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Message-ID: <20240424024805.144759-2-howardchu95@gmail.com>
Date: Wed, 24 Apr 2024 10:48:02 +0800
From: Howard Chu <howardchu95@...il.com>
To: peterz@...radead.org
Cc: mingo@...hat.com,
acme@...nel.org,
namhyung@...nel.org,
mark.rutland@....com,
alexander.shishkin@...ux.intel.com,
jolsa@...nel.org,
irogers@...gle.com,
adrian.hunter@...el.com,
kan.liang@...ux.intel.com,
zegao2021@...il.com,
leo.yan@...ux.dev,
ravi.bangoria@....com,
linux-perf-users@...r.kernel.org,
linux-kernel@...r.kernel.org,
bpf@...r.kernel.org
Subject: [PATCH v2 1/4] perf record off-cpu: Parse off-cpu event, change config location
Parse off-cpu events using parse_event(). Change the location of
record__config_off_cpu, after record__open because we need to write
mmapped fds into BPF's perf_event_array map, also, write
sample_id/sample_type into BPF. In record__pushfn and record__aio_pushfn,
handle off-cpu samples by off_cpu_strip. This is because the off-cpu
samples that we want to write to perf.data is in off-cpu samples' raw_data
section:
regular samples:
[sample: sample_data]
off-cpu samples:
[sample: [raw_data: sample_data]]
We need to extract the useful sample data out before writing.
Hooks record_done just before evlist__disable to stop BPF program from
outputting, otherwise, we lose some samples.
After samples are collected, change sample_type of off-cpu event to
the OFFCPU_SAMPLE_TYPES for parsing correctly, it was PERF_SAMPLE_RAW and
some others, because BPF can only output to a specific type of perf_event,
which is why `evsel->core.attr.sample_type &= OFFCPU_SAMPLE_TYPES;` is
deleted in util/evsel.c.
Signed-off-by: Howard Chu <howardchu95@...il.com>
---
tools/perf/builtin-record.c | 98 ++++++++++++++++++++++++++++++++++---
tools/perf/util/evsel.c | 8 ---
2 files changed, 91 insertions(+), 15 deletions(-)
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 2ff718d3e202..3994adaf4607 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -389,6 +389,8 @@ struct record_aio {
static int record__aio_pushfn(struct mmap *map, void *to, void *buf, size_t size)
{
struct record_aio *aio = to;
+ char *bf_stripped = NULL;
+ size_t stripped;
/*
* map->core.base data pointed by buf is copied into free map->aio.data[] buffer
@@ -404,6 +406,31 @@ static int record__aio_pushfn(struct mmap *map, void *to, void *buf, size_t size
* from the beginning of the kernel buffer till the end of the data chunk.
*/
+ if (aio->rec->off_cpu) {
+ if (size == 0)
+ return 0;
+
+ map->core.start -= size;
+ size = map->core.end - map->core.start;
+
+ bf_stripped = malloc(size);
+
+ if (bf_stripped == NULL) {
+ pr_err("Failed to allocate off-cpu strip buffer\n");
+ return -ENOMEM;
+ }
+
+ stripped = off_cpu_strip(aio->rec->evlist, map, bf_stripped, size);
+
+ if (stripped < 0) {
+ size = (int)stripped;
+ goto out;
+ }
+
+ size = stripped;
+ buf = bf_stripped;
+ }
+
if (record__comp_enabled(aio->rec)) {
ssize_t compressed = zstd_compress(aio->rec->session, NULL, aio->data + aio->size,
mmap__mmap_len(map) - aio->size,
@@ -432,6 +459,9 @@ static int record__aio_pushfn(struct mmap *map, void *to, void *buf, size_t size
aio->size += size;
+out:
+ free(bf_stripped);
+
return size;
}
@@ -635,6 +665,38 @@ static int process_locked_synthesized_event(struct perf_tool *tool,
static int record__pushfn(struct mmap *map, void *to, void *bf, size_t size)
{
struct record *rec = to;
+ int err;
+ char *bf_stripped = NULL;
+ size_t stripped;
+
+ if (rec->off_cpu) {
+ /*
+ * We'll read all the events at once without masking.
+ * When reading the remainder from a map, the size is 0, because
+ * start is shifted to the end so no more data is to be read.
