[RFC PATCH 2/2] perf_events: add support for per-cpu per-cgroup monitoring

From: Stephane Eranian
Date: Tue Aug 31 2010 - 11:32:23 EST


This perf tool patch adds the ability to filter monitoring based on container
groups (cgroups) for both perf stat and perf record. The cgroup to monitor are
passed via a new -G option followed by a list of cgroups.

The cgroup filesystem has to be mounted. The tool will find it automatically,
open the right file and pass the descriptor to perf_events.

Example:
$ perf stat -a -e cycles:u -G test1 -- sleep 1
Performance counter stats for 'sleep 1':
9528573157 cycles test1 (scaled from 24.97%)
1.001702426 seconds time elapsed

The option is specified per event. It is possible to monitor different
cgroups in one run:

$ perf stat -a -e cycles:u,cycles:u -G test1,test2 -- sleep 1
Performance counter stats for 'sleep 1':
9528573157 cycles test1 (scaled from 24.97%)
9528574010 cycles test2 (scaled from 24.97%)
1.001702426 seconds time elapsed

Signed-off-by: Stephane Eranian <eranian@xxxxxxxxxx>
--

diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt
index 3ee27dc..0f9b8c8 100644
--- a/tools/perf/Documentation/perf-record.txt
+++ b/tools/perf/Documentation/perf-record.txt
@@ -116,6 +116,12 @@ Do not update the builid cache. This saves some overhead in situations
where the information in the perf.data file (which includes buildids)
is sufficient.

+-G name::
+--cgroup name::
+monitor only in the container called "name". This option is available only in per-cpu
+mode. The cgroup filesystem must be mounted. All threads belonging to container "name"
+are monitored when they run on the monitored CPUs.
+
SEE ALSO
--------
linkperf:perf-stat[1], linkperf:perf-list[1]
diff --git a/tools/perf/Documentation/perf-stat.txt b/tools/perf/Documentation/perf-stat.txt
index 4b3a2d4..4115f77 100644
--- a/tools/perf/Documentation/perf-stat.txt
+++ b/tools/perf/Documentation/perf-stat.txt
@@ -53,6 +53,11 @@ comma-sperated list with no space: 0,1. Ranges of CPUs are specified with -: 0-2
In per-thread mode, this option is ignored. The -a option is still necessary
to activate system-wide monitoring. Default is to count on all CPUs.

+-G name::
+--cgroup name::
+monitor only in the container called "name". This option is available only in per-cpu
+mode. The cgroup filesystem must be mounted. All threads belonging to container "name"
+are monitored when they run on the monitored CPUs.
EXAMPLES
--------

diff --git a/tools/perf/Makefile b/tools/perf/Makefile
index fe1e307..9f670e7 100644
--- a/tools/perf/Makefile
+++ b/tools/perf/Makefile
@@ -417,6 +417,7 @@ LIB_H += util/probe-finder.h
LIB_H += util/probe-event.h
LIB_H += util/pstack.h
LIB_H += util/cpumap.h
+LIB_H += util/cgroup.h

LIB_OBJS += $(OUTPUT)util/abspath.o
LIB_OBJS += $(OUTPUT)util/alias.o
@@ -464,6 +465,7 @@ LIB_OBJS += $(OUTPUT)util/hist.o
LIB_OBJS += $(OUTPUT)util/probe-event.o
LIB_OBJS += $(OUTPUT)util/util.o
LIB_OBJS += $(OUTPUT)util/cpumap.o
+LIB_OBJS += $(OUTPUT)util/cgroup.o

BUILTIN_OBJS += $(OUTPUT)builtin-annotate.o

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index ff77b80..604124e 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -22,6 +22,7 @@
#include "util/session.h"
#include "util/symbol.h"
#include "util/cpumap.h"
+#include "util/cgroup.h"

#include <unistd.h>
#include <sched.h>
@@ -286,6 +287,11 @@ static void create_counter(int counter, int cpu)
attr->sample_type |= PERF_SAMPLE_CPU;
}

