* [PATCH v8 01/10] perf record --off-cpu: Add --off-cpu-thresh option
2024-11-13 0:28 [PATCH v8 00/10] perf record --off-cpu: Dump off-cpu samples directly Howard Chu
@ 2024-11-13 0:28 ` Howard Chu
2024-11-18 21:09 ` Namhyung Kim
2024-11-13 0:28 ` [PATCH v8 02/10] perf evsel: Expose evsel__is_offcpu_event() for future use Howard Chu
` (9 subsequent siblings)
10 siblings, 1 reply; 18+ messages in thread
From: Howard Chu @ 2024-11-13 0:28 UTC (permalink / raw)
To: acme, peterz
Cc: namhyung, irogers, mingo, jolsa, adrian.hunter, kan.liang,
linux-perf-users, linux-kernel, Howard Chu, Alexander Shishkin,
James Clark, Mark Rutland, Arnaldo Carvalho de Melo
Specify the threshold for dumping offcpu samples with --off-cpu-thresh,
the unit is us (microsecond). Default value is 500000us (500ms, 0.5s).
Suggested-by: Ian Rogers <irogers@google.com>
Reviewed-by: Ian Rogers <irogers@google.com>
Signed-off-by: Howard Chu <howardchu95@gmail.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20241108204137.2444151-2-howardchu95@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/builtin-record.c | 26 ++++++++++++++++++++++++++
tools/perf/util/off_cpu.h | 1 +
tools/perf/util/record.h | 1 +
3 files changed, 28 insertions(+)
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index f83252472921..c069000efe5c 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -3149,6 +3149,28 @@ static int record__parse_mmap_pages(const struct option *opt,
return ret;
}
+static int record__parse_off_cpu_thresh(const struct option *opt,
+ const char *str,
+ int unset __maybe_unused)
+{
+ struct record_opts *opts = opt->value;
+ char *endptr;
+ u64 off_cpu_thresh_us;
+
+ if (!str)
+ return -EINVAL;
+
+ off_cpu_thresh_us = strtoull(str, &endptr, 10);
+
+ /* threshold isn't string "0", yet strtoull() returns 0, parsing failed */
+ if (*endptr || (off_cpu_thresh_us == 0 && strcmp(str, "0")))
+ return -EINVAL;
+ else
+ opts->off_cpu_thresh_us = off_cpu_thresh_us;
+
+ return 0;
+}
+
void __weak arch__add_leaf_frame_record_opts(struct record_opts *opts __maybe_unused)
{
}
@@ -3342,6 +3364,7 @@ static struct record record = {
.ctl_fd = -1,
.ctl_fd_ack = -1,
.synth = PERF_SYNTH_ALL,
+ .off_cpu_thresh_us = OFFCPU_THRESH,
},
};
@@ -3564,6 +3587,9 @@ static struct option __record_options[] = {
OPT_BOOLEAN(0, "off-cpu", &record.off_cpu, "Enable off-cpu analysis"),
OPT_STRING(0, "setup-filter", &record.filter_action, "pin|unpin",
"BPF filter action"),
+ OPT_CALLBACK(0, "off-cpu-thresh", &record.opts, "us",
+ "Dump off-cpu samples if off-cpu time reaches this threshold. The unit is microsecond (default: 500000)",
+ record__parse_off_cpu_thresh),
OPT_END()
};
diff --git a/tools/perf/util/off_cpu.h b/tools/perf/util/off_cpu.h
index 2dd67c60f211..c6edc0f7c40d 100644
--- a/tools/perf/util/off_cpu.h
+++ b/tools/perf/util/off_cpu.h
@@ -16,6 +16,7 @@ struct record_opts;
PERF_SAMPLE_PERIOD | PERF_SAMPLE_CALLCHAIN | \
PERF_SAMPLE_CGROUP)
+#define OFFCPU_THRESH 500000ull
#ifdef HAVE_BPF_SKEL
int off_cpu_prepare(struct evlist *evlist, struct target *target,
diff --git a/tools/perf/util/record.h b/tools/perf/util/record.h
index a6566134e09e..2ca74add26c0 100644
--- a/tools/perf/util/record.h
+++ b/tools/perf/util/record.h
@@ -79,6 +79,7 @@ struct record_opts {
int synth;
int threads_spec;
const char *threads_user_spec;
+ u64 off_cpu_thresh_us;
};
extern const char * const *record_usage;
--
2.43.0
^ permalink raw reply related [flat|nested] 18+ messages in thread* Re: [PATCH v8 01/10] perf record --off-cpu: Add --off-cpu-thresh option
2024-11-13 0:28 ` [PATCH v8 01/10] perf record --off-cpu: Add --off-cpu-thresh option Howard Chu
@ 2024-11-18 21:09 ` Namhyung Kim
2024-11-18 23:03 ` Howard Chu
0 siblings, 1 reply; 18+ messages in thread
From: Namhyung Kim @ 2024-11-18 21:09 UTC (permalink / raw)
To: Howard Chu
Cc: acme, peterz, irogers, mingo, jolsa, adrian.hunter, kan.liang,
linux-perf-users, linux-kernel, Alexander Shishkin, James Clark,
Mark Rutland, Arnaldo Carvalho de Melo
Hello Howard,
On Tue, Nov 12, 2024 at 04:28:09PM -0800, Howard Chu wrote:
> Specify the threshold for dumping offcpu samples with --off-cpu-thresh,
> the unit is us (microsecond). Default value is 500000us (500ms, 0.5s).
I think it's better to add an option after you implemented the feature.
Before that you may hardcode the threshold if necessary.
Also it'd be a good practice to add an example for the option in the
commit message.
>
> Suggested-by: Ian Rogers <irogers@google.com>
> Reviewed-by: Ian Rogers <irogers@google.com>
> Signed-off-by: Howard Chu <howardchu95@gmail.com>
> Cc: Adrian Hunter <adrian.hunter@intel.com>
> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: James Clark <james.clark@linaro.org>
> Cc: Jiri Olsa <jolsa@kernel.org>
> Cc: Kan Liang <kan.liang@linux.intel.com>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: Namhyung Kim <namhyung@kernel.org>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Link: https://lore.kernel.org/r/20241108204137.2444151-2-howardchu95@gmail.com
> Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
> ---
> tools/perf/builtin-record.c | 26 ++++++++++++++++++++++++++
> tools/perf/util/off_cpu.h | 1 +
> tools/perf/util/record.h | 1 +
Please update the documentation if you add a new option.
Thanks,
Namhyung
> 3 files changed, 28 insertions(+)
>
> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
> index f83252472921..c069000efe5c 100644
> --- a/tools/perf/builtin-record.c
> +++ b/tools/perf/builtin-record.c
> @@ -3149,6 +3149,28 @@ static int record__parse_mmap_pages(const struct option *opt,
> return ret;
> }
>
> +static int record__parse_off_cpu_thresh(const struct option *opt,
> + const char *str,
> + int unset __maybe_unused)
> +{
> + struct record_opts *opts = opt->value;
> + char *endptr;
> + u64 off_cpu_thresh_us;
> +
> + if (!str)
> + return -EINVAL;
> +
> + off_cpu_thresh_us = strtoull(str, &endptr, 10);
> +
> + /* threshold isn't string "0", yet strtoull() returns 0, parsing failed */
> + if (*endptr || (off_cpu_thresh_us == 0 && strcmp(str, "0")))
> + return -EINVAL;
> + else
> + opts->off_cpu_thresh_us = off_cpu_thresh_us;
> +
> + return 0;
> +}
> +
> void __weak arch__add_leaf_frame_record_opts(struct record_opts *opts __maybe_unused)
> {
> }
> @@ -3342,6 +3364,7 @@ static struct record record = {
> .ctl_fd = -1,
> .ctl_fd_ack = -1,
> .synth = PERF_SYNTH_ALL,
> + .off_cpu_thresh_us = OFFCPU_THRESH,
> },
> };
>
> @@ -3564,6 +3587,9 @@ static struct option __record_options[] = {
> OPT_BOOLEAN(0, "off-cpu", &record.off_cpu, "Enable off-cpu analysis"),
> OPT_STRING(0, "setup-filter", &record.filter_action, "pin|unpin",
> "BPF filter action"),
> + OPT_CALLBACK(0, "off-cpu-thresh", &record.opts, "us",
> + "Dump off-cpu samples if off-cpu time reaches this threshold. The unit is microsecond (default: 500000)",
> + record__parse_off_cpu_thresh),
> OPT_END()
> };
>
> diff --git a/tools/perf/util/off_cpu.h b/tools/perf/util/off_cpu.h
> index 2dd67c60f211..c6edc0f7c40d 100644
> --- a/tools/perf/util/off_cpu.h
> +++ b/tools/perf/util/off_cpu.h
> @@ -16,6 +16,7 @@ struct record_opts;
> PERF_SAMPLE_PERIOD | PERF_SAMPLE_CALLCHAIN | \
> PERF_SAMPLE_CGROUP)
>
> +#define OFFCPU_THRESH 500000ull
>
> #ifdef HAVE_BPF_SKEL
> int off_cpu_prepare(struct evlist *evlist, struct target *target,
> diff --git a/tools/perf/util/record.h b/tools/perf/util/record.h
> index a6566134e09e..2ca74add26c0 100644
> --- a/tools/perf/util/record.h
> +++ b/tools/perf/util/record.h
> @@ -79,6 +79,7 @@ struct record_opts {
> int synth;
> int threads_spec;
> const char *threads_user_spec;
> + u64 off_cpu_thresh_us;
> };
>
> extern const char * const *record_usage;
> --
> 2.43.0
>
^ permalink raw reply [flat|nested] 18+ messages in thread* Re: [PATCH v8 01/10] perf record --off-cpu: Add --off-cpu-thresh option
2024-11-18 21:09 ` Namhyung Kim
@ 2024-11-18 23:03 ` Howard Chu
0 siblings, 0 replies; 18+ messages in thread
From: Howard Chu @ 2024-11-18 23:03 UTC (permalink / raw)
To: Namhyung Kim
Cc: acme, peterz, irogers, mingo, jolsa, adrian.hunter, kan.liang,
linux-perf-users, linux-kernel, Alexander Shishkin, James Clark,
Mark Rutland, Arnaldo Carvalho de Melo
Hello Namhyung,
On Mon, Nov 18, 2024 at 1:09 PM Namhyung Kim <namhyung@kernel.org> wrote:
>
> Hello Howard,
>
> On Tue, Nov 12, 2024 at 04:28:09PM -0800, Howard Chu wrote:
> > Specify the threshold for dumping offcpu samples with --off-cpu-thresh,
> > the unit is us (microsecond). Default value is 500000us (500ms, 0.5s).
>
> I think it's better to add an option after you implemented the feature.
