Re: [PATCH] Btrfs: throttle delayed refs better

[Johannes Hirte <johannes.hirte@datenkhaos.de>]

On Wed, 5 Feb 2014 14:36:39 -0500
Josef Bacik <jbacik@fb.com> wrote:

> 
> On 02/05/2014 02:30 PM, Johannes Hirte wrote:
> > On Wed, 5 Feb 2014 14:00:57 -0500
> > Josef Bacik <jbacik@fb.com> wrote:
> >
> >> On 02/05/2014 12:34 PM, Johannes Hirte wrote:
> >>> On Wed, 5 Feb 2014 10:49:15 -0500
> >>> Josef Bacik <jbacik@fb.com> wrote:
> >>>
> >>>> Ok none of those make sense which makes me think it may be the
> >>>> ktime bits, instead of un-applying the whole patch could you just
> >>>> comment out the parts
> >>>>
> >>>>            ktime_t start = ktime_get();
> >>>>
> >>>> and
> >>>>
> >>>>            if (actual_count > 0) {
> >>>>                    u64 runtime =
> >>>> ktime_to_ns(ktime_sub(ktime_get(), start)); u64 avg;
> >>>>
> >>>>                    /*
> >>>>                     * We weigh the current average higher than
> >>>> our current runtime
> >>>>                     * to avoid large swings in the average.
> >>>>                     */
> >>>>                    spin_lock(&delayed_refs->lock);
> >>>>                    avg = fs_info->avg_delayed_ref_runtime * 3 +
> >>>> runtime; avg = div64_u64(avg, 4);
> >>>>                    fs_info->avg_delayed_ref_runtime = avg;
> >>>>                    spin_unlock(&delayed_refs->lock);
> >>>>            }
> >>>>
> >>>> in __btrfs_run_delayed_refs and see if that makes the problem
> >>>> stop? If it does will you try chris's for-linus branch to see if
> >>>> it still reproduces there?  Maybe some patch changed ktime_get()
> >>>> in -rc1 that is causing issues and we're just now exposing it.
> >>>> Thanks,
> >>> With the ktime bits disabled, I wasn't able to reproduce the
> >>> problem anymore. With Chris' for-linus branch it took longer but
> >>> still appeared.
> >>>
> >> Ok can you send your .config, maybe there's some weird time bug
> >> being exposed.  What kind of CPU do you have?  Thanks,
> >>
> >> Josef
> > It's a Core i5-540M, dualcore + hyperthreading
> Ok while I'm doing this can you change 
> btrfs_should_throttle_delayed_refs to _always_ return 1, still with
> all the ktime stuff commented out, and see if that causes the problem
> to happen?  Thanks,

Yes it does. Same behavior as without ktime stuff commented out.