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Subject[PATCH 4/6] perf offcpu: Parse process id separately
Date
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>
---
tools/perf/util/bpf_off_cpu.c | 45 +++++++++++++++++++++++++++++++++--
1 file changed, 43 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/bpf_off_cpu.c b/tools/perf/util/bpf_off_cpu.c
index 7dbcb025da87..f7ee0c7a53f0 100644
--- 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;

--
2.37.0.rc0.161.g10f37bed90-goog
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