Re: [PATCH 2/3] tools/power turbostat: avoid an infinite loop of restarts

[David Arcari]

I see.  Perhaps this isn't fixable then.  I'll take another look.

-DA

On 11/25/25 2:12 PM, Len Brown wrote:
> this patch introduces a limit of 10-restarts per turbostat lifetime,
> down from infinity.
>
> some turbostat invocations span multiple uses of cpu online/offline --
> so this limit will not fly.
>
> On Tue, Nov 18, 2025 at 10:58 AM David Arcari <darcari@xxxxxxxxxx> wrote:
> > There are some error cases where turbostat will attempt to reinitialize
> > by calling the re_initialize() function.  The code attempts to avoid
> > an infinite loop by checking the value of 'restarted' in one case, but
> > not others. It should be checked in all cases of restart.  Additonally,
> > the 'restarted' is reset to zero at the start of the loop which also
> > needs to be removed.
> >
> > Signed-off-by: David Arcari <darcari@xxxxxxxxxx>
> > Cc: Len Brown <lenb@xxxxxxxxxx>
> > Cc: linux-kernel@xxxxxxxxxxxxxxx
> > ---
> >   tools/power/x86/turbostat/turbostat.c | 10 +++++-----
> >   1 file changed, 5 insertions(+), 5 deletions(-)
> >
> > diff --git a/tools/power/x86/turbostat/turbostat.c b/tools/power/x86/turbostat/turbostat.c
> > index 584b0f7f9067..5567b9ecd516 100644
> > --- a/tools/power/x86/turbostat/turbostat.c
> > +++ b/tools/power/x86/turbostat/turbostat.c
> > @@ -6722,7 +6722,11 @@ void turbostat_loop()
> >          set_my_sched_priority(-20);
> >
> >   restart:
> > -       restarted++;
> > +       if (restarted++ > 10) {
> > +               if (!retval)
> > +                       retval = -1;
> > +               exit(retval);
> > +       }
> >
> >          snapshot_proc_sysfs_files();
> >          retval = for_all_cpus(get_counters, EVEN_COUNTERS);
> > @@ -6730,13 +6734,9 @@ void turbostat_loop()
> >          if (retval < -1) {
> >                  exit(retval);
> >          } else if (retval == -1) {
> > -               if (restarted > 10) {
> > -                       exit(retval);
> > -               }
> >                  re_initialize();
> >                  goto restart;
> >          }
> > -       restarted = 0;
> >          done_iters = 0;
> >          gettimeofday(&tv_even, (struct timezone *)NULL);
> >
> > --
> > 2.51.0