* [PATCH] perf trace: Handle task exit in BPF syscall summary
@ 2026-02-26 1:49 Namhyung Kim
2026-02-26 3:52 ` Ian Rogers
` (2 more replies)
0 siblings, 3 replies; 4+ messages in thread
From: Namhyung Kim @ 2026-02-26 1:49 UTC (permalink / raw)
To: Arnaldo Carvalho de Melo, Ian Rogers, James Clark
Cc: Jiri Olsa, Adrian Hunter, Peter Zijlstra, Ingo Molnar, LKML,
linux-perf-users, Howard Chu
Some system calls never return because it'd terminate the calling
thread. Let's hook the task exit path and update the duration of the
last syscall.
Before:
$ sudo perf trace -as --bpf-summary -- true |& grep exit
(nothing)
After:
$ sudo perf trace -as --bpf-summary -- true |& grep exit
exit_group 1 0 0.004 0.004 0.004 0.004 0.00%
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
tools/perf/util/bpf_skel/syscall_summary.bpf.c | 18 +++++++++++++++---
1 file changed, 15 insertions(+), 3 deletions(-)
diff --git a/tools/perf/util/bpf_skel/syscall_summary.bpf.c b/tools/perf/util/bpf_skel/syscall_summary.bpf.c
index 1bcd066a5199a476..4172f3c9fc483955 100644
--- a/tools/perf/util/bpf_skel/syscall_summary.bpf.c
+++ b/tools/perf/util/bpf_skel/syscall_summary.bpf.c
@@ -118,13 +118,11 @@ int sys_enter(u64 *ctx)
return 0;
}
-SEC("tp_btf/sys_exit")
-int sys_exit(u64 *ctx)
+static int do_exit(long ret)
{
int tid;
int key = 0;
u64 cgroup = 0;
- long ret = ctx[1]; /* return value of the syscall */
struct syscall_trace *st;
s64 delta;
@@ -150,4 +148,18 @@ int sys_exit(u64 *ctx)
return 0;
}
+SEC("tp_btf/sys_exit")
+int sys_exit(u64 *ctx)
+{
+ long ret = ctx[1]; /* return value of the syscall */
+
+ return do_exit(ret);
+}
+
+SEC("tp_btf/sched_process_exit")
+int process_exit(u64 *ctx)
+{
+ return do_exit(0);
+}
+
char _license[] SEC("license") = "GPL";
--
2.53.0.414.gf7e9f6c205-goog
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [PATCH] perf trace: Handle task exit in BPF syscall summary
2026-02-26 1:49 [PATCH] perf trace: Handle task exit in BPF syscall summary Namhyung Kim
@ 2026-02-26 3:52 ` Ian Rogers
2026-02-26 11:05 ` Howard Chu
2026-02-27 21:32 ` Namhyung Kim
2 siblings, 0 replies; 4+ messages in thread
From: Ian Rogers @ 2026-02-26 3:52 UTC (permalink / raw)
To: Namhyung Kim
Cc: Arnaldo Carvalho de Melo, James Clark, Jiri Olsa, Adrian Hunter,
Peter Zijlstra, Ingo Molnar, LKML, linux-perf-users, Howard Chu
On Wed, Feb 25, 2026 at 5:49 PM Namhyung Kim <namhyung@kernel.org> wrote:
>
> Some system calls never return because it'd terminate the calling
> thread. Let's hook the task exit path and update the duration of the
> last syscall.
>
> Before:
> $ sudo perf trace -as --bpf-summary -- true |& grep exit
> (nothing)
>
> After:
> $ sudo perf trace -as --bpf-summary -- true |& grep exit
> exit_group 1 0 0.004 0.004 0.004 0.004 0.00%
>
> Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Reviewed-by: Ian Rogers <irogers@google.com>
Thanks,
Ian
> ---
> tools/perf/util/bpf_skel/syscall_summary.bpf.c | 18 +++++++++++++++---
> 1 file changed, 15 insertions(+), 3 deletions(-)
>
> diff --git a/tools/perf/util/bpf_skel/syscall_summary.bpf.c b/tools/perf/util/bpf_skel/syscall_summary.bpf.c
> index 1bcd066a5199a476..4172f3c9fc483955 100644
> --- a/tools/perf/util/bpf_skel/syscall_summary.bpf.c
> +++ b/tools/perf/util/bpf_skel/syscall_summary.bpf.c
> @@ -118,13 +118,11 @@ int sys_enter(u64 *ctx)
> return 0;
> }
>
> -SEC("tp_btf/sys_exit")
> -int sys_exit(u64 *ctx)
> +static int do_exit(long ret)
> {
> int tid;
> int key = 0;
> u64 cgroup = 0;
> - long ret = ctx[1]; /* return value of the syscall */
> struct syscall_trace *st;
> s64 delta;
>
> @@ -150,4 +148,18 @@ int sys_exit(u64 *ctx)
> return 0;
> }
>
> +SEC("tp_btf/sys_exit")
> +int sys_exit(u64 *ctx)
> +{
> + long ret = ctx[1]; /* return value of the syscall */
> +
> + return do_exit(ret);
> +}
> +
> +SEC("tp_btf/sched_process_exit")
> +int process_exit(u64 *ctx)
> +{
> + return do_exit(0);
> +}
> +
> char _license[] SEC("license") = "GPL";
> --
> 2.53.0.414.gf7e9f6c205-goog
>
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH] perf trace: Handle task exit in BPF syscall summary
2026-02-26 1:49 [PATCH] perf trace: Handle task exit in BPF syscall summary Namhyung Kim
2026-02-26 3:52 ` Ian Rogers
@ 2026-02-26 11:05 ` Howard Chu
2026-02-27 21:32 ` Namhyung Kim
2 siblings, 0 replies; 4+ messages in thread
From: Howard Chu @ 2026-02-26 11:05 UTC (permalink / raw)
To: Namhyung Kim
Cc: Arnaldo Carvalho de Melo, Ian Rogers, James Clark, Jiri Olsa,
Adrian Hunter, Peter Zijlstra, Ingo Molnar, LKML,
linux-perf-users
Hi Namhyung,
On Wed, Feb 25, 2026 at 5:49 PM Namhyung Kim <namhyung@kernel.org> wrote:
>
> Some system calls never return because it'd terminate the calling
> thread. Let's hook the task exit path and update the duration of the
> last syscall.