> Before that you may hardcode the threshold if necessary.
>
> Also it'd be a good practice to add an example for the option in the
> commit message.
Sure.
>
> >
> > Suggested-by: Ian Rogers <irogers@google.com>
> > Reviewed-by: Ian Rogers <irogers@google.com>
> > Signed-off-by: Howard Chu <howardchu95@gmail.com>
> > Cc: Adrian Hunter <adrian.hunter@intel.com>
> > Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
> > Cc: Ingo Molnar <mingo@redhat.com>
> > Cc: James Clark <james.clark@linaro.org>
> > Cc: Jiri Olsa <jolsa@kernel.org>
> > Cc: Kan Liang <kan.liang@linux.intel.com>
> > Cc: Mark Rutland <mark.rutland@arm.com>
> > Cc: Namhyung Kim <namhyung@kernel.org>
> > Cc: Peter Zijlstra <peterz@infradead.org>
> > Link: https://lore.kernel.org/r/20241108204137.2444151-2-howardchu95@gmail.com
> > Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
> > ---
> > tools/perf/builtin-record.c | 26 ++++++++++++++++++++++++++
> > tools/perf/util/off_cpu.h | 1 +
> > tools/perf/util/record.h | 1 +
>
> Please update the documentation if you add a new option.
Ok sure.
Thanks,
Howard
>
> Thanks,
> Namhyung
>
>
> > 3 files changed, 28 insertions(+)
> >
> > diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
> > index f83252472921..c069000efe5c 100644
> > --- a/tools/perf/builtin-record.c
> > +++ b/tools/perf/builtin-record.c
> > @@ -3149,6 +3149,28 @@ static int record__parse_mmap_pages(const struct option *opt,
> > return ret;
> > }
> >
> > +static int record__parse_off_cpu_thresh(const struct option *opt,
> > + const char *str,
> > + int unset __maybe_unused)
> > +{
> > + struct record_opts *opts = opt->value;
> > + char *endptr;
> > + u64 off_cpu_thresh_us;
> > +
> > + if (!str)
> > + return -EINVAL;
> > +
> > + off_cpu_thresh_us = strtoull(str, &endptr, 10);
> > +
> > + /* threshold isn't string "0", yet strtoull() returns 0, parsing failed */
> > + if (*endptr || (off_cpu_thresh_us == 0 && strcmp(str, "0")))
> > + return -EINVAL;
> > + else
> > + opts->off_cpu_thresh_us = off_cpu_thresh_us;
> > +
> > + return 0;
> > +}
> > +
> > void __weak arch__add_leaf_frame_record_opts(struct record_opts *opts __maybe_unused)
> > {
> > }
> > @@ -3342,6 +3364,7 @@ static struct record record = {
> > .ctl_fd = -1,
> > .ctl_fd_ack = -1,
> > .synth = PERF_SYNTH_ALL,
> > + .off_cpu_thresh_us = OFFCPU_THRESH,
> > },
> > };
> >
> > @@ -3564,6 +3587,9 @@ static struct option __record_options[] = {
> > OPT_BOOLEAN(0, "off-cpu", &record.off_cpu, "Enable off-cpu analysis"),
> > OPT_STRING(0, "setup-filter", &record.filter_action, "pin|unpin",
> > "BPF filter action"),
> > + OPT_CALLBACK(0, "off-cpu-thresh", &record.opts, "us",
> > + "Dump off-cpu samples if off-cpu time reaches this threshold. The unit is microsecond (default: 500000)",
> > + record__parse_off_cpu_thresh),
> > OPT_END()
> > };
> >
> > diff --git a/tools/perf/util/off_cpu.h b/tools/perf/util/off_cpu.h
> > index 2dd67c60f211..c6edc0f7c40d 100644
> > --- a/tools/perf/util/off_cpu.h
> > +++ b/tools/perf/util/off_cpu.h
> > @@ -16,6 +16,7 @@ struct record_opts;
> > PERF_SAMPLE_PERIOD | PERF_SAMPLE_CALLCHAIN | \
> > PERF_SAMPLE_CGROUP)
> >
> > +#define OFFCPU_THRESH 500000ull
> >
> > #ifdef HAVE_BPF_SKEL
> > int off_cpu_prepare(struct evlist *evlist, struct target *target,
> > diff --git a/tools/perf/util/record.h b/tools/perf/util/record.h
> > index a6566134e09e..2ca74add26c0 100644
> > --- a/tools/perf/util/record.h
> > +++ b/tools/perf/util/record.h
> > @@ -79,6 +79,7 @@ struct record_opts {
> > int synth;
> > int threads_spec;
> > const char *threads_user_spec;
> > + u64 off_cpu_thresh_us;
> > };
> >
> > extern const char * const *record_usage;
> > --
> > 2.43.0
> >
^ permalink raw reply [flat|nested] 18+ messages in thread
* [PATCH v8 02/10] perf evsel: Expose evsel__is_offcpu_event() for future use
2024-11-13 0:28 [PATCH v8 00/10] perf record --off-cpu: Dump off-cpu samples directly Howard Chu
2024-11-13 0:28 ` [PATCH v8 01/10] perf record --off-cpu: Add --off-cpu-thresh option Howard Chu
@ 2024-11-13 0:28 ` Howard Chu
2024-11-13 0:28 ` [PATCH v8 03/10] perf record --off-cpu: Parse off-cpu event Howard Chu
` (8 subsequent siblings)
10 siblings, 0 replies; 18+ messages in thread
From: Howard Chu @ 2024-11-13 0:28 UTC (permalink / raw)
To: acme, peterz
Cc: namhyung, irogers, mingo, jolsa, adrian.hunter, kan.liang,
linux-perf-users, linux-kernel, Howard Chu, Alexander Shishkin,
James Clark, Mark Rutland, Arnaldo Carvalho de Melo
Expose evsel__is_offcpu_event() so it can be used in
off_cpu_config(), evsel__parse_sample(), and perf script.
Reviewed-by: Ian Rogers <irogers@google.com>
Signed-off-by: Howard Chu <howardchu95@gmail.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20241108204137.2444151-3-howardchu95@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/util/evsel.c | 2 +-
tools/perf/util/evsel.h | 2 ++
2 files changed, 3 insertions(+), 1 deletion(-)
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index f745723d486b..8d0308f62484 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -1194,7 +1194,7 @@ static void evsel__set_default_freq_period(struct record_opts *opts,
}
}
-static bool evsel__is_offcpu_event(struct evsel *evsel)
+bool evsel__is_offcpu_event(struct evsel *evsel)
{
return evsel__is_bpf_output(evsel) && evsel__name_is(evsel, OFFCPU_EVENT);
}
diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
index 04934a7af174..7f68004507d8 100644
--- a/tools/perf/util/evsel.h
+++ b/tools/perf/util/evsel.h
@@ -554,4 +554,6 @@ u64 evsel__bitfield_swap_branch_flags(u64 value);
void evsel__set_config_if_unset(struct perf_pmu *pmu, struct evsel *evsel,
const char *config_name, u64 val);
+bool evsel__is_offcpu_event(struct evsel *evsel);
+
#endif /* __PERF_EVSEL_H */
--
2.43.0
^ permalink raw reply related [flat|nested] 18+ messages in thread* [PATCH v8 03/10] perf record --off-cpu: Parse off-cpu event
2024-11-13 0:28 [PATCH v8 00/10] perf record --off-cpu: Dump off-cpu samples directly Howard Chu
2024-11-13 0:28 ` [PATCH v8 01/10] perf record --off-cpu: Add --off-cpu-thresh option Howard Chu
2024-11-13 0:28 ` [PATCH v8 02/10] perf evsel: Expose evsel__is_offcpu_event() for future use Howard Chu
@ 2024-11-13 0:28 ` Howard Chu
2024-11-18 21:17 ` Namhyung Kim
2024-11-13 0:28 ` [PATCH v8 04/10] perf record --off-cpu: Preparation of off-cpu BPF program Howard Chu
` (7 subsequent siblings)
10 siblings, 1 reply; 18+ messages in thread
From: Howard Chu @ 2024-11-13 0:28 UTC (permalink / raw)
To: acme, peterz
Cc: namhyung, irogers, mingo, jolsa, adrian.hunter, kan.liang,
linux-perf-users, linux-kernel, Howard Chu, Alexander Shishkin,
James Clark, Mark Rutland, Arnaldo Carvalho de Melo
Parse the off-cpu event using parse_event(), as bpf-output.
no-inherit should be set to 1, here's the reason:
We update the BPF perf_event map for direct off-cpu sample dumping (in
following patches), it executes as follows:
bpf_map_update_value()
bpf_fd_array_map_update_elem()
perf_event_fd_array_get_ptr()
perf_event_read_local()
In perf_event_read_local(), there is:
int perf_event_read_local(struct perf_event *event, u64 *value,
u64 *enabled, u64 *running)
{
...
/*
* It must not be an event with inherit set, we cannot read
* all child counters from atomic context.
*/
if (event->attr.inherit) {
ret = -EOPNOTSUPP;
goto out;
}
Which means no-inherit has to be true for updating the BPF perf_event
map.
Moreover, for bpf-output events, we primarily want a system-wide event
instead of a per-task event.
The reason is that in BPF's bpf_perf_event_output(), BPF uses the CPU
index to retrieve the perf_event file descriptor it outputs to.
Making a bpf-output event system-wide naturally satisfies this
requirement by mapping CPU appropriately.
