On Fri, Dec 17, 2021 at 08:51:01AM -0800, Andrii Nakryiko wrote:
> On Fri, Dec 17, 2021 at 6:11 AM Paul Chaignon <paul@xxxxxxxxxxxxx> wrote:
> >
> > The output of bpftool prog tracelog is currently buffered, which is
> > inconvenient when piping the output into other commands. A simple
> > tracelog | grep will typically not display anything. This patch fixes it
> > by flushing the tracelog output after each line from the trace_pipe file.
> >
> > Fixes: 30da46b5dc3a ("tools: bpftool: add a command to dump the trace pipe")
> > Signed-off-by: Quentin Monnet <quentin@xxxxxxxxxxxxx>
> > Signed-off-by: Paul Chaignon <paul@xxxxxxxxxxxxx>
> > ---
> > Changes in v2:
> > - Resending to fix a format error.
> >
> > tools/bpf/bpftool/tracelog.c | 1 +
> > 1 file changed, 1 insertion(+)
> >
> > diff --git a/tools/bpf/bpftool/tracelog.c b/tools/bpf/bpftool/tracelog.c
> > index e80a5c79b38f..b310229abb07 100644
> > --- a/tools/bpf/bpftool/tracelog.c
> > +++ b/tools/bpf/bpftool/tracelog.c
> > @@ -158,6 +158,7 @@ int do_tracelog(int argc, char **argv)
> > jsonw_string(json_wtr, buff);
> > else
> > printf("%s", buff);
> > + fflush(stdout);
>
> maybe it's better to
>
> setlinebuf(stdout);
>
> for the entire bpftool instead?
Makes sense. I've sent a v3 at
https://lore.kernel.org/bpf/20211220214528.GA11706@Mem/T/.
>
>
> > }
> >
> > fclose(trace_pipe_fd);
> > --
> > 2.25.1
> >
