bus/event_source/devices/intel_pt/caps
  [root@seventh ~]# ls -la /sys/bus/event_source/devices/intel_pt/caps
  total 0
  drwxr-xr-x. 2 root root    0 Apr 14 13:33 .
  drwxr-xr-x. 5 root root    0 Apr 14 13:12 ..
  -r--r--r--. 1 root root 4096 Apr 16 13:10 cr3_filtering
  -r--r--r--. 1 root root 4096 Apr 16 11:42 cycle_thresholds
  -r--r--r--. 1 root root 4096 Apr 16 13:10 ip_filtering
  -r--r--r--. 1 root root 4096 Apr 16 13:10 max_subleaf
  -r--r--r--. 1 root root 4096 Apr 14 13:33 mtc
  -r--r--r--. 1 root root 4096 Apr 14 13:33 mtc_periods
  -r--r--r--. 1 root root 4096 Apr 16 13:10 num_address_ranges
  -r--r--r--. 1 root root 4096 Apr 16 13:10 output_subsys
  -r--r--r--. 1 root root 4096 Apr 16 13:10 payloads_lip
  -r--r--r--. 1 root root 4096 Apr 16 13:10 power_event_trace
  -r--r--r--. 1 root root 4096 Apr 14 13:33 psb_cyc
  -r--r--r--. 1 root root 4096 Apr 14 13:33 psb_periods
  -r--r--r--. 1 root root 4096 Apr 16 13:10 ptwrite
  -r--r--r--. 1 root root 4096 Apr 16 13:10 single_range_output
  -r--r--r--. 1 root root 4096 Apr 16 12:03 topa_multiple_entries
  -r--r--r--. 1 root root 4096 Apr 16 13:10 topa_output
  [root@seventh ~]# cat /sys/bus/event_source/devices/intel_pt/caps/topa_output
  1
  [root@seventh ~]# cat /sys/bus/event_source/devices/intel_pt/caps/topa_multiple_entries
  1
  [root@seventh ~]# cat /sys/bus/event_source/devices/intel_pt/caps/mtc
  1
  [root@seventh ~]# cat /sys/bus/event_source/devices/intel_pt/caps/power_event_trace
  0
  [root@seventh ~]#

  [root@seventh ~]# ls -la /sys/bus/event_source/devices/cpu/caps/
  total 0
  drwxr-xr-x. 2 root root    0 Apr 14 13:33 .
  drwxr-xr-x. 6 root root    0 Apr 14 13:12 ..
  -r--r--r--. 1 root root 4096 Apr 16 13:10 branches
  -r--r--r--. 1 root root 4096 Apr 14 13:33 max_precise
  -r--r--r--. 1 root root 4096 Apr 16 13:10 pmu_name
  [root@seventh ~]# cat /sys/bus/event_source/devices/cpu/caps/max_precise
  3
  [root@seventh ~]# cat /sys/bus/event_source/devices/cpu/caps/branches
  32
  [root@seventh ~]# cat /sys/bus/event_source/devices/cpu/caps/pmu_name
  skylake
  [root@seventh ~]#

Wow, first time I've heard about
/sys/bus/event_source/devices/cpu/caps/max_precise, I think I'll use it!
:-)

Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexey Budankov <alexey.budankov@linux.intel.com>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Pavel Gerasimov <pavel.gerasimov@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Vitaly Slobodskoy <vitaly.slobodskoy@intel.com>
Link: http://lore.kernel.org/lkml/20200319202517.23423-2-kan.liang@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Kan Liang 2020-03-19 13:25:01 -07:00 committed by Arnaldo Carvalho de Melo
parent f8ff18be1f
commit 9fbc61f832
2 changed files with 91 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

82
tools/perf/util/pmu.c
View File

@ -850,6 +850,7 @@ static struct perf_pmu *pmu_lookup(const char *name)
INIT_LIST_HEAD(&pmu->format);
INIT_LIST_HEAD(&pmu->aliases);
INIT_LIST_HEAD(&pmu->caps);
list_splice(&format, &pmu->format);
list_splice(&aliases, &pmu->aliases);
list_add_tail(&pmu->list, &pmus);
@ -1594,3 +1595,84 @@ int perf_pmu__scan_file(struct perf_pmu *pmu, const char *name, const char *fmt,
va_end(args);
return ret;
}
static int perf_pmu__new_caps(struct list_head *list, char *name, char *value)
{
struct perf_pmu_caps *caps = zalloc(sizeof(*caps));
if (!caps)
return -ENOMEM;
caps->name = strdup(name);
if (!caps->name)
goto free_caps;
caps->value = strndup(value, strlen(value) - 1);
if (!caps->value)
goto free_name;
list_add_tail(&caps->list, list);
return 0;
free_name:
zfree(caps->name);
free_caps:
free(caps);
return -ENOMEM;
}
/*
* Reading/parsing the given pmu capabilities, which should be located at:
* /sys/bus/event_source/devices/<dev>/caps as sysfs group attributes.
* Return the number of capabilities
*/
int perf_pmu__caps_parse(struct perf_pmu *pmu)
{
struct stat st;
char caps_path[PATH_MAX];
const char *sysfs = sysfs__mountpoint();
DIR *caps_dir;
struct dirent *evt_ent;
int nr_caps = 0;
if (!sysfs)
return -1;
snprintf(caps_path, PATH_MAX,
"%s" EVENT_SOURCE_DEVICE_PATH "%s/caps", sysfs, pmu->name);
if (stat(caps_path, &st) < 0)
return 0; /* no error if caps does not exist */
caps_dir = opendir(caps_path);
if (!caps_dir)
return -EINVAL;
while ((evt_ent = readdir(caps_dir)) != NULL) {
char path[PATH_MAX + NAME_MAX + 1];
char *name = evt_ent->d_name;
char value[128];
FILE *file;
if (!strcmp(name, ".") || !strcmp(name, ".."))
continue;
snprintf(path, sizeof(path), "%s/%s", caps_path, name);
file = fopen(path, "r");
if (!file)
continue;
if (!fgets(value, sizeof(value), file) ||
(perf_pmu__new_caps(&pmu->caps, name, value) < 0)) {
fclose(file);
continue;
}
nr_caps++;
fclose(file);
}
closedir(caps_dir);
return nr_caps;
}

9
tools/perf/util/pmu.h
View File

@ -22,6 +22,12 @@ enum {
struct perf_event_attr;
struct perf_pmu_caps {
char *name;
char *value;
struct list_head list;
};
struct perf_pmu {
char *name;
__u32 type;
@ -33,6 +39,7 @@ struct perf_pmu {
struct perf_cpu_map *cpus;
struct list_head format; /* HEAD struct perf_pmu_format -> list */
struct list_head aliases; /* HEAD struct perf_pmu_alias -> list */
struct list_head caps; /* HEAD struct perf_pmu_caps -> list */
struct list_head list; /* ELEM */
};
@ -107,4 +114,6 @@ bool pmu_uncore_alias_match(const char *pmu_name, const char *name);
int perf_pmu__convert_scale(const char *scale, char **end, double *sval);
int perf_pmu__caps_parse(struct perf_pmu *pmu);
#endif /* __PMU_H */