Re: [PATCH v2] perf record: Add support for limit perf output file size

[Jiwei Sun]

Hi Arnaldo,

On 02/22/2019 10:53 PM, Arnaldo Carvalho de Melo wrote:
> Em Fri, Feb 22, 2019 at 03:19:04PM +0800, Jiwei Sun escreveu:
>> 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.
>>
>> Signed-off-by: Jiwei Sun <jiwei.sun@xxxxxxxxxxxxx>
>> ---
>> v2 changes:
> 
> Please do a v3 adding this new option to
> tools/perf/Documentation/perf-record.txt
> 
> Please also rename it to --max-size-output, because then we coudl use:
> 
> perf record --max-size-output
> 
> or:
> 
> perf record --max-size
> 
> or even:
> 
> perf record --max saving typing :-)
> 
> Also please show it in use, i.e. the output of it working.

Thanks for your advice, I will modify the patch and send a v3.

Thanks,
Regards,
Jiwei

> 
> 
> - Arnaldo
> 
>>   - make patch based on latest Arnaldo's perf/core,
>>   - display warning message when reached the limit.
>> ---
>>  tools/perf/builtin-record.c | 42 +++++++++++++++++++++++++++++++++++++
>>  1 file changed, 42 insertions(+)
>>
>> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
>> index 6c3719ac901d..dc3648c0816d 100644
>> --- a/tools/perf/builtin-record.c
>> +++ b/tools/perf/builtin-record.c
>> @@ -83,6 +83,7 @@ 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;
>> @@ -112,6 +113,12 @@ 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 perf_mmap *map __maybe_unused,
>>  			 void *bf, size_t size)
>>  {
>> @@ -124,6 +131,12 @@ static int record__write(struct record *rec, struct perf_mmap *map __maybe_unuse
>>  
>>  	rec->bytes_written += size;
>>  
>> +	if (record__output_max_size_exceeded(rec)) {
>> +		pr_warning("WARNING: The perf data has already reached "
>> +			   "the limit, stop recording!\n");
>> +		raise(SIGTERM);
>> +	}
>> +
>>  	if (switch_output_size(rec))
>>  		trigger_hit(&switch_output_trigger);
>>  
>> @@ -1671,6 +1684,33 @@ 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)
>> @@ -1982,6 +2022,8 @@ static struct option __record_options[] = {
>>  	OPT_CALLBACK(0, "affinity", &record.opts, "node|cpu",
>>  		     "Set affinity mask of trace reading thread to NUMA node cpu mask or cpu of processed mmap buffer",
>>  		     record__parse_affinity),
>> +	OPT_CALLBACK(0, "output-max-size", &record.output_max_size,
>> +		     "size", "Output file maximum size", parse_output_max_size),
>>  	OPT_END()
>>  };
>>  
>> -- 
>> 2.20.1
>