Suggested-by: Namhyung Kim <namhyung@kernel.org>
Reviewed-by: Ian Rogers <irogers@google.com>
Signed-off-by: Howard Chu <howardchu95@gmail.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20241108204137.2444151-4-howardchu95@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/util/bpf_off_cpu.c | 33 +++++++++++----------------------
1 file changed, 11 insertions(+), 22 deletions(-)
diff --git a/tools/perf/util/bpf_off_cpu.c b/tools/perf/util/bpf_off_cpu.c
index a590a8ac1f9d..558c5e5c2dc3 100644
--- a/tools/perf/util/bpf_off_cpu.c
+++ b/tools/perf/util/bpf_off_cpu.c
@@ -38,32 +38,21 @@ union off_cpu_data {
static int off_cpu_config(struct evlist *evlist)
{
+ char off_cpu_event[64];
struct evsel *evsel;
- struct perf_event_attr attr = {
- .type = PERF_TYPE_SOFTWARE,
- .config = PERF_COUNT_SW_BPF_OUTPUT,
- .size = sizeof(attr), /* to capture ABI version */
- };
- char *evname = strdup(OFFCPU_EVENT);
-
- if (evname == NULL)
- return -ENOMEM;
- evsel = evsel__new(&attr);
- if (!evsel) {
- free(evname);
- return -ENOMEM;
+ scnprintf(off_cpu_event, sizeof(off_cpu_event), "bpf-output/no-inherit=1,name=%s/", OFFCPU_EVENT);
+ if (parse_event(evlist, off_cpu_event)) {
+ pr_err("Failed to open off-cpu event\n");
+ return -1;
}
- evsel->core.attr.freq = 1;
- evsel->core.attr.sample_period = 1;
- /* off-cpu analysis depends on stack trace */
- evsel->core.attr.sample_type = PERF_SAMPLE_CALLCHAIN;
-
- evlist__add(evlist, evsel);
-
- free(evsel->name);
- evsel->name = evname;
+ evlist__for_each_entry(evlist, evsel) {
+ if (evsel__is_offcpu_event(evsel)) {
+ evsel->core.system_wide = true;
+ break;
+ }
+ }
return 0;
}
--
2.43.0
^ permalink raw reply related [flat|nested] 18+ messages in thread* Re: [PATCH v8 03/10] perf record --off-cpu: Parse off-cpu event
2024-11-13 0:28 ` [PATCH v8 03/10] perf record --off-cpu: Parse off-cpu event Howard Chu
@ 2024-11-18 21:17 ` Namhyung Kim
2024-11-18 23:05 ` Howard Chu
0 siblings, 1 reply; 18+ messages in thread
From: Namhyung Kim @ 2024-11-18 21:17 UTC (permalink / raw)
To: Howard Chu
Cc: acme, peterz, irogers, mingo, jolsa, adrian.hunter, kan.liang,
linux-perf-users, linux-kernel, Alexander Shishkin, James Clark,
Mark Rutland, Arnaldo Carvalho de Melo
On Tue, Nov 12, 2024 at 04:28:11PM -0800, Howard Chu wrote:
> Parse the off-cpu event using parse_event(), as bpf-output.
>
> no-inherit should be set to 1, here's the reason:
>
> We update the BPF perf_event map for direct off-cpu sample dumping (in
> following patches), it executes as follows:
>
> bpf_map_update_value()
> bpf_fd_array_map_update_elem()
> perf_event_fd_array_get_ptr()
> perf_event_read_local()
>
> In perf_event_read_local(), there is:
>
> int perf_event_read_local(struct perf_event *event, u64 *value,
> u64 *enabled, u64 *running)
> {
> ...
> /*
> * It must not be an event with inherit set, we cannot read
> * all child counters from atomic context.
> */
> if (event->attr.inherit) {
> ret = -EOPNOTSUPP;
> goto out;
> }
>
> Which means no-inherit has to be true for updating the BPF perf_event
> map.
>
> Moreover, for bpf-output events, we primarily want a system-wide event
> instead of a per-task event.
>
> The reason is that in BPF's bpf_perf_event_output(), BPF uses the CPU
> index to retrieve the perf_event file descriptor it outputs to.
>
> Making a bpf-output event system-wide naturally satisfies this
> requirement by mapping CPU appropriately.
I'm afraid the inherit attribute would be updated later:
__cmd_record()
evlist__config()
evsel__config()
You can add a logic to check the config term when setting the inherit
value.
Thanks,
Namhyung
>
> Suggested-by: Namhyung Kim <namhyung@kernel.org>
> Reviewed-by: Ian Rogers <irogers@google.com>
> Signed-off-by: Howard Chu <howardchu95@gmail.com>
> Cc: Adrian Hunter <adrian.hunter@intel.com>
> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: James Clark <james.clark@linaro.org>
> Cc: Jiri Olsa <jolsa@kernel.org>
> Cc: Kan Liang <kan.liang@linux.intel.com>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Link: https://lore.kernel.org/r/20241108204137.2444151-4-howardchu95@gmail.com
> Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
> ---
> tools/perf/util/bpf_off_cpu.c | 33 +++++++++++----------------------
> 1 file changed, 11 insertions(+), 22 deletions(-)
>
> diff --git a/tools/perf/util/bpf_off_cpu.c b/tools/perf/util/bpf_off_cpu.c
> index a590a8ac1f9d..558c5e5c2dc3 100644
> --- a/tools/perf/util/bpf_off_cpu.c
> +++ b/tools/perf/util/bpf_off_cpu.c
> @@ -38,32 +38,21 @@ union off_cpu_data {
>
> static int off_cpu_config(struct evlist *evlist)
> {
> + char off_cpu_event[64];
> struct evsel *evsel;
> - struct perf_event_attr attr = {
> - .type = PERF_TYPE_SOFTWARE,
> - .config = PERF_COUNT_SW_BPF_OUTPUT,
> - .size = sizeof(attr), /* to capture ABI version */
> - };
> - char *evname = strdup(OFFCPU_EVENT);
> -
> - if (evname == NULL)
> - return -ENOMEM;
>
> - evsel = evsel__new(&attr);
> - if (!evsel) {
> - free(evname);
> - return -ENOMEM;
> + scnprintf(off_cpu_event, sizeof(off_cpu_event), "bpf-output/no-inherit=1,name=%s/", OFFCPU_EVENT);
> + if (parse_event(evlist, off_cpu_event)) {
> + pr_err("Failed to open off-cpu event\n");
> + return -1;
> }
>
> - evsel->core.attr.freq = 1;
> - evsel->core.attr.sample_period = 1;
> - /* off-cpu analysis depends on stack trace */
> - evsel->core.attr.sample_type = PERF_SAMPLE_CALLCHAIN;
> -
> - evlist__add(evlist, evsel);
> -
> - free(evsel->name);
> - evsel->name = evname;
> + evlist__for_each_entry(evlist, evsel) {
> + if (evsel__is_offcpu_event(evsel)) {
> + evsel->core.system_wide = true;
> + break;
> + }
> + }
>
> return 0;
> }
> --
> 2.43.0
>
^ permalink raw reply [flat|nested] 18+ messages in thread* Re: [PATCH v8 03/10] perf record --off-cpu: Parse off-cpu event
2024-11-18 21:17 ` Namhyung Kim
@ 2024-11-18 23:05 ` Howard Chu
0 siblings, 0 replies; 18+ messages in thread
From: Howard Chu @ 2024-11-18 23:05 UTC (permalink / raw)
To: Namhyung Kim
Cc: acme, peterz, irogers, mingo, jolsa, adrian.hunter, kan.liang,
linux-perf-users, linux-kernel, Alexander Shishkin, James Clark,
Mark Rutland, Arnaldo Carvalho de Melo
Hello,
On Mon, Nov 18, 2024 at 1:17 PM Namhyung Kim <namhyung@kernel.org> wrote:
>
> On Tue, Nov 12, 2024 at 04:28:11PM -0800, Howard Chu wrote:
> > Parse the off-cpu event using parse_event(), as bpf-output.
> >
> > no-inherit should be set to 1, here's the reason:
> >
> > We update the BPF perf_event map for direct off-cpu sample dumping (in
> > following patches), it executes as follows:
> >
> > bpf_map_update_value()
> > bpf_fd_array_map_update_elem()
> > perf_event_fd_array_get_ptr()
> > perf_event_read_local()
> >
> > In perf_event_read_local(), there is:
> >
> > int perf_event_read_local(struct perf_event *event, u64 *value,
> > u64 *enabled, u64 *running)
> > {
> > ...
> > /*
> > * It must not be an event with inherit set, we cannot read
> > * all child counters from atomic context.
> > */
> > if (event->attr.inherit) {
> > ret = -EOPNOTSUPP;
> > goto out;
> > }
> >
> > Which means no-inherit has to be true for updating the BPF perf_event
> > map.
> >
> > Moreover, for bpf-output events, we primarily want a system-wide event
> > instead of a per-task event.
> >
> > The reason is that in BPF's bpf_perf_event_output(), BPF uses the CPU
> > index to retrieve the perf_event file descriptor it outputs to.
> >
> > Making a bpf-output event system-wide naturally satisfies this
> > requirement by mapping CPU appropriately.
>
> I'm afraid the inherit attribute would be updated later:
>
> __cmd_record()
> evlist__config()
> evsel__config()
>
> You can add a logic to check the config term when setting the inherit
> value.
Sure.
Thanks,
Howard
>
> Thanks,
> Namhyung
>
> >
> > Suggested-by: Namhyung Kim <namhyung@kernel.org>
> > Reviewed-by: Ian Rogers <irogers@google.com>
> > Signed-off-by: Howard Chu <howardchu95@gmail.com>
> > Cc: Adrian Hunter <adrian.hunter@intel.com>
> > Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
> > Cc: Ingo Molnar <mingo@redhat.com>
> > Cc: James Clark <james.clark@linaro.org>
> > Cc: Jiri Olsa <jolsa@kernel.org>
> > Cc: Kan Liang <kan.liang@linux.intel.com>
> > Cc: Mark Rutland <mark.rutland@arm.com>
> > Cc: Peter Zijlstra <peterz@infradead.org>
> > Link: https://lore.kernel.org/r/20241108204137.2444151-4-howardchu95@gmail.com
> > Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
> > ---
> > tools/perf/util/bpf_off_cpu.c | 33 +++++++++++----------------------
> > 1 file changed, 11 insertions(+), 22 deletions(-)
> >
> > diff --git a/tools/perf/util/bpf_off_cpu.c b/tools/perf/util/bpf_off_cpu.c
> > index a590a8ac1f9d..558c5e5c2dc3 100644
> > --- a/tools/perf/util/bpf_off_cpu.c
> > +++ b/tools/perf/util/bpf_off_cpu.c
> > @@ -38,32 +38,21 @@ union off_cpu_data {
> >
> > static int off_cpu_config(struct evlist *evlist)
> > {
> > + char off_cpu_event[64];
> > struct evsel *evsel;
> > - struct perf_event_attr attr = {
> > - .type = PERF_TYPE_SOFTWARE,
> > - .config = PERF_COUNT_SW_BPF_OUTPUT,
> > - .size = sizeof(attr), /* to capture ABI version */
> > - };
> > - char *evname = strdup(OFFCPU_EVENT);
> > -
> > - if (evname == NULL)
> > - return -ENOMEM;
> >
> > - evsel = evsel__new(&attr);
> > - if (!evsel) {
> > - free(evname);
> > - return -ENOMEM;
> > + scnprintf(off_cpu_event, sizeof(off_cpu_event), "bpf-output/no-inherit=1,name=%s/", OFFCPU_EVENT);
> > + if (parse_event(evlist, off_cpu_event)) {
> > + pr_err("Failed to open off-cpu event\n");
> > + return -1;
> > }
> >
> > - evsel->core.attr.freq = 1;
> > - evsel->core.attr.sample_period = 1;
> > - /* off-cpu analysis depends on stack trace */
> > - evsel->core.attr.sample_type = PERF_SAMPLE_CALLCHAIN;
> > -
> > - evlist__add(evlist, evsel);
> > -
> > - free(evsel->name);
> > - evsel->name = evname;
> > + evlist__for_each_entry(evlist, evsel) {
> > + if (evsel__is_offcpu_event(evsel)) {
> > + evsel->core.system_wide = true;
> > + break;
> > + }
> > + }
> >
> > return 0;
> > }
> > --
> > 2.43.0
> >
^ permalink raw reply [flat|nested] 18+ messages in thread
* [PATCH v8 04/10] perf record --off-cpu: Preparation of off-cpu BPF program
2024-11-13 0:28 [PATCH v8 00/10] perf record --off-cpu: Dump off-cpu samples directly Howard Chu
` (2 preceding siblings ...)
