On 2026-03-08 13:18, Jan Hubicka wrote:
On 2026-03-08 10:28, Jan Hubicka wrote:
> > From: Dhruv Chawla <[email protected]>
> >
> > This is a partial fix for PR124075 which forces perf record to write
> > the
> > profile out to perf.data. This is required because I noticed on both
> > aarch64 and x86 that it was writing out the profile to stdout at
> > times,
> > which would cause profile information to be dropped. This did not fail
> > in the various create_fdas_for_* targets because they would only try
> > and
> > access the perf profiles if they existed at their paths.
> >
> > Further work for this patch is to plumb the PERF_DATA make variable
> > into
> > the perf record invocation, but that is a stage 1 thing.
> >
> > Autoprofilebootstrapped and regtested on aarch64-linux-gnu.
> >
> > Signed-off-by: Dhruv Chawla <[email protected]>
> >
> > gcc/ChangeLog:
> > PR gcov-profile/124075
> > * config/aarch64/gcc-auto-profile: Add "-o perf.data" to perf
> > record invocation.
> > * config/i386/gcc-auto-profile: Likewise.
>
> I have similar change in my tree for some time, so i can do
> profiledbootstraps without getting perf data accidentlly streamed into
> redirected stdout/stderr. I do it in the Makefile.ac instead of
> perf.data.
>
> Again I would like Andy to have chance to comment, but the change looks
> OK to me.
I don't think I've ever seen that issue. You get the perf.data binary
blob in the output? It shouldn't have anything to do with redirection
or
not.
-o perf.data is default.
For me
perf record ls 2>&1 | tee out
outputs the perf data to out. This also happens with
make autoprofiledboostrap 2>&1 | tee out
and always surprises me
Ah I see it in the perf source. If the output file is a pipe it believes
it's in pipe mode
(for perf inject)
util/data.c:check_pipe()
if (!data->path) {
if (!fstat(fd, &st) && S_ISFIFO(st.st_mode))
is_pipe = true;
} else {
if (!strcmp(data->path, "-"))
is_pipe = true;
}
Okay the patch makes sense then.
Thanks,
-Andi
