Em Fri, Dec 20, 2013 at 08:57:59AM +0100, Ingo Molnar escreveu:
> * David Ahern <dsah...@gmail.com> wrote:
>
> > Currently perf-stat attempts to show counter stats even if the workload
> > is bogus:
> >
> > $ perf stat -- foo
> > foo: No such file or directory
> >
> > Performance counter stats for 'foo':
> >
> > <not counted> task-clock
> > <not counted> context-switches
> > <not counted> cpu-migrations
> > <not counted> page-faults
> > <not counted> cycles
> > <not counted> stalled-cycles-frontend
> > <not counted> stalled-cycles-backend
> > <not counted> instructions
> > <not counted> branches
> > <not counted> branch-misses
> >
> > 0.009769943 seconds time elapsed
> >
> > It is impossible to differentiate all the failure modes, but it seems
> > reasonable that if the workload handling fails, perf-stat should not try
> > to print stats.
> >
> > With this change:
> >
> > $ perf stat -v -- foo
> > Failed to start workload
> >
> > Signed-off-by: David Ahern <dsah...@gmail.com>
> > Cc: Ingo Molnar <mi...@kernel.org>
> > Cc: Stephane Eranian <eran...@google.com>
>
> Nice!
>
> Acked-by: Ingo Molnar <mi...@kernel.org>
Good intent, but...
[acme@ssdandy linux]$ perf stat usleep 1
Failed to start workload
[acme@ssdandy linux]$
Your patch does:
if (perf_evlist__start_workload(evsel_list) != 0)
But:
int perf_evlist__start_workload(struct perf_evlist *evlist)
{
if (evlist->workload.cork_fd > 0) {
char bf = 0;
int ret;
/*
* Remove the cork, let it rip!
*/
ret = write(evlist->workload.cork_fd, &bf, 1);
if (ret < 0)
perror("enable to write to pipe");
close(evlist->workload.cork_fd);
return ret;
}
return 0;
}
Ret there is 1, so we need to change it to:
return ret != 1 ? -1 : 0;
Right?
- Arnaldo
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