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Subject[PATCH 18/28] perf record: Add an option to take an AUX snapshot on exit
Date
From: Alexander Shishkin <alexander.shishkin@linux.intel.com>

It is sometimes useful to generate a snapshot when perf record exits;
I've been using a wrapper script around the workload that would do a
killall -USR2 perf when the workload exits.

This patch makes it easier and also works when perf record is attached
to a pre-existing task. A new snapshot option 'e' can be specified in
-S to enable this behavior:

root@elsewhere:~# perf record -e intel_pt// -Se sleep 1
[ perf record: Woken up 2 times to write data ]
[ perf record: Captured and wrote 0.085 MB perf.data ]

Co-developed-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20190806144101.62892-1-alexander.shishkin@linux.intel.com
[ Fixed up !HAVE_AUXTRACE_SUPPORT build in builtin-record.c, adding 2 missing __maybe_unused ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/Documentation/perf-record.txt | 11 ++++++--
tools/perf/builtin-record.c | 35 +++++++++++++++++++++---
tools/perf/perf.h | 1 +
tools/perf/util/auxtrace.c | 14 ++++++++--
tools/perf/util/auxtrace.h | 2 +-
5 files changed, 53 insertions(+), 10 deletions(-)

diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt
index 15e0fa87241b..d5e58e0a2bca 100644
--- a/tools/perf/Documentation/perf-record.txt
+++ b/tools/perf/Documentation/perf-record.txt
@@ -422,9 +422,14 @@ CLOCK_BOOTTIME, CLOCK_REALTIME and CLOCK_TAI.
-S::
--snapshot::
Select AUX area tracing Snapshot Mode. This option is valid only with an
-AUX area tracing event. Optionally the number of bytes to capture per
-snapshot can be specified. In Snapshot Mode, trace data is captured only when
-signal SIGUSR2 is received.
+AUX area tracing event. Optionally, certain snapshot capturing parameters
+can be specified in a string that follows this option:
+ 'e': take one last snapshot on exit; guarantees that there is at least one
+ snapshot in the output file;
+ <size>: if the PMU supports this, specify the desired snapshot size.
+
+In Snapshot Mode trace data is captured only when signal SIGUSR2 is received
+and on exit if the above 'e' option is given.

--proc-map-timeout::
When processing pre-existing threads /proc/XXX/mmap, it may take a long time,
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index d31d7a5a1be3..f71631f2bcb5 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -613,19 +613,35 @@ static int record__auxtrace_read_snapshot_all(struct record *rec)
return rc;
}

-static void record__read_auxtrace_snapshot(struct record *rec)
+static void record__read_auxtrace_snapshot(struct record *rec, bool on_exit)
{
pr_debug("Recording AUX area tracing snapshot\n");
if (record__auxtrace_read_snapshot_all(rec) < 0) {
trigger_error(&auxtrace_snapshot_trigger);
} else {
- if (auxtrace_record__snapshot_finish(rec->itr))
+ if (auxtrace_record__snapshot_finish(rec->itr, on_exit))
trigger_error(&auxtrace_snapshot_trigger);
else
trigger_ready(&auxtrace_snapshot_trigger);
}
}

+static int record__auxtrace_snapshot_exit(struct record *rec)
+{
+ if (trigger_is_error(&auxtrace_snapshot_trigger))
+ return 0;
+
+ if (!auxtrace_record__snapshot_started &&
+ auxtrace_record__snapshot_start(rec->itr))
+ return -1;
+
+ record__read_auxtrace_snapshot(rec, true);
+ if (trigger_is_error(&auxtrace_snapshot_trigger))
+ return -1;
+
+ return 0;
+}
+
static int record__auxtrace_init(struct record *rec)
{
int err;
@@ -654,7 +670,8 @@ int record__auxtrace_mmap_read(struct record *rec __maybe_unused,
}

static inline
-void record__read_auxtrace_snapshot(struct record *rec __maybe_unused)
+void record__read_auxtrace_snapshot(struct record *rec __maybe_unused,
+ bool on_exit __maybe_unused)
{
}

