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Message-ID: <20240422083934.1934290-1-howardchu95@gmail.com>
Date: Mon, 22 Apr 2024 16:39:34 +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,
Howard Chu <howardchu95@...il.com>
Subject: [PATCH v1 3/4] perf record: Dump off-cpu samples directly
Because we need to extract real sample data from raw_data, an
off_cpu_strip function is needed. In off_cpu_strip, we read events one by
one, stripping actual samples from raw data. After stripping is done, a
stripped buffer will be written to the perf.data(or compressed).
The size is end - start without masking, because masking will be handled
by perf_mmap__read_event(). Also, there's no need to call
perf_mmap__consume() as it will be called in perf_mmap__push(). We read
all the data at once, so start will be moved to end, when
perf_mmap__push() is called in pushfn the second time, size will be zero,
just returns directly.
Hook record_done instead of record_end to off_cpu_finish.
Although moving record_end hook is also fine because currently, only
off-cpu is using these hooks, technically record doesn't end when we need
to turn off BPF output, so it may confuse if moved. The reason why there's
an additional off_cpu_change_type is that it cannot be put into
off_cpu_finish because there are still samples to be read(which requires
sample_type to stay PERF_SAMPLE_RAW), and it cannot be hooked to
record_end because it has to be put before record__finish_output.
Signed-off-by: Howard Chu <howardchu95@...il.com>
---
tools/perf/util/bpf_off_cpu.c | 245 +++++++++++++-----------------
tools/perf/util/off_cpu.h | 14 +-
tools/perf/util/perf-hooks-list.h | 1 +
3 files changed, 121 insertions(+), 139 deletions(-)
diff --git a/tools/perf/util/bpf_off_cpu.c b/tools/perf/util/bpf_off_cpu.c
index 6af36142dc5a..df1f02938099 100644
--- a/tools/perf/util/bpf_off_cpu.c
+++ b/tools/perf/util/bpf_off_cpu.c
@@ -12,6 +12,9 @@
#include "util/thread_map.h"
#include "util/cgroup.h"
#include "util/strlist.h"
+#include "util/mmap.h"
+#include "util/sample.h"
+#include <perf/mmap.h>
#include <bpf/bpf.h>
#include "bpf_skel/off_cpu.skel.h"
@@ -23,51 +26,6 @@
static struct off_cpu_bpf *skel;
-struct off_cpu_key {
- u32 pid;
- u32 tgid;
- u32 stack_id;
- u32 state;
- u64 cgroup_id;
-};
-
-union off_cpu_data {
- struct perf_event_header hdr;
- u64 array[1024 / sizeof(u64)];
-};
-
-static int off_cpu_config(struct evlist *evlist)
-{
- 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;
- }
-
- 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;
-
- return 0;
-}
-
static void off_cpu_start(void *arg)
{
struct evlist *evlist = arg;
@@ -125,18 +83,29 @@ static void check_sched_switch_args(void)
btf__free(btf);
}
+int off_cpu_change_type(struct evlist *evlist)
+{
+ struct evsel *evsel;
+
+ evsel = evlist__find_evsel_by_str(evlist, OFFCPU_EVENT);
+ if (evsel == NULL)
+ return -1;
+
+ evsel->core.attr.sample_type = OFFCPU_SAMPLE_TYPES;
+
+ return 0;
+}
+
int off_cpu_prepare(struct evlist *evlist, struct target *target,
struct record_opts *opts)
{
int err, fd, i;
int ncpus = 1, ntasks = 1, ncgrps = 1;
+ u64 sid = 0;
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");
- return -1;
- }
+ struct evsel *evsel;
+ struct perf_cpu pcpu;
skel = off_cpu_bpf__open();
if (!skel) {
@@ -250,7 +219,6 @@ int off_cpu_prepare(struct evlist *evlist, struct target *target,
}
if (evlist__first(evlist)->cgrp) {