2024-11-13 0:28 ` [PATCH v8 03/10] perf record --off-cpu: Parse off-cpu event Howard Chu
@ 2024-11-13 0:28 ` Howard Chu
2024-11-13 17:03 ` Ian Rogers
2024-11-13 0:28 ` [PATCH v8 05/10] perf record --off-cpu: Dump off-cpu samples in BPF Howard Chu
` (6 subsequent siblings)
10 siblings, 1 reply; 18+ messages in thread
From: Howard Chu @ 2024-11-13 0:28 UTC (permalink / raw)
To: acme, peterz
Cc: namhyung, irogers, mingo, jolsa, adrian.hunter, kan.liang,
linux-perf-users, linux-kernel, Howard Chu, Alexander Shishkin,
James Clark, Mark Rutland, Arnaldo Carvalho de Melo
Set the perf_event map in BPF for dumping off-cpu samples.
Set the offcpu_thresh to specify the threshold.
Reviewed-by: Ian Rogers <irogers@google.com>
Signed-off-by: Howard Chu <howardchu95@gmail.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20241108204137.2444151-5-howardchu95@gmail.com
[ Added some missing iteration variables to off_cpu_config() and fixed up
a manually edited patch hunk line boundary line ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/util/bpf_off_cpu.c | 25 +++++++++++++++++++++++++
tools/perf/util/bpf_skel/off_cpu.bpf.c | 11 +++++++++++
2 files changed, 36 insertions(+)
diff --git a/tools/perf/util/bpf_off_cpu.c b/tools/perf/util/bpf_off_cpu.c
index 558c5e5c2dc3..61729a65b529 100644
--- a/tools/perf/util/bpf_off_cpu.c
+++ b/tools/perf/util/bpf_off_cpu.c
@@ -13,6 +13,7 @@
#include "util/cgroup.h"
#include "util/strlist.h"
#include <bpf/bpf.h>
+#include <internal/xyarray.h>
#include "bpf_skel/off_cpu.skel.h"
@@ -60,6 +61,9 @@ static int off_cpu_config(struct evlist *evlist)
static void off_cpu_start(void *arg)
{
struct evlist *evlist = arg;
+ struct evsel *evsel;
+ struct perf_cpu pcpu;
+ int i;
/* update task filter for the given workload */
if (skel->rodata->has_task && skel->rodata->uses_tgid &&
@@ -73,6 +77,25 @@ static void off_cpu_start(void *arg)
bpf_map_update_elem(fd, &pid, &val, BPF_ANY);
}
+ /* update BPF perf_event map */
+ evsel = evlist__find_evsel_by_str(evlist, OFFCPU_EVENT);
+ if (evsel == NULL) {
+ pr_err("%s evsel not found\n", OFFCPU_EVENT);
+ return;
+ }
+
+ perf_cpu_map__for_each_cpu(pcpu, i, evsel->core.cpus) {
+ int err;
+
+ err = bpf_map__update_elem(skel->maps.offcpu_output, &pcpu.cpu, sizeof(__u32),
+ xyarray__entry(evsel->core.fd, i, 0),
+ sizeof(__u32), BPF_ANY);
+ if (err) {
+ pr_err("Failed to update perf event map for direct off-cpu dumping\n");
+ return;
+ }
+ }
+
skel->bss->enabled = 1;
}
@@ -261,6 +284,8 @@ int off_cpu_prepare(struct evlist *evlist, struct target *target,
}
}
+ skel->bss->offcpu_thresh_ns = opts->off_cpu_thresh_us * 1000;
+
err = off_cpu_bpf__attach(skel);
if (err) {
pr_err("Failed to attach off-cpu BPF skeleton\n");
diff --git a/tools/perf/util/bpf_skel/off_cpu.bpf.c b/tools/perf/util/bpf_skel/off_cpu.bpf.c
index c152116df72f..c87132e01eb3 100644
--- a/tools/perf/util/bpf_skel/off_cpu.bpf.c
+++ b/tools/perf/util/bpf_skel/off_cpu.bpf.c
@@ -18,6 +18,8 @@
#define MAX_STACKS 32
#define MAX_ENTRIES 102400
+#define MAX_CPUS 4096
+
struct tstamp_data {
__u32 stack_id;
__u32 state;
@@ -39,6 +41,13 @@ struct {
__uint(max_entries, MAX_ENTRIES);
} stacks SEC(".maps");
+struct {
+ __uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
+ __uint(key_size, sizeof(__u32));
+ __uint(value_size, sizeof(__u32));
+ __uint(max_entries, MAX_CPUS);
+} offcpu_output SEC(".maps");
+
struct {
__uint(type, BPF_MAP_TYPE_TASK_STORAGE);
__uint(map_flags, BPF_F_NO_PREALLOC);
@@ -97,6 +106,8 @@ const volatile bool uses_cgroup_v1 = false;
int perf_subsys_id = -1;
+__u64 offcpu_thresh_ns;
+
/*
* Old kernel used to call it task_struct->state and now it's '__state'.
* Use BPF CO-RE "ignored suffix rule" to deal with it like below:
--
2.43.0
^ permalink raw reply related [flat|nested] 18+ messages in thread* Re: [PATCH v8 04/10] perf record --off-cpu: Preparation of off-cpu BPF program
2024-11-13 0:28 ` [PATCH v8 04/10] perf record --off-cpu: Preparation of off-cpu BPF program Howard Chu
@ 2024-11-13 17:03 ` Ian Rogers
0 siblings, 0 replies; 18+ messages in thread
From: Ian Rogers @ 2024-11-13 17:03 UTC (permalink / raw)
To: Howard Chu
Cc: acme, peterz, namhyung, mingo, jolsa, adrian.hunter, kan.liang,
linux-perf-users, linux-kernel, Alexander Shishkin, James Clark,
Mark Rutland, Arnaldo Carvalho de Melo
On Tue, Nov 12, 2024 at 4:28 PM Howard Chu <howardchu95@gmail.com> wrote:
>
> Set the perf_event map in BPF for dumping off-cpu samples.
>
> Set the offcpu_thresh to specify the threshold.
>
> Reviewed-by: Ian Rogers <irogers@google.com>
> Signed-off-by: Howard Chu <howardchu95@gmail.com>
> Cc: Adrian Hunter <adrian.hunter@intel.com>
> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: James Clark <james.clark@linaro.org>
> Cc: Jiri Olsa <jolsa@kernel.org>
> Cc: Kan Liang <kan.liang@linux.intel.com>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: Namhyung Kim <namhyung@kernel.org>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Link: https://lore.kernel.org/r/20241108204137.2444151-5-howardchu95@gmail.com
> [ Added some missing iteration variables to off_cpu_config() and fixed up
> a manually edited patch hunk line boundary line ]
> Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
> ---
> tools/perf/util/bpf_off_cpu.c | 25 +++++++++++++++++++++++++
> tools/perf/util/bpf_skel/off_cpu.bpf.c | 11 +++++++++++
> 2 files changed, 36 insertions(+)
>
> diff --git a/tools/perf/util/bpf_off_cpu.c b/tools/perf/util/bpf_off_cpu.c
> index 558c5e5c2dc3..61729a65b529 100644
> --- a/tools/perf/util/bpf_off_cpu.c
> +++ b/tools/perf/util/bpf_off_cpu.c
> @@ -13,6 +13,7 @@
> #include "util/cgroup.h"
> #include "util/strlist.h"
> #include <bpf/bpf.h>
> +#include <internal/xyarray.h>
>
> #include "bpf_skel/off_cpu.skel.h"
>
> @@ -60,6 +61,9 @@ static int off_cpu_config(struct evlist *evlist)
> static void off_cpu_start(void *arg)
> {
> struct evlist *evlist = arg;
> + struct evsel *evsel;
> + struct perf_cpu pcpu;
> + int i;
>
> /* update task filter for the given workload */
> if (skel->rodata->has_task && skel->rodata->uses_tgid &&
> @@ -73,6 +77,25 @@ static void off_cpu_start(void *arg)
> bpf_map_update_elem(fd, &pid, &val, BPF_ANY);
> }
>
> + /* update BPF perf_event map */
> + evsel = evlist__find_evsel_by_str(evlist, OFFCPU_EVENT);
> + if (evsel == NULL) {
> + pr_err("%s evsel not found\n", OFFCPU_EVENT);
> + return;
> + }
> +
> + perf_cpu_map__for_each_cpu(pcpu, i, evsel->core.cpus) {
> + int err;
> +
> + err = bpf_map__update_elem(skel->maps.offcpu_output, &pcpu.cpu, sizeof(__u32),
> + xyarray__entry(evsel->core.fd, i, 0),
> + sizeof(__u32), BPF_ANY);
> + if (err) {
> + pr_err("Failed to update perf event map for direct off-cpu dumping\n");
> + return;
> + }
> + }
> +
> skel->bss->enabled = 1;
> }
>
> @@ -261,6 +284,8 @@ int off_cpu_prepare(struct evlist *evlist, struct target *target,
> }
> }
>
> + skel->bss->offcpu_thresh_ns = opts->off_cpu_thresh_us * 1000;
Thanks for the suffixes, readability++.
Ian
> +
> err = off_cpu_bpf__attach(skel);
> if (err) {
> pr_err("Failed to attach off-cpu BPF skeleton\n");
> diff --git a/tools/perf/util/bpf_skel/off_cpu.bpf.c b/tools/perf/util/bpf_skel/off_cpu.bpf.c
> index c152116df72f..c87132e01eb3 100644
> --- a/tools/perf/util/bpf_skel/off_cpu.bpf.c
> +++ b/tools/perf/util/bpf_skel/off_cpu.bpf.c
> @@ -18,6 +18,8 @@
> #define MAX_STACKS 32
> #define MAX_ENTRIES 102400
>
> +#define MAX_CPUS 4096
> +
> struct tstamp_data {
> __u32 stack_id;
> __u32 state;
> @@ -39,6 +41,13 @@ struct {
> __uint(max_entries, MAX_ENTRIES);
> } stacks SEC(".maps");
>
> +struct {
> + __uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
> + __uint(key_size, sizeof(__u32));
> + __uint(value_size, sizeof(__u32));
> + __uint(max_entries, MAX_CPUS);
> +} offcpu_output SEC(".maps");
> +
> struct {
> __uint(type, BPF_MAP_TYPE_TASK_STORAGE);
> __uint(map_flags, BPF_F_NO_PREALLOC);
> @@ -97,6 +106,8 @@ const volatile bool uses_cgroup_v1 = false;
>
> int perf_subsys_id = -1;
>
> +__u64 offcpu_thresh_ns;
> +
> /*
> * Old kernel used to call it task_struct->state and now it's '__state'.
