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Subject[tip:perf/core] perf record: Add switch-output size option argument
Commit-ID:  dc0c6127c231d4d264570497a916fa19740c915b
Gitweb: http://git.kernel.org/tip/dc0c6127c231d4d264570497a916fa19740c915b
Author: Jiri Olsa <jolsa@kernel.org>
AuthorDate: Mon, 9 Jan 2017 10:51:58 +0100
Committer: Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Wed, 11 Jan 2017 16:48:02 -0300

perf record: Add switch-output size option argument

It's now possible to specify the threshold size for perf.data like:

$ perf record --switch-output=2G ...

Once it's reached, the current data are dumped in to the
perf.data.<timestamp> file and session does on.

$ perf record --switch-output=2G ...
[ perf record: dump data: Woken up 7244 times ]
[ perf record: Dump perf.data.2017010214093746 ]
...

The size is expected to be a number with appended unit character -
B/K/M/G.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Wang Nan <wangnan0@huawei.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1483955520-29063-5-git-send-email-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/Documentation/perf-record.txt | 12 +++++-
tools/perf/builtin-record.c | 67 +++++++++++++++++++++++++-------
2 files changed, 63 insertions(+), 16 deletions(-)

diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt
index 5054d91..3d55d2f 100644
--- a/tools/perf/Documentation/perf-record.txt
+++ b/tools/perf/Documentation/perf-record.txt
@@ -421,9 +421,17 @@ Configure all used events to run in user space.
--timestamp-filename
Append timestamp to output file name.

---switch-output::
+--switch-output[=mode]::
Generate multiple perf.data files, timestamp prefixed, switching to a new one
-when receiving a SIGUSR2.
+based on 'mode' value:
+ "signal" - when receiving a SIGUSR2 (default value) or
+ <size> - when reaching the size threshold, size is expected to
+ be a number with appended unit character - B/K/M/G
+
+ Note: the precision of the size threshold hugely depends
+ on your configuration - the number and size of your ring
+ buffers (-m). It is generally more precise for higher sizes
+ (like >5M), for lower values expect different sizes.

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
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 2bf811a..3fa6449 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -47,7 +47,9 @@
#include <linux/time64.h>

struct switch_output {
+ bool enabled;
bool signal;
+ unsigned long size;
const char *str;
bool set;
};
@@ -72,6 +74,23 @@ struct record {
unsigned long long samples;
};

+static volatile int auxtrace_record__snapshot_started;
+static DEFINE_TRIGGER(auxtrace_snapshot_trigger);
+static DEFINE_TRIGGER(switch_output_trigger);
+
+static bool switch_output_signal(struct record *rec)
+{
+ return rec->switch_output.signal &&
+ trigger_is_ready(&switch_output_trigger);
+}
+
+static bool switch_output_size(struct record *rec)
+{
+ return rec->switch_output.size &&
+ trigger_is_ready(&switch_output_trigger) &&
+ (rec->bytes_written >= rec->switch_output.size);
+}
+
static int record__write(struct record *rec, void *bf, size_t size)
{
if (perf_data_file__write(rec->session->file, bf, size) < 0) {
@@ -80,6 +99,10 @@ static int record__write(struct record *rec, void *bf, size_t size)
}

rec->bytes_written += size;
+
+ if (switch_output_size(rec))
+ trigger_hit(&switch_output_trigger);
+
return 0;
}

@@ -199,10 +222,6 @@ static volatile int done;
static volatile int signr = -1;
static volatile int child_finished;

-static volatile int auxtrace_record__snapshot_started;
-static DEFINE_TRIGGER(auxtrace_snapshot_trigger);
-static DEFINE_TRIGGER(switch_output_trigger);
-
static void sig_handler(int sig)
{
if (sig == SIGCHLD)
@@ -848,11 +867,11 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
signal(SIGTERM, sig_handler);
signal(SIGSEGV, sigsegv_handler);

- if (rec->opts.auxtrace_snapshot_mode || rec->switch_output.signal) {
+ if (rec->opts.auxtrace_snapshot_mode || rec->switch_output.enabled) {
signal(SIGUSR2, snapshot_sig_handler);
if (rec->opts.auxtrace_snapshot_mode)
trigger_on(&auxtrace_snapshot_trigger);
- if (rec->switch_output.signal)
+ if (rec->switch_output.enabled)
trigger_on(&switch_output_trigger);
} else {
signal(SIGUSR2, SIG_IGN);
@@ -1361,6 +1380,14 @@ out_free:
static int switch_output_setup(struct record *rec)
{
struct switch_output *s = &rec->switch_output;
+ static struct parse_tag tags_size[] = {
+ { .tag = 'B', .mult = 1 },
+ { .tag = 'K', .mult = 1 << 10 },
+ { .tag = 'M', .mult = 1 << 20 },
+ { .tag = 'G', .mult = 1 << 30 },
+ { .tag = 0 },
+ };
+ unsigned long val;

if (!s->set)
return 0;
@@ -1368,10 +1395,22 @@ static int switch_output_setup(struct record *rec)
if (!strcmp(s->str, "signal")) {
s->signal = true;
pr_debug("switch-output with SIGUSR2 signal\n");
- return 0;
+ goto enabled;
+ }
+
+ val = parse_tag_value(s->str, tags_size);
+ if (val != (unsigned long) -1) {
+ s->size = val;
+ pr_debug("switch-output with %s size threshold\n", s->str);
+ goto enabled;
}

return -1;
+
+enabled:
+ rec->timestamp_filename = true;
+ s->enabled = true;
+ return 0;
}

static const char * const __record_usage[] = {
@@ -1542,8 +1581,9 @@ static struct option __record_options[] = {
OPT_BOOLEAN(0, "timestamp-filename", &record.timestamp_filename,
"append timestamp to output filename"),
OPT_STRING_OPTARG_SET(0, "switch-output", &record.switch_output.str,
- &record.switch_output.set, "signal",
- "Switch output when receive SIGUSR2", "signal"),
+ &record.switch_output.set, "signal,size",
+ "Switch output when receive SIGUSR2 or cross size threshold",
+ "signal"),
OPT_BOOLEAN(0, "dry-run", &dry_run,
"Parse options then exit"),
OPT_END()
@@ -1606,9 +1646,6 @@ int cmd_record(int argc, const char **argv, const char *prefix __maybe_unused)
return -EINVAL;
}

- if (rec->switch_output.signal)
- rec->timestamp_filename = true;
-
if (!rec->itr) {
rec->itr = auxtrace_record__init(rec->evlist, &err);
if (err)
@@ -1657,7 +1694,7 @@ int cmd_record(int argc, const char **argv, const char *prefix __maybe_unused)

if (rec->no_buildid_cache || rec->no_buildid) {
disable_buildid_cache();
- } else if (rec->switch_output.signal) {
+ } else if (rec->switch_output.enabled) {
/*
* In 'perf record --switch-output', disable buildid
* generation by default to reduce data file switching
@@ -1749,6 +1786,8 @@ out:

static void snapshot_sig_handler(int sig __maybe_unused)
{
+ struct record *rec = &record;
+
if (trigger_is_ready(&auxtrace_snapshot_trigger)) {
trigger_hit(&auxtrace_snapshot_trigger);
auxtrace_record__snapshot_started = 1;
@@ -1756,6 +1795,6 @@ static void snapshot_sig_handler(int sig __maybe_unused)
trigger_error(&auxtrace_snapshot_trigger);
}

- if (trigger_is_ready(&switch_output_trigger))
+ if (switch_output_signal(rec))
trigger_hit(&switch_output_trigger);
}
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