+ */
+ if (size == 0)
+ return 0;
+
+ map->core.start -= size;
+ /* size in total */
+ size = map->core.end - map->core.start;
+
+ bf_stripped = malloc(size);
+
+ if (bf_stripped == NULL) {
+ pr_err("Failed to allocate off-cpu strip buffer\n");
+ return -ENOMEM;
+ }
+
+ stripped = off_cpu_strip(rec->evlist, map, bf_stripped, size);
+
+ if (stripped < 0)
+ return (int)stripped;
+
+ size = stripped;
+ bf = bf_stripped;
+ }
if (record__comp_enabled(rec)) {
ssize_t compressed = zstd_compress(rec->session, map, map->data,
@@ -648,7 +710,11 @@ static int record__pushfn(struct mmap *map, void *to, void *bf, size_t size)
}
thread->samples++;
- return record__write(rec, map, bf, size);
+ err = record__write(rec, map, bf, size);
+
+ free(bf_stripped);
+
+ return err;
}
static volatile sig_atomic_t signr = -1;
@@ -1790,6 +1856,7 @@ record__finish_output(struct record *rec)
if (rec->buildid_all)
perf_session__dsos_hit_all(rec->session);
}
+
perf_session__write_header(rec->session, rec->evlist, fd, true);
return;
@@ -2501,6 +2568,14 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
}
}
+ if (rec->off_cpu) {
+ err = record__config_off_cpu(rec);
+ if (err) {
+ pr_err("record__config_off_cpu failed, error %d\n", err);
+ goto out_free_threads;
+ }
+ }
+
/*
* Normally perf_session__new would do this, but it doesn't have the
* evlist.
@@ -2764,6 +2839,7 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
* disable events in this case.
*/
if (done && !disabled && !target__none(&opts->target)) {
+ perf_hooks__invoke_record_done();
trigger_off(&auxtrace_snapshot_trigger);
evlist__disable(rec->evlist);
disabled = true;
@@ -2827,14 +2903,17 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
} else
status = err;
- if (rec->off_cpu)
- rec->bytes_written += off_cpu_write(rec->session);
-
record__read_lost_samples(rec);
record__synthesize(rec, true);
/* this will be recalculated during process_buildids() */
rec->samples = 0;
+ /* change to the correct sample type for parsing */
+ if (rec->off_cpu && off_cpu_prepare_parse(rec->evlist)) {
+ pr_err("ERROR: Failed to change sample type for off-cpu event\n");
+ goto out_delete_session;
+ }
+
if (!err) {
if (!rec->timestamp_filename) {
record__finish_output(rec);
@@ -3198,7 +3277,7 @@ static int switch_output_setup(struct record *rec)
unsigned long val;
/*
- * If we're using --switch-output-events, then we imply its
+ * If we're using --switch-output-events, then we imply its
* --switch-output=signal, as we'll send a SIGUSR2 from the side band
* thread to its parent.
*/
@@ -4221,9 +4300,14 @@ int cmd_record(int argc, const char **argv)
}
if (rec->off_cpu) {
- err = record__config_off_cpu(rec);
+ char off_cpu_event[64];
+
+ snprintf(off_cpu_event, sizeof(off_cpu_event),
+ "bpf-output/no-inherit=1,name=%s/", OFFCPU_EVENT);
+
+ err = parse_event(rec->evlist, off_cpu_event);
if (err) {
- pr_err("record__config_off_cpu failed, error %d\n", err);
+ pr_err("Failed to open off-cpu event\n");
goto out;
}
}
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
index 3536404e9447..c08ae6a3c8d6 100644
--- a/tools/perf/util/evsel.c
+++ b/tools/perf/util/evsel.c
@@ -1092,11 +1092,6 @@ static void evsel__set_default_freq_period(struct record_opts *opts,
}
}
-static bool evsel__is_offcpu_event(struct evsel *evsel)
-{
- return evsel__is_bpf_output(evsel) && evsel__name_is(evsel, OFFCPU_EVENT);
-}
-
/*
* The enable_on_exec/disabled value strategy:
*
@@ -1363,9 +1358,6 @@ void evsel__config(struct evsel *evsel, struct record_opts *opts,
if (evsel__is_dummy_event(evsel))
evsel__reset_sample_bit(evsel, BRANCH_STACK);
- if (evsel__is_offcpu_event(evsel))
- evsel->core.attr.sample_type &= OFFCPU_SAMPLE_TYPES;
-
arch__post_evsel_config(evsel, attr);
}
--
2.44.0
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