> * Use BPF CO-RE "ignored suffix rule" to deal with it like below:
> --
> 2.43.0
>
^ permalink raw reply [flat|nested] 18+ messages in thread
* [PATCH v8 05/10] perf record --off-cpu: Dump off-cpu samples in BPF
2024-11-13 0:28 [PATCH v8 00/10] perf record --off-cpu: Dump off-cpu samples directly Howard Chu
` (3 preceding siblings ...)
2024-11-13 0:28 ` [PATCH v8 04/10] perf record --off-cpu: Preparation of off-cpu BPF program Howard Chu
@ 2024-11-13 0:28 ` Howard Chu
2024-11-13 0:28 ` [PATCH v8 06/10] perf evsel: Assemble offcpu samples Howard Chu
` (5 subsequent siblings)
10 siblings, 0 replies; 18+ messages in thread
From: Howard Chu @ 2024-11-13 0:28 UTC (permalink / raw)
To: acme, peterz
Cc: namhyung, irogers, mingo, jolsa, adrian.hunter, kan.liang,
linux-perf-users, linux-kernel, Howard Chu, Alexander Shishkin,
James Clark, Mark Rutland, Arnaldo Carvalho de Melo
Collect tid, period, callchain, and cgroup id and dump them when off-cpu
time threshold is reached.
We don't collect the off-cpu time twice (the delta), it's either in
direct samples, or accumulated samples that are dumped at the end of
perf.data.
Suggested-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Howard Chu <howardchu95@gmail.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20241108204137.2444151-6-howardchu95@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/util/bpf_skel/off_cpu.bpf.c | 86 ++++++++++++++++++++++++--
1 file changed, 81 insertions(+), 5 deletions(-)
diff --git a/tools/perf/util/bpf_skel/off_cpu.bpf.c b/tools/perf/util/bpf_skel/off_cpu.bpf.c
index c87132e01eb3..aae63d999abb 100644
--- a/tools/perf/util/bpf_skel/off_cpu.bpf.c
+++ b/tools/perf/util/bpf_skel/off_cpu.bpf.c
@@ -19,11 +19,17 @@
#define MAX_ENTRIES 102400
#define MAX_CPUS 4096
+#define MAX_OFFCPU_LEN 37
+
+struct stack {
+ u64 array[MAX_STACKS];
+};
struct tstamp_data {
__u32 stack_id;
__u32 state;
__u64 timestamp;
+ struct stack stack;
};
struct offcpu_key {
@@ -41,6 +47,10 @@ struct {
__uint(max_entries, MAX_ENTRIES);
} stacks SEC(".maps");
+struct offcpu_data {
+ u64 array[MAX_OFFCPU_LEN];
+};
+
struct {
__uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
__uint(key_size, sizeof(__u32));
@@ -48,6 +58,13 @@ struct {
__uint(max_entries, MAX_CPUS);
} offcpu_output SEC(".maps");
+struct {
+ __uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
+ __uint(key_size, sizeof(__u32));
+ __uint(value_size, sizeof(struct offcpu_data));
+ __uint(max_entries, 1);
+} offcpu_payload SEC(".maps");
+
struct {
__uint(type, BPF_MAP_TYPE_TASK_STORAGE);
__uint(map_flags, BPF_F_NO_PREALLOC);
@@ -194,6 +211,47 @@ static inline int can_record(struct task_struct *t, int state)
return 1;
}
+static inline int copy_stack(struct stack *from, struct offcpu_data *to, int n)
+{
+ int len = 0;
+
+ for (int i = 0; i < MAX_STACKS && from->array[i]; ++i, ++len)
+ to->array[n + 2 + i] = from->array[i];
+
+ return len;
+}
+
+/**
+ * off_cpu_dump - dump off-cpu samples to ring buffer
+ * @data: payload for dumping off-cpu samples
+ * @key: off-cpu data
+ * @stack: stack trace of the task before being scheduled out
+ *
+ * If the threshold of off-cpu time is reached, acquire tid, period, callchain, and cgroup id
+ * information of the task, and dump it as a raw sample to perf ring buffer
+ */
+static int off_cpu_dump(void *ctx, struct offcpu_data *data, struct offcpu_key *key,
+ struct stack *stack, __u64 delta)
+{
+ int n = 0, len = 0;
+
+ data->array[n++] = (u64)key->tgid << 32 | key->pid;
+ data->array[n++] = delta;
+
+ /* data->array[n] is callchain->nr (updated later) */
+ data->array[n + 1] = PERF_CONTEXT_USER;
+ data->array[n + 2] = 0;
+ len = copy_stack(stack, data, n);
+
+ /* update length of callchain */
+ data->array[n] = len + 1;
+ n += len + 2;
+
+ data->array[n++] = key->cgroup_id;
+
+ return bpf_perf_event_output(ctx, &offcpu_output, BPF_F_CURRENT_CPU, data, n * sizeof(u64));
+}
+
static int off_cpu_stat(u64 *ctx, struct task_struct *prev,
struct task_struct *next, int state)
{
@@ -218,6 +276,16 @@ static int off_cpu_stat(u64 *ctx, struct task_struct *prev,
pelem->state = state;
pelem->stack_id = stack_id;
+ /*
+ * If stacks are successfully collected by bpf_get_stackid(), collect them once more
+ * in task_storage for direct off-cpu sample dumping
+ */
+ if (stack_id > 0 && bpf_get_stack(ctx, &pelem->stack, MAX_STACKS * sizeof(u64), BPF_F_USER_STACK)) {
+ /*
+ * This empty if block is used to avoid 'result unused warning' from bpf_get_stack().
+ * If the collection fails, continue with the logic for the next task.
+ */
+ }
next:
pelem = bpf_task_storage_get(&tstamp, next, NULL, 0);
@@ -232,11 +300,19 @@ static int off_cpu_stat(u64 *ctx, struct task_struct *prev,
__u64 delta = ts - pelem->timestamp;
__u64 *total;
- total = bpf_map_lookup_elem(&off_cpu, &key);
- if (total)
- *total += delta;
- else
- bpf_map_update_elem(&off_cpu, &key, &delta, BPF_ANY);
+ if (delta >= offcpu_thresh_ns) {
+ int zero = 0;
+ struct offcpu_data *data = bpf_map_lookup_elem(&offcpu_payload, &zero);
+
+ if (data)
+ off_cpu_dump(ctx, data, &key, &pelem->stack, delta);
+ } else {
+ total = bpf_map_lookup_elem(&off_cpu, &key);
+ if (total)
+ *total += delta;
+ else
+ bpf_map_update_elem(&off_cpu, &key, &delta, BPF_ANY);
+ }
/* prevent to reuse the timestamp later */
pelem->timestamp = 0;
--
2.43.0
^ permalink raw reply related [flat|nested] 18+ messages in thread* [PATCH v8 06/10] perf evsel: Assemble offcpu samples
2024-11-13 0:28 [PATCH v8 00/10] perf record --off-cpu: Dump off-cpu samples directly Howard Chu
` (4 preceding siblings ...)
2024-11-13 0:28 ` [PATCH v8 05/10] perf record --off-cpu: Dump off-cpu samples in BPF Howard Chu
@ 2024-11-13 0:28 ` Howard Chu
2024-11-18 21:46 ` Namhyung Kim
2024-11-13 0:28 ` [PATCH v8 07/10] perf record --off-cpu: Disable perf_event's callchain collection Howard Chu
` (4 subsequent siblings)
10 siblings, 1 reply; 18+ messages in thread
From: Howard Chu @ 2024-11-13 0:28 UTC (permalink / raw)
To: acme, peterz
Cc: namhyung, irogers, mingo, jolsa, adrian.hunter, kan.liang,
linux-perf-users, linux-kernel, Howard Chu, Alexander Shishkin,
James Clark, Mark Rutland, Arnaldo Carvalho de Melo
Use the data in bpf-output samples, to assemble offcpu samples.
Suggested-by: Namhyung Kim <namhyung@kernel.org>
Reviewed-by: Ian Rogers <irogers@google.com>
Signed-off-by: Howard Chu <howardchu95@gmail.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20241108204137.2444151-7-howardchu95@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/util/evsel.c | 32 ++++++++++++++++++++++++++++++++
1 file changed, 32 insertions(+)
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 8d0308f62484..654fb5196ecf 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -2792,6 +2792,35 @@ static inline bool evsel__has_branch_counters(const struct evsel *evsel)
return false;
}
+static int __set_offcpu_sample(struct perf_sample *data)
+{
+ u64 *array = data->raw_data;
+ u32 max_size = data->raw_size, *p32;
+ const void *endp = (void *)array + max_size;
+
+ if (array == NULL)
+ return -EFAULT;
+
+ OVERFLOW_CHECK_u64(array);
+ p32 = (void *)array++;
+ data->pid = p32[0];
+ data->tid = p32[1];
+
+ OVERFLOW_CHECK_u64(array);
+ data->period = *array++;
+
+ OVERFLOW_CHECK_u64(array);
+ data->callchain = (struct ip_callchain *)array++;
+ OVERFLOW_CHECK(array, data->callchain->nr * sizeof(u64), max_size);
+ data->ip = data->callchain->ips[1];
+ array += data->callchain->nr;
+
+ OVERFLOW_CHECK_u64(array);
+ data->cgroup = *array;
+
+ return 0;
+}
+
int evsel__parse_sample(struct evsel *evsel, union perf_event *event,
struct perf_sample *data)
{
@@ -3143,6 +3172,9 @@ int evsel__parse_sample(struct evsel *evsel, union perf_event *event,
array = (void *)array + sz;
}
+ if (evsel__is_offcpu_event(evsel))
+ return __set_offcpu_sample(data);
+
return 0;
}
--
2.43.0
^ permalink raw reply related [flat|nested] 18+ messages in thread* Re: [PATCH v8 06/10] perf evsel: Assemble offcpu samples
2024-11-13 0:28 ` [PATCH v8 06/10] perf evsel: Assemble offcpu samples Howard Chu
@ 2024-11-18 21:46 ` Namhyung Kim
0 siblings, 0 replies; 18+ messages in thread
From: Namhyung Kim @ 2024-11-18 21:46 UTC (permalink / raw)
To: Howard Chu
Cc: acme, peterz, irogers, mingo, jolsa, adrian.hunter, kan.liang,
linux-perf-users, linux-kernel, Alexander Shishkin, James Clark,
Mark Rutland, Arnaldo Carvalho de Melo
On Tue, Nov 12, 2024 at 04:28:14PM -0800, Howard Chu wrote:
> Use the data in bpf-output samples, to assemble offcpu samples.