+ if (cgroups[counter]) {
+ attr->cgroup = 1;
+ attr->cgroup_fd = cgroups_fd[counter];
+ }
+
attr->mmap = track;
attr->comm = track;
attr->inherit = !no_inherit;
@@ -828,6 +834,9 @@ static const struct option options[] = {
"don't sample"),
OPT_BOOLEAN('N', "no-buildid-cache", &no_buildid,
"do not update the buildid cache"),
+ OPT_CALLBACK('G', "cgroup", NULL, "name",
+ "monitor in cgroup name only",
+ parse_cgroups),
OPT_END()
};

@@ -851,6 +860,12 @@ int cmd_record(int argc, const char **argv, const char *prefix __used)
write_mode = WRITE_FORCE;
}

+ if (nr_cgroups && !system_wide)
+ usage_with_options(record_usage, options);
+
+ if (open_cgroups())
+ usage_with_options(record_usage, options);
+
symbol__init();
if (no_buildid)
disable_buildid_cache();
@@ -870,6 +885,7 @@ int cmd_record(int argc, const char **argv, const char *prefix __used)
usage_with_options(record_usage, options);
}
} else {
+ err = -ENOMEM;
all_tids=malloc(sizeof(pid_t));
if (!all_tids)
goto out_symbol_exit;
@@ -921,5 +937,6 @@ out_free_fd:
all_tids = NULL;
out_symbol_exit:
symbol__exit();
+ close_cgroups();
return err;
}
diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index a6b4d44..97c4284 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -47,6 +47,7 @@
#include "util/header.h"
#include "util/cpumap.h"
#include "util/thread.h"
+#include "util/cgroup.h"

#include <sys/prctl.h>
#include <math.h>
@@ -161,6 +162,11 @@ static int create_perf_stat_counter(int counter)
if (system_wide) {
int cpu;

+ if (cgroups[counter]) {
+ attr->cgroup = 1;
+ attr->cgroup_fd = cgroups_fd[counter];
+ }
+
for (cpu = 0; cpu < nr_cpus; cpu++) {
fd[cpu][counter][0] = sys_perf_event_open(attr,
-1, cpumap[cpu], -1, 0);
@@ -433,8 +439,13 @@ static void print_counter(int counter)
int scaled = event_scaled[counter];

if (scaled == -1) {
- fprintf(stderr, " %18s %-24s\n",
+ fprintf(stderr, " %18s %-24s",
"<not counted>", event_name(counter));
+
+ if (cgroups[counter])
+ fprintf(stderr, " %s", cgroups[counter]);
+
+ fprintf(stderr, "\n");
return;
}

@@ -445,6 +456,9 @@ static void print_counter(int counter)

print_noise(counter, avg);

+ if (cgroups[counter])
+ fprintf(stderr, " %s", cgroups[counter]);
+
if (scaled) {
double avg_enabled, avg_running;

@@ -454,7 +468,6 @@ static void print_counter(int counter)
fprintf(stderr, " (scaled from %.2f%%)",
100 * avg_running / avg_enabled);
}
-
fprintf(stderr, "\n");
}

@@ -545,6 +558,9 @@ static const struct option options[] = {
"print large numbers with thousands\' separators"),
OPT_STRING('C', "cpu", &cpu_list, "cpu",
"list of cpus to monitor in system-wide"),
+ OPT_CALLBACK('G', "cgroup", NULL, "name",
+ "monitor in cgroup name only",
+ parse_cgroups),
OPT_END()
};

@@ -562,6 +578,9 @@ int cmd_stat(int argc, const char **argv, const char *prefix __used)
if (run_count <= 0)
usage_with_options(stat_usage, options);

+ if (nr_cgroups && !system_wide)
+ usage_with_options(stat_usage, options);
+
/* Set attrs and nr_counters if no event is selected and !null_run */
if (!null_run && !nr_counters) {
memcpy(attrs, default_attrs, sizeof(default_attrs));
@@ -612,6 +631,9 @@ int cmd_stat(int argc, const char **argv, const char *prefix __used)
signal(SIGALRM, skip_signal);
signal(SIGABRT, skip_signal);

+ if (open_cgroups())
+ usage_with_options(stat_usage, options);
+
status = 0;
for (run_idx = 0; run_idx < run_count; run_idx++) {
if (run_count != 1 && verbose)
@@ -622,5 +644,7 @@ int cmd_stat(int argc, const char **argv, const char *prefix __used)
if (status != -1)
print_stat(argc, argv);

