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Wed, 6 Jan 2021 09:49:38 +0000 (UTC) Received: from krava (unknown [10.40.194.249]) by smtp.corp.redhat.com (Postfix) with SMTP id 2347771CA1; Wed, 6 Jan 2021 09:49:34 +0000 (UTC) Date: Wed, 6 Jan 2021 10:49:34 +0100 From: Jiri Olsa To: Stephane Eranian Cc: Jiri Olsa , Arnaldo Carvalho de Melo , lkml , Peter Zijlstra , Ingo Molnar , Mark Rutland , Namhyung Kim , Alexander Shishkin , Michael Petlan , Ian Rogers , Alexei Budankov Subject: Re: [PATCHv2] perf tools: Detect when pipe is passed as perf data Message-ID: <20210106094934.GA972880@krava> References: <20201230110935.582332-1-jolsa@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jan 05, 2021 at 05:33:38PM -0800, Stephane Eranian wrote: > Hi, > > On Wed, Dec 30, 2020 at 3:09 AM Jiri Olsa wrote: > > > > Currently we allow pipe input/output only through '-' string > > being passed to '-o' or '-i' options, like: > > > It seems to me it would be useful to auto-detect that the perf.data > file is in pipe vs. file mode format. > Your patch detects the type of the file which is something different > from the format of its content. hi, it goes together with the format, once the output file is pipe, the format is pipe as well jirka > Thanks. > > > # mkfifo perf.pipe > > # perf record --no-buffering -e 'sched:sched_switch' -o - > perf.pipe & > > [1] 354406 > > # cat perf.pipe | ./perf --no-pager script -i - | head -3 > > perf 354406 [000] 168190.164921: sched:sched_switch: perf:354406.. > > migration/0 12 [000] 168190.164928: sched:sched_switch: migration/0:.. > > perf 354406 [001] 168190.164981: sched:sched_switch: perf:354406.. > > ... > > > > This patch detects if given path is pipe and set the perf data > > object accordingly, so it's possible now to do above with: > > > > # mkfifo perf.pipe > > # perf record --no-buffering -e 'sched:sched_switch' -o perf.pipe & > > [1] 360188 > > # perf --no-pager script -i ./perf.pipe | head -3 > > perf 354442 [000] 168275.464895: sched:sched_switch: perf:354442.. > > migration/0 12 [000] 168275.464902: sched:sched_switch: migration/0:.. > > perf 354442 [001] 168275.464953: sched:sched_switch: perf:354442.. > > > > It's of course possible to combine any of above ways. > > > > Signed-off-by: Jiri Olsa > > --- > > v2: > > - removed O_CREAT|O_TRUNC flags from pipe's write end > > > > tools/perf/util/data.c | 27 +++++++++++++++++++++------ > > 1 file changed, 21 insertions(+), 6 deletions(-) > > > > diff --git a/tools/perf/util/data.c b/tools/perf/util/data.c > > index f29af4fc3d09..4dfa9e0f2fec 100644 > > --- a/tools/perf/util/data.c > > +++ b/tools/perf/util/data.c > > @@ -159,7 +159,7 @@ int perf_data__update_dir(struct perf_data *data) > > return 0; > > } > > > > -static bool check_pipe(struct perf_data *data) > > +static int check_pipe(struct perf_data *data) > > { > > struct stat st; > > bool is_pipe = false; > > @@ -172,6 +172,15 @@ static bool check_pipe(struct perf_data *data) > > } else { > > if (!strcmp(data->path, "-")) > > is_pipe = true; > > + else if (!stat(data->path, &st) && S_ISFIFO(st.st_mode)) { > > + int flags = perf_data__is_read(data) ? > > + O_RDONLY : O_WRONLY; > > + > > + fd = open(data->path, flags); > > + if (fd < 0) > > + return -EINVAL; > > + is_pipe = true; > > + } > > } > > > > if (is_pipe) { > > @@ -190,7 +199,8 @@ static bool check_pipe(struct perf_data *data) > > } > > } > > > > - return data->is_pipe = is_pipe; > > + data->is_pipe = is_pipe; > > + return 0; > > } > > > > static int check_backup(struct perf_data *data) > > @@ -344,8 +354,11 @@ static int open_dir(struct perf_data *data) > > > > int perf_data__open(struct perf_data *data) > > { > > - if (check_pipe(data)) > > - return 0; > > + int err; > > + > > + err = check_pipe(data); > > + if (err || data->is_pipe) > > + return err; > > > > /* currently it allows stdio for pipe only */ > > data->use_stdio = false; > > @@ -410,8 +423,10 @@ int perf_data__switch(struct perf_data *data, > > { > > int ret; > > > > - if (check_pipe(data)) > > - return -EINVAL; > > + ret = check_pipe(data); > > + if (ret || data->is_pipe) > > + return ret; > > + > > if (perf_data__is_read(data)) > > return -EINVAL; > > > > -- > > 2.26.2 > > >