Now it requires PERF_SAMPLE_RAW for the off-cpu events. But it's not
compatible with the earlier format. Can you please make sure if it can
read old off-cpu data recorded before your change? Maybe you need to
check or add new info (like in a header.misc field) to distinguish them.
Thanks,
Namhyung
>
> Suggested-by: Namhyung Kim <namhyung@kernel.org>
> Reviewed-by: Ian Rogers <irogers@google.com>
> Signed-off-by: Howard Chu <howardchu95@gmail.com>
> Cc: Adrian Hunter <adrian.hunter@intel.com>
> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: James Clark <james.clark@linaro.org>
> Cc: Jiri Olsa <jolsa@kernel.org>
> Cc: Kan Liang <kan.liang@linux.intel.com>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Link: https://lore.kernel.org/r/20241108204137.2444151-7-howardchu95@gmail.com
> Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
> ---
> tools/perf/util/evsel.c | 32 ++++++++++++++++++++++++++++++++
> 1 file changed, 32 insertions(+)
>
> diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
> index 8d0308f62484..654fb5196ecf 100644
> --- a/tools/perf/util/evsel.c
> +++ b/tools/perf/util/evsel.c
> @@ -2792,6 +2792,35 @@ static inline bool evsel__has_branch_counters(const struct evsel *evsel)
> return false;
> }
>
> +static int __set_offcpu_sample(struct perf_sample *data)
> +{
> + u64 *array = data->raw_data;
> + u32 max_size = data->raw_size, *p32;
> + const void *endp = (void *)array + max_size;
> +
> + if (array == NULL)
> + return -EFAULT;
> +
> + OVERFLOW_CHECK_u64(array);
> + p32 = (void *)array++;
> + data->pid = p32[0];
> + data->tid = p32[1];
> +
> + OVERFLOW_CHECK_u64(array);
> + data->period = *array++;
> +
> + OVERFLOW_CHECK_u64(array);
> + data->callchain = (struct ip_callchain *)array++;
> + OVERFLOW_CHECK(array, data->callchain->nr * sizeof(u64), max_size);
> + data->ip = data->callchain->ips[1];
> + array += data->callchain->nr;
> +
> + OVERFLOW_CHECK_u64(array);
> + data->cgroup = *array;
> +
> + return 0;
> +}
> +
> int evsel__parse_sample(struct evsel *evsel, union perf_event *event,
> struct perf_sample *data)
> {
> @@ -3143,6 +3172,9 @@ int evsel__parse_sample(struct evsel *evsel, union perf_event *event,
> array = (void *)array + sz;
> }
>
> + if (evsel__is_offcpu_event(evsel))
> + return __set_offcpu_sample(data);
> +
> return 0;
> }
>
> --
> 2.43.0
>
^ permalink raw reply [flat|nested] 18+ messages in thread
* [PATCH v8 07/10] perf record --off-cpu: Disable perf_event's callchain collection
2024-11-13 0:28 [PATCH v8 00/10] perf record --off-cpu: Dump off-cpu samples directly Howard Chu
` (5 preceding siblings ...)
2024-11-13 0:28 ` [PATCH v8 06/10] perf evsel: Assemble offcpu samples Howard Chu
@ 2024-11-13 0:28 ` Howard Chu
2024-11-13 0:28 ` [PATCH v8 08/10] perf script: Display off-cpu samples correctly Howard Chu
` (3 subsequent siblings)
10 siblings, 0 replies; 18+ messages in thread
From: Howard Chu @ 2024-11-13 0:28 UTC (permalink / raw)
To: acme, peterz
Cc: namhyung, irogers, mingo, jolsa, adrian.hunter, kan.liang,
linux-perf-users, linux-kernel, Howard Chu, Alexander Shishkin,
James Clark, Mark Rutland, Arnaldo Carvalho de Melo
There is a check in evsel.c that does this:
if (evsel__is_offcpu_event(evsel))
evsel->core.attr.sample_type &= OFFCPU_SAMPLE_TYPES;
This along with:
#define OFFCPU_SAMPLE_TYPES (PERF_SAMPLE_IDENTIFIER | PERF_SAMPLE_IP | \
PERF_SAMPLE_TID | PERF_SAMPLE_TIME | \
PERF_SAMPLE_ID | PERF_SAMPLE_CPU | \
PERF_SAMPLE_PERIOD | PERF_SAMPLE_CALLCHAIN | \
PERF_SAMPLE_CGROUP)
will tell perf_event to collect callchain.
We don't need the callchain from perf_event when collecting off-cpu
samples, because it's prev's callchain, not next's callchain.
(perf_event) (task_storage) (needed)
prev next
| |
---sched_switch---->
Signed-off-by: Howard Chu <howardchu95@gmail.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20241108204137.2444151-8-howardchu95@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/util/off_cpu.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/tools/perf/util/off_cpu.h b/tools/perf/util/off_cpu.h
index c6edc0f7c40d..f07ab2e36317 100644
--- a/tools/perf/util/off_cpu.h
+++ b/tools/perf/util/off_cpu.h
@@ -13,7 +13,7 @@ struct record_opts;
#define OFFCPU_SAMPLE_TYPES (PERF_SAMPLE_IDENTIFIER | PERF_SAMPLE_IP | \
PERF_SAMPLE_TID | PERF_SAMPLE_TIME | \
PERF_SAMPLE_ID | PERF_SAMPLE_CPU | \
- PERF_SAMPLE_PERIOD | PERF_SAMPLE_CALLCHAIN | \
+ PERF_SAMPLE_PERIOD | PERF_SAMPLE_RAW | \
PERF_SAMPLE_CGROUP)
#define OFFCPU_THRESH 500000ull
--
2.43.0
^ permalink raw reply related [flat|nested] 18+ messages in thread* [PATCH v8 08/10] perf script: Display off-cpu samples correctly
2024-11-13 0:28 [PATCH v8 00/10] perf record --off-cpu: Dump off-cpu samples directly Howard Chu
` (6 preceding siblings ...)
2024-11-13 0:28 ` [PATCH v8 07/10] perf record --off-cpu: Disable perf_event's callchain collection Howard Chu
@ 2024-11-13 0:28 ` Howard Chu
2024-11-13 0:28 ` [PATCH v8 09/10] perf record --off-cpu: Dump the remaining samples in BPF's stack trace map Howard Chu
` (2 subsequent siblings)
10 siblings, 0 replies; 18+ messages in thread
From: Howard Chu @ 2024-11-13 0:28 UTC (permalink / raw)
To: acme, peterz
Cc: namhyung, irogers, mingo, jolsa, adrian.hunter, kan.liang,
linux-perf-users, linux-kernel, Howard Chu, Alexander Shishkin,
James Clark, Mark Rutland, Arnaldo Carvalho de Melo
No PERF_SAMPLE_CALLCHAIN in sample_type, but I need perf script to
display a callchain, have to specify manually.
Also, prefer displaying a callchain:
gvfs-afc-volume 2267 [001] 3829232.955656: 1001115340 offcpu-time:
77f05292603f __pselect+0xbf (/usr/lib/x86_64-linux-gnu/libc.so.6)
77f052a1801c [unknown] (/usr/lib/x86_64-linux-gnu/libusbmuxd-2.0.so.6.0.0)
77f052a18d45 [unknown] (/usr/lib/x86_64-linux-gnu/libusbmuxd-2.0.so.6.0.0)
77f05289ca94 start_thread+0x384 (/usr/lib/x86_64-linux-gnu/libc.so.6)
77f052929c3c clone3+0x2c (/usr/lib/x86_64-linux-gnu/libc.so.6)
to a raw binary BPF output:
BPF output: 0000: dd 08 00 00 db 08 00 00 <DD>...<DB>...
0008: cc ce ab 3b 00 00 00 00 <CC>Ϋ;....
0010: 06 00 00 00 00 00 00 00 ........
0018: 00 fe ff ff ff ff ff ff .<FE><FF><FF><FF><FF><FF><FF>
0020: 3f 60 92 52 f0 77 00 00 ?`.R<F0>w..
0028: 1c 80 a1 52 f0 77 00 00 ..<A1>R<F0>w..
0030: 45 8d a1 52 f0 77 00 00 E.<A1>R<F0>w..
0038: 94 ca 89 52 f0 77 00 00 .<CA>.R<F0>w..
0040: 3c 9c 92 52 f0 77 00 00 <..R<F0>w..
0048: 00 00 00 00 00 00 00 00 ........
0050: 00 00 00 00 ....
Reviewed-by: Ian Rogers <irogers@google.com>
Signed-off-by: Howard Chu <howardchu95@gmail.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20241108204137.2444151-9-howardchu95@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/builtin-script.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c
index 9e47905f75a6..dd0f95c51571 100644
--- a/tools/perf/builtin-script.c
+++ b/tools/perf/builtin-script.c
@@ -662,7 +662,7 @@ static int perf_session__check_output_opt(struct perf_session *session)
evlist__for_each_entry(session->evlist, evsel) {
not_pipe = true;
- if (evsel__has_callchain(evsel)) {
+ if (evsel__has_callchain(evsel) || evsel__is_offcpu_event(evsel)) {
use_callchain = true;
break;
}
@@ -2353,7 +2353,7 @@ static void process_event(struct perf_script *script,
else if (PRINT_FIELD(BRSTACKOFF))
perf_sample__fprintf_brstackoff(sample, thread, attr, fp);
- if (evsel__is_bpf_output(evsel) && PRINT_FIELD(BPF_OUTPUT))
+ if (evsel__is_bpf_output(evsel) && !evsel__is_offcpu_event(evsel) && PRINT_FIELD(BPF_OUTPUT))
perf_sample__fprintf_bpf_output(sample, fp);
perf_sample__fprintf_insn(sample, evsel, attr, thread, machine, fp, al);
--
2.43.0
^ permalink raw reply related [flat|nested] 18+ messages in thread* [PATCH v8 09/10] perf record --off-cpu: Dump the remaining samples in BPF's stack trace map
2024-11-13 0:28 [PATCH v8 00/10] perf record --off-cpu: Dump off-cpu samples directly Howard Chu
` (7 preceding siblings ...)
