linux-kernel - Re: [PATCH v4] perf record: Add support for limit perf output file size

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Date:   Tue, 22 Oct 2019 13:56:30 +0800
From:   Jiwei Sun <Jiwei.Sun@...driver.com>
To:     Jiri Olsa <jolsa@...hat.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

Hi Jirka,

On 2019e9410f..21f.% 21:41, Jiri Olsa wrote:
> On Wed, Sep 25, 2019 at 03:06:37PM +0800, Jiwei Sun wrote:
> 
> SNIP
> 
>>  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");
> 
> I think the message whouldn't be a warning, the user asked for
> that, maybe something more like:
> 
>   [ perf record: perf size limit reached (XXMB), stopping session ]
> 
>> +		raise(SIGTERM);
> 
> could we just set 'done = 1' what's the benefit in killing perf?

Thanks for your suggestions. Yes, if just set "done == 1" is more efficient and more concise.
And I will modify it and the output format, and then send a v5 patch.
Thanks again.

Regards,
Jiwei

> 
> thanks,
> jirka
> 
>