+ close_cgroups();
+
return status;
}
diff --git a/tools/perf/util/cgroup.c b/tools/perf/util/cgroup.c
new file mode 100644
index 0000000..eb76b31
--- /dev/null
+++ b/tools/perf/util/cgroup.c
@@ -0,0 +1,119 @@
+#include "util.h"
+#include "../perf.h"
+#include "parse-options.h"
+#include "parse-events.h" /* for nr_counters */
+#include "cgroup.h"
+#include "debugfs.h" /* MAX_PATH, STR() */
+
+char *cgroups[MAX_COUNTERS];
+int cgroups_fd[MAX_COUNTERS];
+int nr_cgroups;
+
+static char cgroup_mountpoint[MAX_PATH+1];
+
+static const char *cgroupfs_find_mountpoint(void)
+{
+ FILE *fp;
+ int found = 0;
+ char type[64];
+
+ fp = fopen("/proc/mounts", "r");
+ if (!fp)
+ return NULL;
+
+ while (fscanf(fp, "%*s %"
+ STR(MAX_PATH)
+ "s %99s %*s %*d %*d\n",
+ cgroup_mountpoint, type) == 2) {
+
+ if (!strcmp(type, "cgroup")) {
+ found = 1;
+ break;
+ }
+ }
+ fclose(fp);
+
+ if (found == 0)
+ return NULL;
+
+ return cgroup_mountpoint;
+}
+
+int open_cgroups(void)
+{
+ char path[MAX_PATH+1];
+ const char *mnt;
+ int i;
+
+ if (!nr_cgroups)
+ return 0;
+
+ mnt = cgroupfs_find_mountpoint();
+ if (!mnt)
+ return -1;
+
+ for (i = 0; i < nr_counters; i++) {
+
+ if (!cgroups[i])
+ continue;
+
+ snprintf(path, MAX_PATH, "%s/%s/perf_event.perf",
+ mnt, cgroups[i]);
+
+ cgroups_fd[i] = open(path, O_RDONLY);
+ if (cgroups_fd[i] == -1) {
+ fprintf(stderr, "no access to cgroup %s\n", path);
+ return -1;
+ }
+ }
+ return 0;
+}
+
+void close_cgroups(void)
+{
+ int i;
+
+ if (!nr_cgroups)
+ return;
+
+ for (i = 0; i < nr_counters; i++) {
+ if (!cgroups[i])
+ continue;
+ close(cgroups_fd[i]);
+ free(cgroups[i]);
+ cgroups[i] = NULL; /* catch errors */
+ }
+}
+
+int parse_cgroups(const struct option *opt __used, const char *str,
+ int unset __used)
+{
+ const char *p, *e, *eos = str + strlen(str);
+ int n = 0;
+ for (;;) {
+ p = strchr(str, ',');
+ e = p ? p : eos;
+
+ if (n == MAX_COUNTERS)
+ goto error;
+ /* allow empty cgroups, i.e., skip */
+ if (e - str) {
+ /* termination added */
+ cgroups[n] = strndup(str, e - str);
+ if (!cgroups[n])
+ goto error;
+ nr_cgroups++;
+ } else
+ cgroups[n] = NULL;
+ n++;
+ if (!p)
+ break;
+ str = p+1;
+ }
+ return 0;
+error:
+ while (--n >= 0)
+ if (cgroups[n])
+ free(cgroups[n]);
+ return -1;
+}
diff --git a/tools/perf/util/cgroup.h b/tools/perf/util/cgroup.h
new file mode 100644
index 0000000..99a7426
--- /dev/null
+++ b/tools/perf/util/cgroup.h
@@ -0,0 +1,14 @@
+#ifndef __CGROUP_H__
+#define __CGROUP_H__
+
+struct option;
+
+extern char *cgroups[MAX_COUNTERS];
+extern int cgroups_fd[MAX_COUNTERS];
+extern int nr_cgroups; /* number of explicit cgroups defined */
+
+extern int open_cgroups(void);
+extern void close_cgroups(void);
+extern int parse_cgroups(const struct option *opt, const char *str, int unset);
+
+#endif /* __CGROUP_H__ */
--
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