2024-11-13 0:28 ` [PATCH v8 08/10] perf script: Display off-cpu samples correctly Howard Chu
@ 2024-11-13 0:28 ` Howard Chu
2024-11-13 0:28 ` [PATCH v8 10/10] perf test: Add direct off-cpu test Howard Chu
2024-11-13 17:08 ` [PATCH v8 00/10] perf record --off-cpu: Dump off-cpu samples directly Ian Rogers
10 siblings, 0 replies; 18+ messages in thread
From: Howard Chu @ 2024-11-13 0:28 UTC (permalink / raw)
To: acme, peterz
Cc: namhyung, irogers, mingo, jolsa, adrian.hunter, kan.liang,
linux-perf-users, linux-kernel, Howard Chu, Alexander Shishkin,
James Clark, Mark Rutland, Arnaldo Carvalho de Melo
Dump the remaining samples, as if it is dumping a direct sample.
Put the stack trace, tid, off-cpu time and cgroup id into the raw_data
section, just like a direct off-cpu sample coming from BPF's
bpf_perf_event_output().
This ensures that evsel__parse_sample() correctly parses both direct
samples and accumulated samples.
Suggested-by: Namhyung Kim <namhyung@kernel.org>
Reviewed-by: Ian Rogers <irogers@google.com>
Signed-off-by: Howard Chu <howardchu95@gmail.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20241108204137.2444151-10-howardchu95@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/util/bpf_off_cpu.c | 59 +++++++++++++++++++++--------------
1 file changed, 35 insertions(+), 24 deletions(-)
diff --git a/tools/perf/util/bpf_off_cpu.c b/tools/perf/util/bpf_off_cpu.c
index 61729a65b529..16528f8509b7 100644
--- a/tools/perf/util/bpf_off_cpu.c
+++ b/tools/perf/util/bpf_off_cpu.c
@@ -37,6 +37,8 @@ union off_cpu_data {
u64 array[1024 / sizeof(u64)];
};
+u64 off_cpu_raw[MAX_STACKS + 5];
+
static int off_cpu_config(struct evlist *evlist)
{
char off_cpu_event[64];
@@ -309,6 +311,7 @@ int off_cpu_write(struct perf_session *session)
{
int bytes = 0, size;
int fd, stack;
+ u32 raw_size;
u64 sample_type, val, sid = 0;
struct evsel *evsel;
struct perf_data_file *file = &session->data->file;
@@ -348,46 +351,54 @@ int off_cpu_write(struct perf_session *session)
while (!bpf_map_get_next_key(fd, &prev, &key)) {
int n = 1; /* start from perf_event_header */
- int ip_pos = -1;
bpf_map_lookup_elem(fd, &key, &val);
+ /* zero-fill some of the fields, will be overwritten by raw_data when parsing */
if (sample_type & PERF_SAMPLE_IDENTIFIER)
data.array[n++] = sid;
- if (sample_type & PERF_SAMPLE_IP) {
- ip_pos = n;
+ if (sample_type & PERF_SAMPLE_IP)
data.array[n++] = 0; /* will be updated */
- }
if (sample_type & PERF_SAMPLE_TID)
- data.array[n++] = (u64)key.pid << 32 | key.tgid;
+ data.array[n++] = 0;
if (sample_type & PERF_SAMPLE_TIME)
data.array[n++] = tstamp;
- if (sample_type & PERF_SAMPLE_ID)
- data.array[n++] = sid;
if (sample_type & PERF_SAMPLE_CPU)
data.array[n++] = 0;
if (sample_type & PERF_SAMPLE_PERIOD)
- data.array[n++] = val;
- if (sample_type & PERF_SAMPLE_CALLCHAIN) {
- int len = 0;
-
- /* data.array[n] is callchain->nr (updated later) */
- data.array[n + 1] = PERF_CONTEXT_USER;
- data.array[n + 2] = 0;
-
- bpf_map_lookup_elem(stack, &key.stack_id, &data.array[n + 2]);
- while (data.array[n + 2 + len])
+ data.array[n++] = 0;
+ if (sample_type & PERF_SAMPLE_RAW) {
+ /*
+ * [ size ][ data ]
+ * [ data ]
+ * [ data ]
+ * [ data ]
+ * [ data ][ empty]
+ */
+ int len = 0, i = 0;
+ void *raw_data = (void *)data.array + n * sizeof(u64);
+
+ off_cpu_raw[i++] = (u64)key.pid << 32 | key.tgid;
+ off_cpu_raw[i++] = val;
+
+ /* off_cpu_raw[i] is callchain->nr (updated later) */
+ off_cpu_raw[i + 1] = PERF_CONTEXT_USER;
+ off_cpu_raw[i + 2] = 0;
+
+ bpf_map_lookup_elem(stack, &key.stack_id, &off_cpu_raw[i + 2]);
+ while (off_cpu_raw[i + 2 + len])
len++;
- /* update length of callchain */
- data.array[n] = len + 1;
+ off_cpu_raw[i] = len + 1;
+ i += len + 2;
+
+ off_cpu_raw[i++] = key.cgroup_id;
- /* update sample ip with the first callchain entry */
- if (ip_pos >= 0)
- data.array[ip_pos] = data.array[n + 2];
+ raw_size = i * sizeof(u64) + sizeof(u32); /* 4 bytes for alignment */
+ memcpy(raw_data, &raw_size, sizeof(raw_size));
+ memcpy(raw_data + sizeof(u32), off_cpu_raw, i * sizeof(u64));
- /* calculate sample callchain data array length */
- n += len + 2;
+ n += i + 1;
}
if (sample_type & PERF_SAMPLE_CGROUP)
data.array[n++] = key.cgroup_id;
--
2.43.0
^ permalink raw reply related [flat|nested] 18+ messages in thread* [PATCH v8 10/10] perf test: Add direct off-cpu test
2024-11-13 0:28 [PATCH v8 00/10] perf record --off-cpu: Dump off-cpu samples directly Howard Chu
` (8 preceding siblings ...)
2024-11-13 0:28 ` [PATCH v8 09/10] perf record --off-cpu: Dump the remaining samples in BPF's stack trace map Howard Chu
@ 2024-11-13 0:28 ` Howard Chu
2024-11-13 17:08 ` [PATCH v8 00/10] perf record --off-cpu: Dump off-cpu samples directly Ian Rogers
10 siblings, 0 replies; 18+ messages in thread
From: Howard Chu @ 2024-11-13 0:28 UTC (permalink / raw)
To: acme, peterz
Cc: namhyung, irogers, mingo, jolsa, adrian.hunter, kan.liang,
linux-perf-users, linux-kernel, Howard Chu, Alexander Shishkin,
James Clark, Mark Rutland, Arnaldo Carvalho de Melo
Why is there a --off-cpu-thresh 2000000?
We collect an off-cpu period __ONLY ONCE__, either in direct sample form,
or in accumulated form (in BPF stack trace map).
If I don't add --off-cpu-thresh 200000, the sample in the original test
goes into the ring buffer instead of the BPF stack trace map.
Additionally, when using -e dummy, the ring buffer is not open, causing
us to lose a sample.
Signed-off-by: Howard Chu <howardchu95@gmail.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20241108204137.2444151-11-howardchu95@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/tests/builtin-test.c | 1 +
tools/perf/tests/shell/record_offcpu.sh | 35 ++++++++++++++++++++++++-
tools/perf/tests/tests.h | 1 +
tools/perf/tests/workloads/Build | 1 +
tools/perf/tests/workloads/offcpu.c | 16 +++++++++++
5 files changed, 53 insertions(+), 1 deletion(-)
create mode 100644 tools/perf/tests/workloads/offcpu.c
diff --git a/tools/perf/tests/builtin-test.c b/tools/perf/tests/builtin-test.c
index 8dcf74d3c0a3..43dc04075ecb 100644
--- a/tools/perf/tests/builtin-test.c
+++ b/tools/perf/tests/builtin-test.c
@@ -146,6 +146,7 @@ static struct test_workload *workloads[] = {
&workload__brstack,
&workload__datasym,
&workload__landlock,
+ &workload__offcpu,
};
#define workloads__for_each(workload) \
diff --git a/tools/perf/tests/shell/record_offcpu.sh b/tools/perf/tests/shell/record_offcpu.sh
index 678947fe69ee..8719130fbf70 100755
--- a/tools/perf/tests/shell/record_offcpu.sh
+++ b/tools/perf/tests/shell/record_offcpu.sh
@@ -6,6 +6,10 @@ set -e
err=0
perfdata=$(mktemp /tmp/__perf_test.perf.data.XXXXX)
+TEST_PROGRAM="perf test -w offcpu"
+
+ts=$(printf "%u" $((~0 << 32))) # OFF_CPU_TIMESTAMP
+dummy_timestamp=${ts%???} # remove the last 3 digits to match perf script
cleanup() {
rm -f ${perfdata}
@@ -39,7 +43,11 @@ test_offcpu_priv() {
test_offcpu_basic() {
echo "Basic off-cpu test"
- if ! perf record --off-cpu -e dummy -o ${perfdata} sleep 1 2> /dev/null
+ # We collect an off-cpu period __ONLY ONCE__, either in direct sample form, or in accumulated form
+ # (in BPF stack trace map). Without the --off-cpu-thresh 200000 below, the sample will go into the
+ # ring buffer instead of the BPF stack trace map. Additionally, when using -e dummy, the ring
+ # buffer is not enabled, resulting in a lost sample.
+ if ! perf record --off-cpu --off-cpu-thresh 2000000 -e dummy -o ${perfdata} sleep 1 2> /dev/null
then
echo "Basic off-cpu test [Failed record]"
err=1
@@ -88,6 +96,27 @@ test_offcpu_child() {
echo "Child task off-cpu test [Success]"
}
+test_offcpu_direct() {
+ echo "Direct off-cpu test"
+
+ # dump off-cpu samples for task blocked for more than 1.999999s
+ # -D for initial delay, to enable evlist
+ if ! perf record -e dummy -D 500 --off-cpu --off-cpu-thresh 1999999 -o ${perfdata} ${TEST_PROGRAM} 2> /dev/null
+ then
+ echo "Direct off-cpu test [Failed record]"
+ err=1
+ return
+ fi
+ # Direct sample's timestamp should be lower than the dummy_timestamp of the at-the-end sample.
