Date:   Mon, 21 Oct 2019 13:55:46 +0200
From:   Jiri Olsa <jolsa@...hat.com>
To:     Jiwei Sun <Jiwei.Sun@...driver.com>
Cc:     acme@...hat.com, arnaldo.melo@...il.com,
        linux-kernel@...r.kernel.org, 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

On Mon, Oct 21, 2019 at 07:51:17PM +0800, Jiwei Sun wrote:
> Hello Arnaldo & Jirka,
> 
> Do you have any other suggestions regarding the patch? 
> Any suggestions are welcome. Thank you very much.

oops, overlooked this one, sry..  I'll check on it today

jirka

> 
> 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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