@@ -664,6 +681,12 @@ int auxtrace_record__snapshot_start(struct auxtrace_record *itr __maybe_unused)
return 0;
}

+static inline
+int record__auxtrace_snapshot_exit(struct record *rec __maybe_unused)
+{
+ return 0;
+}
+
static int record__auxtrace_init(struct record *rec __maybe_unused)
{
return 0;
@@ -1536,7 +1559,7 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
if (auxtrace_record__snapshot_started) {
auxtrace_record__snapshot_started = 0;
if (!trigger_is_error(&auxtrace_snapshot_trigger))
- record__read_auxtrace_snapshot(rec);
+ record__read_auxtrace_snapshot(rec, false);
if (trigger_is_error(&auxtrace_snapshot_trigger)) {
pr_err("AUX area tracing snapshot failed\n");
err = -1;
@@ -1609,9 +1632,13 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
disabled = true;
}
}
+
trigger_off(&auxtrace_snapshot_trigger);
trigger_off(&switch_output_trigger);

+ if (opts->auxtrace_snapshot_on_exit)
+ record__auxtrace_snapshot_exit(rec);
+
if (forks && workload_exec_errno) {
char msg[STRERR_BUFSIZE];
const char *emsg = str_error_r(workload_exec_errno, msg, sizeof(msg));
diff --git a/tools/perf/perf.h b/tools/perf/perf.h
index 74d0124d38f3..dc0a7a237887 100644
--- a/tools/perf/perf.h
+++ b/tools/perf/perf.h
@@ -57,6 +57,7 @@ struct record_opts {
bool running_time;
bool full_auxtrace;
bool auxtrace_snapshot_mode;
+ bool auxtrace_snapshot_on_exit;
bool record_namespaces;
bool record_switch_events;
bool all_kernel;
diff --git a/tools/perf/util/auxtrace.c b/tools/perf/util/auxtrace.c
index 65728cdeefb6..72ce4c5e7c78 100644
--- a/tools/perf/util/auxtrace.c
+++ b/tools/perf/util/auxtrace.c
@@ -539,9 +539,9 @@ int auxtrace_record__snapshot_start(struct auxtrace_record *itr)
return 0;
}

-int auxtrace_record__snapshot_finish(struct auxtrace_record *itr)
+int auxtrace_record__snapshot_finish(struct auxtrace_record *itr, bool on_exit)
{
- if (itr && itr->snapshot_finish)
+ if (!on_exit && itr && itr->snapshot_finish)
return itr->snapshot_finish(itr);
return 0;
}
@@ -577,6 +577,16 @@ int auxtrace_parse_snapshot_options(struct auxtrace_record *itr,
if (!str)
return 0;

+ /* PMU-agnostic options */
+ switch (*str) {
+ case 'e':
+ opts->auxtrace_snapshot_on_exit = true;
+ str++;
+ break;
+ default:
+ break;
+ }
+
if (itr)
return itr->parse_snapshot_options(itr, opts, str);

diff --git a/tools/perf/util/auxtrace.h b/tools/perf/util/auxtrace.h
index 17eb04a1da4d..8ccabacd0b11 100644
--- a/tools/perf/util/auxtrace.h
+++ b/tools/perf/util/auxtrace.h
@@ -499,7 +499,7 @@ int auxtrace_record__info_fill(struct auxtrace_record *itr,
size_t priv_size);
void auxtrace_record__free(struct auxtrace_record *itr);
int auxtrace_record__snapshot_start(struct auxtrace_record *itr);
-int auxtrace_record__snapshot_finish(struct auxtrace_record *itr);
+int auxtrace_record__snapshot_finish(struct auxtrace_record *itr, bool on_exit);
int auxtrace_record__find_snapshot(struct auxtrace_record *itr, int idx,
struct auxtrace_mmap *mm,
unsigned char *data, u64 *head, u64 *old);
--
2.21.0
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