>
> Before:
> $ sudo perf trace -as --bpf-summary -- true |& grep exit
> (nothing)
>
> After:
> $ sudo perf trace -as --bpf-summary -- true |& grep exit
> exit_group 1 0 0.004 0.004 0.004 0.004 0.00%
>
> Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Acked-by: Howard Chu <howardchu95@gmail.com>
Thanks,
Howard
> ---
> tools/perf/util/bpf_skel/syscall_summary.bpf.c | 18 +++++++++++++++---
> 1 file changed, 15 insertions(+), 3 deletions(-)
>
> diff --git a/tools/perf/util/bpf_skel/syscall_summary.bpf.c b/tools/perf/util/bpf_skel/syscall_summary.bpf.c
> index 1bcd066a5199a476..4172f3c9fc483955 100644
> --- a/tools/perf/util/bpf_skel/syscall_summary.bpf.c
> +++ b/tools/perf/util/bpf_skel/syscall_summary.bpf.c
> @@ -118,13 +118,11 @@ int sys_enter(u64 *ctx)
> return 0;
> }
>
> -SEC("tp_btf/sys_exit")
> -int sys_exit(u64 *ctx)
> +static int do_exit(long ret)
> {
> int tid;
> int key = 0;
> u64 cgroup = 0;
> - long ret = ctx[1]; /* return value of the syscall */
> struct syscall_trace *st;
> s64 delta;
>
> @@ -150,4 +148,18 @@ int sys_exit(u64 *ctx)
> return 0;
> }
>
> +SEC("tp_btf/sys_exit")
> +int sys_exit(u64 *ctx)
> +{
> + long ret = ctx[1]; /* return value of the syscall */
> +
> + return do_exit(ret);
> +}
> +
> +SEC("tp_btf/sched_process_exit")
> +int process_exit(u64 *ctx)
> +{
> + return do_exit(0);
> +}
> +
> char _license[] SEC("license") = "GPL";
> --
> 2.53.0.414.gf7e9f6c205-goog
>
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH] perf trace: Handle task exit in BPF syscall summary
2026-02-26 1:49 [PATCH] perf trace: Handle task exit in BPF syscall summary Namhyung Kim
2026-02-26 3:52 ` Ian Rogers
2026-02-26 11:05 ` Howard Chu
@ 2026-02-27 21:32 ` Namhyung Kim
2 siblings, 0 replies; 4+ messages in thread
From: Namhyung Kim @ 2026-02-27 21:32 UTC (permalink / raw)
To: Arnaldo Carvalho de Melo, Ian Rogers, James Clark, Namhyung Kim
Cc: Jiri Olsa, Adrian Hunter, Peter Zijlstra, Ingo Molnar, LKML,
linux-perf-users, Howard Chu
On Wed, 25 Feb 2026 17:49:55 -0800, Namhyung Kim wrote:
> Some system calls never return because it'd terminate the calling
> thread. Let's hook the task exit path and update the duration of the
> last syscall.
>
> Before:
> $ sudo perf trace -as --bpf-summary -- true |& grep exit
> (nothing)
>
> [...]
Applied to perf-tools-next, thanks!
Best regards,
Namhyung
^ permalink raw reply [flat|nested] 4+ messages in thread
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2026-02-26 1:49 [PATCH] perf trace: Handle task exit in BPF syscall summary Namhyung Kim
2026-02-26 3:52 ` Ian Rogers
2026-02-26 11:05 ` Howard Chu
2026-02-27 21:32 ` Namhyung Kim
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