+ if ! perf script -i ${perfdata} -F time,period | sed "s/[\.:]//g" | \
+ awk "{ if (\$1 < ${dummy_timestamp} && \$2 > 1999999999) exit 0; else exit 1; }"
+ then
+ echo "Direct off-cpu test [Failed missing direct sample]"
+ err=1
+ return
+ fi
+ echo "Direct off-cpu test [Success]"
+}
test_offcpu_priv
@@ -99,5 +128,9 @@ if [ $err = 0 ]; then
test_offcpu_child
fi
+if [ $err = 0 ]; then
+ test_offcpu_direct
+fi
+
cleanup
exit $err
diff --git a/tools/perf/tests/tests.h b/tools/perf/tests/tests.h
index cb58b43aa063..2e655a617b30 100644
--- a/tools/perf/tests/tests.h
+++ b/tools/perf/tests/tests.h
@@ -217,6 +217,7 @@ DECLARE_WORKLOAD(sqrtloop);
DECLARE_WORKLOAD(brstack);
DECLARE_WORKLOAD(datasym);
DECLARE_WORKLOAD(landlock);
+DECLARE_WORKLOAD(offcpu);
extern const char *dso_to_test;
extern const char *test_objdump_path;
diff --git a/tools/perf/tests/workloads/Build b/tools/perf/tests/workloads/Build
index 5af17206f04d..0e78fd01eaf1 100644
--- a/tools/perf/tests/workloads/Build
+++ b/tools/perf/tests/workloads/Build
@@ -7,6 +7,7 @@ perf-test-y += sqrtloop.o
perf-test-y += brstack.o
perf-test-y += datasym.o
perf-test-y += landlock.o
+perf-test-y += offcpu.o
CFLAGS_sqrtloop.o = -g -O0 -fno-inline -U_FORTIFY_SOURCE
CFLAGS_leafloop.o = -g -O0 -fno-inline -fno-omit-frame-pointer -U_FORTIFY_SOURCE
diff --git a/tools/perf/tests/workloads/offcpu.c b/tools/perf/tests/workloads/offcpu.c
new file mode 100644
index 000000000000..57cee201a4c3
--- /dev/null
+++ b/tools/perf/tests/workloads/offcpu.c
@@ -0,0 +1,16 @@
+#include <linux/compiler.h>
+#include <unistd.h>
+#include "../tests.h"
+
+static int offcpu(int argc __maybe_unused, const char **argv __maybe_unused)
+{
+ /* get past the initial delay */
+ sleep(1);
+
+ /* what we want to collect as a direct sample */
+ sleep(2);
+
+ return 0;
+}
+
+DEFINE_WORKLOAD(offcpu);
--
2.43.0
^ permalink raw reply related [flat|nested] 18+ messages in thread* Re: [PATCH v8 00/10] perf record --off-cpu: Dump off-cpu samples directly
2024-11-13 0:28 [PATCH v8 00/10] perf record --off-cpu: Dump off-cpu samples directly Howard Chu
` (9 preceding siblings ...)
2024-11-13 0:28 ` [PATCH v8 10/10] perf test: Add direct off-cpu test Howard Chu
@ 2024-11-13 17:08 ` Ian Rogers
10 siblings, 0 replies; 18+ messages in thread
From: Ian Rogers @ 2024-11-13 17:08 UTC (permalink / raw)
To: Howard Chu
Cc: acme, peterz, namhyung, mingo, jolsa, adrian.hunter, kan.liang,
linux-perf-users, linux-kernel
On Tue, Nov 12, 2024 at 4:28 PM Howard Chu <howardchu95@gmail.com> wrote:
>
> Changes in v8:
> - Make this series bisectable
> - Rename off_cpu_thresh to off_cpu_thresh_us and offcpu_thresh (in BPF)
> to offcpu_thresh_ns for clarity.
> - Add commit messages to 'perf evsel: Expose evsel__is_offcpu_event()
> for future use' commit
> - Correct spelling mistakes in the commit message (s/is should be/should be/)
> - Add kernel-doc comments to off_cpu_dump(), and comments to the empty
> if block
> - Add some comments to off-cpu test
> - Delete an unused variable 'timestamp' in off_cpu_dump()
I spotted a few issues in v7, but v8 looks good to me.
Reviewed-by: Ian Rogers <irogers@google.com>
Thanks,
Ian
> Changes in v7:
> - Make off-cpu event system-wide
> - Use strtoull instead of strtoul
> - Delete unused variable such as sample_id, and sample_type
> - Use i as index to update BPF perf_event map
> - MAX_OFFCPU_LEN 128 is too big, make it smaller.
> - Delete some bound check as it's always guaranteed
> - Do not set ip_pos in BPF
> - Add a new field for storing stack traces in the tstamp map
> - Dump the off-cpu sample directly or save it in the off_cpu map, not both
> - Delete the sample_type_off_cpu check
> - Use __set_off_cpu_sample() to parse samples instead of a two-pass parsing
>
> Changes in v6:
> - Make patches bisectable
>
> Changes in v5:
> - Delete unnecessary copy in BPF program
> - Remove sample_embed from perf header, hard code off-cpu stuff instead
> - Move evsel__is_offcpu_event() to evsel.h
> - Minor changes to the test
> - Edit some comments
>
> Changes in v4:
> - Minimize the size of data output by perf_event_output()
> - Keep only one off-cpu event
> - Change off-cpu threshold's unit to microseconds
> - Set a default off-cpu threshold
> - Print the correct error message for the field 'embed' in perf data header
>
> Changes in v3:
> - Add off-cpu-thresh argument
> - Process direct off-cpu samples in post
>
> Changes in v2:
> - Remove unnecessary comments.
> - Rename function off_cpu_change_type to off_cpu_prepare_parse
>
> v1:
>
> As mentioned in: https://bugzilla.kernel.org/show_bug.cgi?id=207323
>
> Currently, off-cpu samples are dumped when perf record is exiting. This
> results in off-cpu samples being after the regular samples. This patch
> series makes possible dumping off-cpu samples on-the-fly, directly into
> perf ring buffer. And it dispatches those samples to the correct format
> for perf.data consumers.
>
> Before:
> ```
> migration/0 21 [000] 27981.041319: 2944637851 cycles:P: ffffffff90d2e8aa record_times+0xa ([kernel.kallsyms])
> perf 770116 [001] 27981.041375: 1 cycles:P: ffffffff90ee4960 event_function+0xf0 ([kernel.kallsyms])
> perf 770116 [001] 27981.041377: 1 cycles:P: ffffffff90c184b1 intel_bts_enable_local+0x31 ([kernel.kallsyms])
> perf 770116 [001] 27981.041379: 51611 cycles:P: ffffffff91a160b0 native_sched_clock+0x30 ([kernel.kallsyms])
> migration/1 26 [001] 27981.041400: 4227682775 cycles:P: ffffffff90d06a74 wakeup_preempt+0x44 ([kernel.kallsyms])
> migration/2 32 [002] 27981.041477: 4159401534 cycles:P: ffffffff90d11993 update_load_avg+0x63 ([kernel.kallsyms])
>
> sshd 708098 [000] 18446744069.414584: 286392 offcpu-time:
> 79a864f1c8bb ppoll+0x4b (/usr/lib/libc.so.6)
> 585690935cca [unknown] (/usr/bin/sshd)
> ```
>
> After:
> ```
> perf 774767 [003] 28178.033444: 497 cycles:P: ffffffff91a160c3 native_sched_clock+0x43 ([kernel.kallsyms])
> perf 774767 [003] 28178.033445: 399440 cycles:P: ffffffff91c01f8d nmi_restore+0x25 ([kernel.kallsyms])
> swapper 0 [001] 28178.036639: 376650973 cycles:P: ffffffff91a1ae99 intel_idle+0x59 ([kernel.kallsyms])
> swapper 0 [003] 28178.182921: 348779378 cycles:P: ffffffff91a1ae99 intel_idle+0x59 ([kernel.kallsyms])
> blueman-tray 1355 [000] 28178.627906: 100184571 offcpu-time:
> 7528eef1c39d __poll+0x4d (/usr/lib/libc.so.6)
> 7528edf7d8fd [unknown] (/usr/lib/libglib-2.0.so.0.8000.2)
> 7528edf1af95 g_main_context_iteration+0x35 (/usr/lib/libglib-2.0.so.0.8000.2)
> 7528eda4ab86 g_application_run+0x1f6 (/usr/lib/libgio-2.0.so.0.8000.2)
> 7528ee6aa596 [unknown] (/usr/lib/libffi.so.8.1.4)
> 7fff24e862d8 [unknown] ([unknown])
>
>
> blueman-tray 1355 [000] 28178.728137: 100187539 offcpu-time:
> 7528eef1c39d __poll+0x4d (/usr/lib/libc.so.6)
> 7528edf7d8fd [unknown] (/usr/lib/libglib-2.0.so.0.8000.2)
> 7528edf1af95 g_main_context_iteration+0x35 (/usr/lib/libglib-2.0.so.0.8000.2)
> 7528eda4ab86 g_application_run+0x1f6 (/usr/lib/libgio-2.0.so.0.8000.2)
> 7528ee6aa596 [unknown] (/usr/lib/libffi.so.8.1.4)
> 7fff24e862d8 [unknown] ([unknown])
>
>
> swapper 0 [000] 28178.463253: 195945410 cycles:P: ffffffff91a1ae99 intel_idle+0x59 ([kernel.kallsyms])
> dbus-broker 412 [002] 28178.464855: 376737008 cycles:P: ffffffff91c000a0 entry_SYSCALL_64+0x20 ([kernel.kallsyms])
> ```
>
> Howard Chu (10):
> perf record --off-cpu: Add --off-cpu-thresh option
> perf evsel: Expose evsel__is_offcpu_event() for future use
> perf record --off-cpu: Parse off-cpu event
> perf record --off-cpu: Preparation of off-cpu BPF program
> perf record --off-cpu: Dump off-cpu samples in BPF
> perf evsel: Assemble offcpu samples
> perf record --off-cpu: Disable perf_event's callchain collection
> perf script: Display off-cpu samples correctly
> perf record --off-cpu: Dump the remaining samples in BPF's stack trace
> map
> perf test: Add direct off-cpu test
>
> tools/perf/builtin-record.c | 26 ++++++
> tools/perf/builtin-script.c | 4 +-
> tools/perf/tests/builtin-test.c | 1 +
> tools/perf/tests/shell/record_offcpu.sh | 35 ++++++-
> tools/perf/tests/tests.h | 1 +
> tools/perf/tests/workloads/Build | 1 +
> tools/perf/tests/workloads/offcpu.c | 16 ++++
> tools/perf/util/bpf_off_cpu.c | 117 ++++++++++++++----------
> tools/perf/util/bpf_skel/off_cpu.bpf.c | 97 +++++++++++++++++++-
> tools/perf/util/evsel.c | 34 ++++++-
> tools/perf/util/evsel.h | 2 +
> tools/perf/util/off_cpu.h | 3 +-
> tools/perf/util/record.h | 1 +
> 13 files changed, 282 insertions(+), 56 deletions(-)
> create mode 100644 tools/perf/tests/workloads/offcpu.c
>
> --
> 2.43.0
>
^ permalink raw reply [flat|nested] 18+ messages in thread