- struct evsel *evsel;
u8 val = 1;
skel->bss->has_cgroup = 1;
@@ -272,6 +240,25 @@ int off_cpu_prepare(struct evlist *evlist, struct target *target,
}
}
+ evsel = evlist__find_evsel_by_str(evlist, OFFCPU_EVENT);
+ if (evsel == NULL) {
+ pr_err("%s evsel not found\n", OFFCPU_EVENT);
+ goto out;
+ }
+
+ if (evsel->core.id)
+ sid = evsel->core.id[0];
+
+ skel->bss->sample_id = sid;
+ skel->bss->sample_type = OFFCPU_SAMPLE_TYPES;
+
+ perf_cpu_map__for_each_cpu(pcpu, i, evsel->core.cpus) {
+ bpf_map__update_elem(skel->maps.offcpu_output,
+ &pcpu.cpu, sizeof(int),
+ xyarray__entry(evsel->core.fd, pcpu.cpu, 0),
+ sizeof(__u32), BPF_ANY);
+ }
+
err = off_cpu_bpf__attach(skel);
if (err) {
pr_err("Failed to attach off-cpu BPF skeleton\n");
@@ -279,7 +266,7 @@ int off_cpu_prepare(struct evlist *evlist, struct target *target,
}
if (perf_hooks__set_hook("record_start", off_cpu_start, evlist) ||
- perf_hooks__set_hook("record_end", off_cpu_finish, evlist)) {
+ perf_hooks__set_hook("record_done", off_cpu_finish, evlist)) {
pr_err("Failed to attach off-cpu skeleton\n");
goto out;
}
@@ -291,105 +278,91 @@ int off_cpu_prepare(struct evlist *evlist, struct target *target,
return -1;
}
-int off_cpu_write(struct perf_session *session)
+ssize_t off_cpu_strip(struct evlist *evlist, struct mmap *mp, char *dst, size_t size)
{
- int bytes = 0, size;
- int fd, stack;
- u64 sample_type, val, sid = 0;
+ /*
+ * In this function, we read events one by one,
+ * stripping actual samples from raw data.
+ * The size is end - start without masking,
+ * because masking will be handled by
+ * perf_mmap__read_event()
+ */
+
+ union perf_event *event, tmp;
+ u64 sample_type = OFFCPU_SAMPLE_TYPES;
+ size_t written = 0, event_sz, write_sz, raw_sz_aligned, offset = 0;
+ void *src;
+ int err = 0, n = 0;
+ struct perf_sample sample;
struct evsel *evsel;
- struct perf_data_file *file = &session->data->file;
- struct off_cpu_key prev, key;
- union off_cpu_data data = {
- .hdr = {
- .type = PERF_RECORD_SAMPLE,
- .misc = PERF_RECORD_MISC_USER,
- },
- };
- u64 tstamp = OFF_CPU_TIMESTAMP;
-
- skel->bss->enabled = 0;
- evsel = evlist__find_evsel_by_str(session->evlist, OFFCPU_EVENT);
+ evsel = evlist__find_evsel_by_str(evlist, OFFCPU_EVENT);
if (evsel == NULL) {
pr_err("%s evsel not found\n", OFFCPU_EVENT);
- return 0;
- }
-
- sample_type = evsel->core.attr.sample_type;
-
- if (sample_type & ~OFFCPU_SAMPLE_TYPES) {
- pr_err("not supported sample type: %llx\n",
- (unsigned long long)sample_type);
return -1;
}
- if (sample_type & (PERF_SAMPLE_ID | PERF_SAMPLE_IDENTIFIER)) {
- if (evsel->core.id)
- sid = evsel->core.id[0];
- }
+ /* for writing sample time*/
+ if (sample_type & PERF_SAMPLE_IDENTIFIER)
+ ++n;
+ if (sample_type & PERF_SAMPLE_IP)
+ ++n;
+ if (sample_type & PERF_SAMPLE_TID)
+ ++n;
+
+ /* no need for perf_mmap__consume(), it will be handled by perf_mmap__push() */
+ while ((event = perf_mmap__read_event(&mp->core)) != NULL) {
+ event_sz = event->header.size;
+ write_sz = event_sz;
+ src = event;
+
+ if (event->header.type == PERF_RECORD_SAMPLE) {
+ err = evlist__parse_sample(evlist, event, &sample);
+ if (err) {
+ pr_err("Failed to parse off-cpu sample\n");
+ return -1;
+ }
- fd = bpf_map__fd(skel->maps.off_cpu);
- stack = bpf_map__fd(skel->maps.stacks);
- memset(&prev, 0, sizeof(prev));
+ if (sample.raw_data && evsel->core.id) {
+ bool flag = false;
