[PATCH v5 2/6] perf record: Split output into multiple files via '--switch-output'

From: Wang Nan
Date: Mon Apr 18 2016 - 10:57:56 EST


Allow 'perf record' to split its output into multiple files.

For example:

# ~/perf record -a --timestamp-filename --switch-output &
[1] 10763
# kill -s SIGUSR2 10763
[ perf record: dump data: Woken up 1 times ]
# [ perf record: Dump perf.data.2015122622314468 ]

# kill -s SIGUSR2 10763
[ perf record: dump data: Woken up 1 times ]
# [ perf record: Dump perf.data.2015122622314762 ]

# kill -s SIGUSR2 10763
[ perf record: dump data: Woken up 1 times ]
#[ perf record: Dump perf.data.2015122622315171 ]

# fg
perf record -a --timestamp-filename --switch-output
^C[ perf record: Woken up 1 times to write data ]
[ perf record: Dump perf.data.2015122622315513 ]
[ perf record: Captured and wrote 0.014 MB perf.data.<timestamp> (296 samples) ]

# ls -l
total 920
-rw------- 1 root root 797692 Dec 26 22:31 perf.data.2015122622314468
-rw------- 1 root root 59960 Dec 26 22:31 perf.data.2015122622314762
-rw------- 1 root root 59912 Dec 26 22:31 perf.data.2015122622315171
-rw------- 1 root root 19220 Dec 26 22:31 perf.data.2015122622315513

Signed-off-by: Wang Nan <wangnan0@xxxxxxxxxx>
Tested-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Zefan Li <lizefan@xxxxxxxxxx>
Cc: pi3orama@xxxxxxx
Link: http://lkml.kernel.org/r/1460643725-167413-3-git-send-email-wangnan0@xxxxxxxxxx
Signed-off-by: He Kuang <hekuang@xxxxxxxxxx>
[ Added man page entry ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
tools/perf/Documentation/perf-record.txt | 8 ++++++
tools/perf/builtin-record.c | 46 ++++++++++++++++++++++++++------
2 files changed, 46 insertions(+), 8 deletions(-)

diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt
index 19aa175..a77a431 100644
--- a/tools/perf/Documentation/perf-record.txt
+++ b/tools/perf/Documentation/perf-record.txt
@@ -347,6 +347,14 @@ Configure all used events to run in kernel space.
--all-user::
Configure all used events to run in user space.

+--switch-output::
+Generate multiple perf.data files, timestamp prefixed, switching to a new one
+when receiving a SIGUSR2.
+
+A possible use case is to, given an external event, slice the perf.data file
+that gets then processed, possibly via a perf script, to decide if that
+particular perf.data snapshot should be kept or not.
+
SEE ALSO
--------
linkperf:perf-stat[1], linkperf:perf-list[1]
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index ad37f69..07e57d9 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -58,6 +58,7 @@ struct record {
bool no_buildid_cache_set;
bool buildid_all;
bool timestamp_filename;
+ bool switch_output;
unsigned long long samples;
};

@@ -131,6 +132,8 @@ static volatile int child_finished;
static volatile int auxtrace_record__snapshot_started;
static DEFINE_TRIGGER(auxtrace_snapshot);

+static DEFINE_TRIGGER(switch_output);
+
static void sig_handler(int sig)
{
if (sig == SIGCHLD)
@@ -650,9 +653,12 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
signal(SIGINT, sig_handler);
signal(SIGTERM, sig_handler);

- if (rec->opts.auxtrace_snapshot_mode) {
+ if (rec->opts.auxtrace_snapshot_mode || rec->switch_output) {
signal(SIGUSR2, snapshot_sig_handler);
- auxtrace_snapshot_on();
+ if (rec->opts.auxtrace_snapshot_mode)
+ auxtrace_snapshot_on();
+ if (rec->switch_output)
+ switch_output_on();
} else {
signal(SIGUSR2, SIG_IGN);
}
@@ -782,11 +788,13 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
}

auxtrace_snapshot_ready();
+ switch_output_ready();
for (;;) {
unsigned long long hits = rec->samples;

if (record__mmap_read_all(rec) < 0) {
auxtrace_snapshot_error();
+ switch_output_error();
err = -1;
goto out_child;
}
@@ -802,6 +810,22 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
}
}

+ if (switch_output_is_toggled()) {
+ switch_output_ready();
+
+ if (!quiet)
+ fprintf(stderr, "[ perf record: dump data: Woken up %ld times ]\n",
+ waking);
+ waking = 0;
+ fd = record__switch_output(rec, false);
+ if (fd < 0) {
+ pr_err("Failed to switch to new file\n");
+ switch_output_error();
+ err = fd;
+ goto out_child;
+ }
+ }
+
if (hits == rec->samples) {
if (done || draining)
break;
@@ -830,6 +854,7 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
}
}
auxtrace_snapshot_off();
+ switch_output_off();

if (forks && workload_exec_errno) {
char msg[STRERR_BUFSIZE];
@@ -1265,6 +1290,8 @@ struct option __record_options[] = {
"Record build-id of all DSOs regardless of hits"),
OPT_BOOLEAN(0, "timestamp-filename", &record.timestamp_filename,
"append timestamp to output filename"),
+ OPT_BOOLEAN(0, "switch-output", &record.switch_output,
+ "Switch output when receive SIGUSR2"),
OPT_END()
};

@@ -1413,10 +1440,13 @@ out_symbol_exit:

static void snapshot_sig_handler(int sig __maybe_unused)
{
- if (!auxtrace_snapshot_is_ready())
- return;
- auxtrace_snapshot_toggle();
- auxtrace_record__snapshot_started = 1;
- if (auxtrace_record__snapshot_start(record.itr))
- auxtrace_snapshot_error();
+ if (auxtrace_snapshot_is_ready()) {
+ auxtrace_snapshot_toggle();
+ auxtrace_record__snapshot_started = 1;
+ if (auxtrace_record__snapshot_start(record.itr))
+ auxtrace_snapshot_error();
+ }
+
+ if (switch_output_is_ready())
+ switch_output_toggle();
}
--
1.8.3.4