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Date: Mon, 21 Oct 2019 19:51:17 +0800
From: Jiwei Sun <Jiwei.Sun@...driver.com>
To: <acme@...hat.com>, <jolsa@...hat.com>, <arnaldo.melo@...il.com>,
<linux-kernel@...r.kernel.org>
CC: <alexander.shishkin@...ux.intel.com>, <mpetlan@...hat.com>,
<namhyung@...nel.org>, <a.p.zijlstra@...llo.nl>,
<adrian.hunter@...el.com>, <Richard.Danter@...driver.com>
Subject: Re: [PATCH v4] perf record: Add support for limit perf output file
size
Hello Arnaldo & Jirka,
Do you have any other suggestions regarding the patch?
Any suggestions are welcome. Thank you very much.
Regards,
Jiwei
On 2019e9409f..25f.% 15:06, Jiwei Sun wrote:
> The patch adds a new option to limit the output file size, then based
> on it, we can create a wrapper of the perf command that uses the option
> to avoid exhausting the disk space by the unconscious user.
>
> In order to make the perf.data parsable, we just limit the sample data
> size, since the perf.data consists of many headers and sample data and
> other data, the actual size of the recorded file will bigger than the
> setting value.
>
> Testing it:
>
> # ./perf record -a -g --max-size=10M
> Couldn't synthesize bpf events.
> WARNING: The perf data has already reached the limit, stop recording!
> [ perf record: Woken up 30 times to write data ]
> [ perf record: Captured and wrote 10.233 MB perf.data (175650 samples) ]
> Terminated
>
> # ls -lh perf.data
> -rw------- 1 root root 11M Jul 17 14:01 perf.data
>
> # ./perf record -a -g --max-size=10K
> WARNING: The perf data has already reached the limit, stop recording!
> Couldn't synthesize bpf events.
> [ perf record: Woken up 0 times to write data ]
> [ perf record: Captured and wrote 1.824 MB perf.data (67 samples) ]
> Terminated
>
> # ls -lh perf.data
> -rw------- 1 root root 1.9M Jul 17 14:05 perf.data
>
> Signed-off-by: Jiwei Sun <jiwei.sun@...driver.com>
> ---
> v4 changes:
> - Just show one WARNING message after reached the limit.
>
> v3 changes:
> - add a test result
> - add the new option to tools/perf/Documentation/perf-record.txt
>
> v2 changes:
> - make patch based on latest Arnaldo's perf/core,
> - display warning message when reached the limit.
> ---
> tools/perf/Documentation/perf-record.txt | 4 +++
> tools/perf/builtin-record.c | 42 ++++++++++++++++++++++++
> 2 files changed, 46 insertions(+)
>
> diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt
> index c6f9f31b6039..f1c6113fbc82 100644
> --- a/tools/perf/Documentation/perf-record.txt
> +++ b/tools/perf/Documentation/perf-record.txt
> @@ -571,6 +571,10 @@ config terms. For example: 'cycles/overwrite/' and 'instructions/no-overwrite/'.
>
> Implies --tail-synthesize.
>
> +--max-size=<size>::
> +Limit the sample data max size, <size> is expected to be a number with
> +appended unit character - B/K/M/G
> +
> 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 48600c90cc7e..30904d2a3407 100644
> --- a/tools/perf/builtin-record.c
> +++ b/tools/perf/builtin-record.c
> @@ -91,6 +91,7 @@ struct record {
> struct switch_output switch_output;
> unsigned long long samples;
> cpu_set_t affinity_mask;
> + unsigned long output_max_size; /* = 0: unlimited */
> };
>
> static volatile int auxtrace_record__snapshot_started;
> @@ -120,6 +121,12 @@ static bool switch_output_time(struct record *rec)
> trigger_is_ready(&switch_output_trigger);
> }
>
> +static bool record__output_max_size_exceeded(struct record *rec)
> +{
> + return rec->output_max_size &&
> + (rec->bytes_written >= rec->output_max_size);
> +}
> +
> static int record__write(struct record *rec, struct mmap *map __maybe_unused,
> void *bf, size_t size)
> {
> @@ -132,6 +139,12 @@ static int record__write(struct record *rec, struct mmap *map __maybe_unused,
>
> rec->bytes_written += size;
>
> + if (record__output_max_size_exceeded(rec)) {
> + WARN_ONCE(1, "WARNING: The perf data has already reached "
> + "the limit, stop recording!\n");
> + raise(SIGTERM);
> + }
> +
> if (switch_output_size(rec))
> trigger_hit(&switch_output_trigger);
>
> @@ -1936,6 +1949,33 @@ static int record__parse_affinity(const struct option *opt, const char *str, int
> return 0;
> }
>
> +static int parse_output_max_size(const struct option *opt,
> + const char *str, int unset)
> +{
> + unsigned long *s = (unsigned long *)opt->value;
> + 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 (unset) {
> + *s = 0;
> + return 0;
> + }
> +
> + val = parse_tag_value(str, tags_size);
> + if (val != (unsigned long) -1) {
> + *s = val;
> + return 0;
> + }
> +
> + return -1;
> +}
> +
> static int record__parse_mmap_pages(const struct option *opt,
> const char *str,
> int unset __maybe_unused)
> @@ -2262,6 +2302,8 @@ static struct option __record_options[] = {
> "n", "Compressed records using specified level (default: 1 - fastest compression, 22 - greatest compression)",
> record__parse_comp_level),
> #endif
> + OPT_CALLBACK(0, "max-size", &record.output_max_size,
> + "size", "Limit the maximum size of the output file", parse_output_max_size),
> OPT_END()
> };
>
>
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