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

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Date:   Thu, 7 Nov 2019 08:13:56 -0300
From:   Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>
To:     Jiri Olsa <jolsa@...hat.com>
Cc:     jsun4 <jiwei.sun@...driver.com>, 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,
        jiwei.sun.bj@...com
Subject: Re: [PATCH v5] perf record: Add support for limit perf output file
 size

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@...driver.com>
> > ---
> > 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@...nel.org>

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


- 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;