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

[Arnaldo Carvalho de Melo]

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.


- 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

-- 

- Arnaldo