perf offcpu: Parse process id separately

The current target code uses thread id for tracking tasks because
perf_events need to be opened for each task.  But we can use tgid in
BPF maps and check it easily.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Blake Jones <blakejones@google.com>
Cc: Hao Luo <haoluo@google.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Milian Wolff <milian.wolff@kdab.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: bpf@vger.kernel.org
Link: https://lore.kernel.org/r/20220811185456.194721-3-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/util/bpf_off_cpu.c b/tools/perf/util/bpf_off_cpu.c
index 7dbcb02..f7ee0c7 100644 (file)
--- a/tools/perf/util/bpf_off_cpu.c
+++ b/tools/perf/util/bpf_off_cpu.c
@@ -11,6 +11,7 @@
 #include "util/cpumap.h"
 #include "util/thread_map.h"
 #include "util/cgroup.h"
+#include "util/strlist.h"
 #include <bpf/bpf.h>
 
 #include "bpf_skel/off_cpu.skel.h"
@@ -125,6 +126,8 @@ int off_cpu_prepare(struct evlist *evlist, struct target *target,
 {
        int err, fd, i;
        int ncpus = 1, ntasks = 1, ncgrps = 1;
+       struct strlist *pid_slist = NULL;
+       struct str_node *pos;
 
        if (off_cpu_config(evlist) < 0) {
                pr_err("Failed to config off-cpu BPF event\n");
@@ -143,7 +146,26 @@ int off_cpu_prepare(struct evlist *evlist, struct target *target,
                bpf_map__set_max_entries(skel->maps.cpu_filter, ncpus);
        }
 
-       if (target__has_task(target)) {
+       if (target->pid) {
+               pid_slist = strlist__new(target->pid, NULL);
+               if (!pid_slist) {
+                       pr_err("Failed to create a strlist for pid\n");
+                       return -1;
+               }
+
+               ntasks = 0;
+               strlist__for_each_entry(pos, pid_slist) {
+                       char *end_ptr;
+                       int pid = strtol(pos->s, &end_ptr, 10);
+
+                       if (pid == INT_MIN || pid == INT_MAX ||
+                           (*end_ptr != '\0' && *end_ptr != ','))
+                               continue;
+
+                       ntasks++;
+               }
+               bpf_map__set_max_entries(skel->maps.task_filter, ntasks);
+       } else if (target__has_task(target)) {
                ntasks = perf_thread_map__nr(evlist->core.threads);
                bpf_map__set_max_entries(skel->maps.task_filter, ntasks);
        }
@@ -185,7 +207,26 @@ int off_cpu_prepare(struct evlist *evlist, struct target *target,
                }
        }
 
-       if (target__has_task(target)) {
+       if (target->pid) {
+               u8 val = 1;
+
+               skel->bss->has_task = 1;
+               skel->bss->uses_tgid = 1;
+               fd = bpf_map__fd(skel->maps.task_filter);
+
+               strlist__for_each_entry(pos, pid_slist) {
+                       char *end_ptr;
+                       u32 tgid;
+                       int pid = strtol(pos->s, &end_ptr, 10);
+
+                       if (pid == INT_MIN || pid == INT_MAX ||
+                           (*end_ptr != '\0' && *end_ptr != ','))
+                               continue;
+
+                       tgid = pid;
+                       bpf_map_update_elem(fd, &tgid, &val, BPF_ANY);
+               }
+       } else if (target__has_task(target)) {
                u32 pid;
                u8 val = 1;