perf lock contention: Add -G/--cgroup-filter option

The -G/--cgroup-filter is to limit lock contention collection on the
tasks in the specific cgroups only.

  $ sudo ./perf lock con -abt -G /user.slice/.../vte-spawn-52221fb8-b33f-4a52-b5c3-e35d1e6fc0e0.scope \
    ./perf bench sched messaging
  # Running 'sched/messaging' benchmark:
  # 20 sender and receiver processes per group
  # 10 groups == 400 processes run

       Total time: 0.174 [sec]
   contended   total wait     max wait     avg wait          pid   comm

           4    114.45 us     60.06 us     28.61 us       214847   sched-messaging
           2    111.40 us     60.84 us     55.70 us       214848   sched-messaging
           2    106.09 us     59.42 us     53.04 us       214837   sched-messaging
           1     81.70 us     81.70 us     81.70 us       214709   sched-messaging
          68     78.44 us      6.83 us      1.15 us       214633   sched-messaging
          69     73.71 us      2.69 us      1.07 us       214632   sched-messaging
           4     72.62 us     60.83 us     18.15 us       214850   sched-messaging
           2     71.75 us     67.60 us     35.88 us       214840   sched-messaging
           2     69.29 us     67.53 us     34.65 us       214804   sched-messaging
           2     69.00 us     68.23 us     34.50 us       214826   sched-messaging
  ...

Export cgroup__new() function as it's needed from outside.

Reviewed-by: Ian Rogers <irogers@google.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Hao Luo <haoluo@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Song Liu <song@kernel.org>
Cc: bpf@vger.kernel.org
Link: https://lore.kernel.org/r/20230906174903.346486-5-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 56 insertions, 0 deletions

diff --git a/tools/perf/builtin-lock.c b/tools/perf/builtin-lock.c
index 03d82f5a9afc..d4b22313e5fc 100644
--- a/tools/perf/builtin-lock.c
+++ b/tools/perf/builtin-lock.c
@@ -10,6 +10,7 @@
 #include "util/thread.h"
 #include "util/header.h"
 #include "util/target.h"
+#include "util/cgroup.h"
 #include "util/callchain.h"
 #include "util/lock-contention.h"
 #include "util/bpf_skel/lock_data.h"
@@ -1631,6 +1632,9 @@ static void lock_filter_finish(void)
 
 	zfree(&filters.syms);
 	filters.nr_syms = 0;
+
+	zfree(&filters.cgrps);
+	filters.nr_cgrps = 0;
 }
 
 static void sort_contention_result(void)
@@ -2488,6 +2492,56 @@ static int parse_output(const struct option *opt __maybe_unused, const char *str
 	return 0;
 }
 
+static bool add_lock_cgroup(char *name)
+{
+	u64 *tmp;
+	struct cgroup *cgrp;
+
+	cgrp = cgroup__new(name, /*do_open=*/false);
+	if (cgrp == NULL) {
+		pr_err("Failed to create cgroup: %s\n", name);
+		return false;
+	}
+
+	if (read_cgroup_id(cgrp) < 0) {
+		pr_err("Failed to read cgroup id for %s\n", name);
+		cgroup__put(cgrp);
+		return false;
+	}
+
+	tmp = realloc(filters.cgrps, (filters.nr_cgrps + 1) * sizeof(*filters.cgrps));
+	if (tmp == NULL) {
+		pr_err("Memory allocation failure\n");
+		return false;
+	}
+
+	tmp[filters.nr_cgrps++] = cgrp->id;
+	filters.cgrps = tmp;
+	cgroup__put(cgrp);
+	return true;
+}
+
+static int parse_cgroup_filter(const struct option *opt __maybe_unused, const char *str,
+			       int unset __maybe_unused)
+{
+	char *s, *tmp, *tok;
+	int ret = 0;
+
+	s = strdup(str);
+	if (s == NULL)
+		return -1;
+
+	for (tok = strtok_r(s, ", ", &tmp); tok; tok = strtok_r(NULL, ", ", &tmp)) {
+		if (!add_lock_cgroup(tok)) {
+			ret = -1;
+			break;
+		}
+	}
+
+	free(s);
+	return ret;
+}
+
 int cmd_lock(int argc, const char **argv)
 {
 	const struct option lock_options[] = {
@@ -2562,6 +2616,8 @@ int cmd_lock(int argc, const char **argv)
 	OPT_STRING_NOEMPTY('x', "field-separator", &symbol_conf.field_sep, "separator",
 		   "print result in CSV format with custom separator"),
 	OPT_BOOLEAN(0, "lock-cgroup", &show_lock_cgroups, "show lock stats by cgroup"),
+	OPT_CALLBACK('G', "cgroup-filter", NULL, "CGROUPS",
+		     "Filter specific cgroups", parse_cgroup_filter),
 	OPT_PARENT(lock_options)
 	};