Re: [PATCH v5] perf record: Add support for limit perf output file size

[Jiwei Sun]

Hi Arnaldo,

On 2019e9411f07f% 19:13, Arnaldo Carvalho de Melo wrote:
> Em Fri, Nov 01, 2019 at 09:13:00AM +0100, Jiri Olsa escreveu:
>> On Tue, Oct 22, 2019 at 04:09:01PM +0800, jsun4 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.
>>>  [ perf record: perf size limit reached (10249 KB), stopping session ]
>>>  [ perf record: Woken up 32 times to write data ]
>>>  [ perf record: Captured and wrote 10.133 MB perf.data (71964 samples) ]
>>>
>>>  # ls -lh perf.data
>>>  -rw------- 1 root root 11M Oct 22 14:32 perf.data
>>>
>>>  # ./perf record -a -g --max-size=10K
>>>  [ perf record: perf size limit reached (10 KB), stopping session ]
>>>  Couldn't synthesize bpf events.
>>>  [ perf record: Woken up 0 times to write data ]
>>>  [ perf record: Captured and wrote 1.546 MB perf.data (69 samples) ]
>>>
>>>  # ls -l perf.data
>>>  -rw------- 1 root root 1626952 Oct 22 14:36 perf.data
>>>
>>> Signed-off-by: Jiwei Sun <jiwei.sun@xxxxxxxxxxxxx>
>>> ---
>>> v5 changes:
>>>   - Change the output format like [ perf record: perf size limit XX ]
>>>   - change the killing perf way from "raise(SIGTERM)" to set "done == 1"
>>
>> Acked-by: Jiri Olsa <jolsa@xxxxxxxxxx>
> 
> So, had to add this on top to fix the build on multiple building
> environments, rec->bytes_written is an u64, so we must use PRIu64 or
> else get errors like:
> 
>   builtin-record.c: In function 'record__write':
>   builtin-record.c:150:5: error: format '%lu' expects argument of type 'long unsigned int', but argument 3 has type 'u64' [-Werror=format=]
>        rec->bytes_written >> 10);
>        ^
>     CC       /tmp/build/pe

Sorry for the flaw, and thanks for your suggestion and rectification. 
And I will pay attention to avoid such mistake next time.

Regards,
Jiwei

> 
> 
> - Arnaldo
> 
> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
> index b9ddfcda9611..b95c000c1ed9 100644
> --- a/tools/perf/builtin-record.c
> +++ b/tools/perf/builtin-record.c
> @@ -145,7 +145,7 @@ static int record__write(struct record *rec, struct mmap *map __maybe_unused,
>  	rec->bytes_written += size;
>  
>  	if (record__output_max_size_exceeded(rec) && !done) {
> -		fprintf(stderr, "[ perf record: perf size limit reached (%lu KB),"
> +		fprintf(stderr, "[ perf record: perf size limit reached (%" PRIu64 " KB),"
>  				" stopping session ]\n",
>  				rec->bytes_written >> 10);
>  		done = 1;
>