- while (!bpf_map_get_next_key(fd, &prev, &key)) {
- int n = 1; /* start from perf_event_header */
- int ip_pos = -1;
+ for (u32 i = 0; i < evsel->core.ids; i++) {
+ if (sample.id == evsel->core.id[i]) {
+ flag = true;
+ break;
+ }
+ }
+ if (flag) {
+ memcpy(&tmp, event, event_sz);
- bpf_map_lookup_elem(fd, &key, &val);
+ /* raw data has extra bits for alignment, discard them */
+ raw_sz_aligned = sample.raw_size - sizeof(u32);
+ memcpy(tmp.sample.array, sample.raw_data, raw_sz_aligned);
- if (sample_type & PERF_SAMPLE_IDENTIFIER)
- data.array[n++] = sid;
- if (sample_type & PERF_SAMPLE_IP) {
- ip_pos = n;
- data.array[n++] = 0; /* will be updated */
- }
- if (sample_type & PERF_SAMPLE_TID)
- data.array[n++] = (u64)key.pid << 32 | key.tgid;
- 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])
- len++;
-
- /* update length of callchain */
- data.array[n] = len + 1;
-
- /* update sample ip with the first callchain entry */
- if (ip_pos >= 0)
- data.array[ip_pos] = data.array[n + 2];
-
- /* calculate sample callchain data array length */
- n += len + 2;
- }
- if (sample_type & PERF_SAMPLE_CGROUP)
- data.array[n++] = key.cgroup_id;
+ write_sz = sizeof(struct perf_event_header) +
+ raw_sz_aligned;
+
+ /* without this we'll have out of order events */
+ if (sample_type & PERF_SAMPLE_TIME)
+ tmp.sample.array[n] = sample.time;
- size = n * sizeof(u64);
- data.hdr.size = size;
- bytes += size;
+ tmp.header.size = write_sz;
+ tmp.header.type = PERF_RECORD_SAMPLE;
+ tmp.header.misc = PERF_RECORD_MISC_USER;
- if (perf_data_file__write(file, &data, size) < 0) {
- pr_err("failed to write perf data, error: %m\n");
- return bytes;
+ src = &tmp;
+ }
+ }
}
+ if (offset + event_sz > size || written + write_sz > size)
+ break;
- prev = key;
- /* increase dummy timestamp to sort later samples */
- tstamp++;
+ memcpy(dst, src, write_sz);
+
+ dst += write_sz;
+ written += write_sz;
+ offset += event_sz;
}
- return bytes;
+
+ return written;
}
diff --git a/tools/perf/util/off_cpu.h b/tools/perf/util/off_cpu.h
index 2dd67c60f211..03d2f29cbb47 100644
--- a/tools/perf/util/off_cpu.h
+++ b/tools/perf/util/off_cpu.h
@@ -20,7 +20,9 @@ struct record_opts;
#ifdef HAVE_BPF_SKEL
int off_cpu_prepare(struct evlist *evlist, struct target *target,
struct record_opts *opts);
-int off_cpu_write(struct perf_session *session);
+ssize_t off_cpu_strip(struct evlist *evlist, struct mmap *mp,
+ char *dst, size_t size);
+int off_cpu_change_type(struct evlist *evlist);
#else
static inline int off_cpu_prepare(struct evlist *evlist __maybe_unused,
struct target *target __maybe_unused,
@@ -28,8 +30,14 @@ static inline int off_cpu_prepare(struct evlist *evlist __maybe_unused,
{
return -1;
}
-
-static inline int off_cpu_write(struct perf_session *session __maybe_unused)
+static inline ssize_t off_cpu_strip(struct evlist *evlist __maybe_unused,
+ struct mmap *mp __maybe_unused,
+ char *dst __maybe_unused,
+ size_t size __maybe_unused)
+{
+ return -1;
+}
+static inline int off_cpu_change_type(struct evlist *evlist __maybe_unused)
{
return -1;
}
diff --git a/tools/perf/util/perf-hooks-list.h b/tools/perf/util/perf-hooks-list.h
index 2867c07ee84e..1ce4d44ace35 100644
--- a/tools/perf/util/perf-hooks-list.h
+++ b/tools/perf/util/perf-hooks-list.h
@@ -1,3 +1,4 @@
PERF_HOOK(record_start)
PERF_HOOK(record_end)
+PERF_HOOK(record_done)
PERF_HOOK(test)
--
2.44.0
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