On Thu, Feb 21, 2019 at 02:44:19PM +0800, 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.
> 
> Signed-off-by: Jiwei Sun <jiwei....@windriver.com>
> ---
>  tools/perf/builtin-record.c | 39 +++++++++++++++++++++++++++++++++++++
>  1 file changed, 39 insertions(+)
> 
> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
> index 882285fb9f64..28a03929166d 100644
> --- a/tools/perf/builtin-record.c
> +++ b/tools/perf/builtin-record.c
> @@ -81,6 +81,7 @@ struct record {
>       bool                    timestamp_boundary;
>       struct switch_output    switch_output;
>       unsigned long long      samples;
> +     unsigned long           output_max_size;        /* = 0: unlimited */

please rebase to latest Arnaldo's perf/core,
there are new fields in here now

>  };
>  
>  static volatile int auxtrace_record__snapshot_started;
> @@ -106,6 +107,12 @@ 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)
>  {
> @@ -118,6 +125,9 @@ static int record__write(struct record *rec, struct 
> perf_mmap *map __maybe_unuse
>  
>       rec->bytes_written += size;
>  
> +     if (record__output_max_size_exceeded(rec))
> +             raise(SIGTERM);

perhaps display some message saying we reached the limit

other than that looks good to me

thanks,
jirka


> +
>       if (switch_output_size(rec))
>               trigger_hit(&switch_output_trigger);
>  
> @@ -1639,6 +1649,33 @@ static int parse_clockid(const struct option *opt, 
> const char *str, int unset)
>       return -1;
>  }
>  
> +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)
> @@ -1946,6 +1983,8 @@ static struct option __record_options[] = {
>                    &nr_cblocks_default, "n", "Use <n> control blocks in 
> asynchronous trace writing mode (default: 1, max: 4)",
>                    record__aio_parse),
>  #endif
> +     OPT_CALLBACK(0, "output-max-size", &record.output_max_size,
> +                  "size", "Output file maximum size", parse_output_max_size),
>       OPT_END()
>  };
>  
> -- 
> 2.20.1
> 

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