Re: [PATCH 14/26] mm: back off direct reclaim on excessive shrinker deferral

Dave Chinner
2019-10-11T23:20:38Z

On Fri, Oct 11, 2019 at 09:21:05AM -0700, Matthew Wilcox wrote:
> On Wed, Oct 09, 2019 at 02:21:12PM +1100, Dave Chinner wrote:
> > + if ((reclaim_state->deferred_objects >
> > + sc->nr_scanned - nr_scanned) &&
> > + (reclaim_state->deferred_objects >
> > + reclaim_state->scanned_objects)) {
> > + wait_iff_congested(BLK_RW_ASYNC, HZ/50);
>
> Unfortunately, Jens broke wait_iff_congested() recently, and doesn't plan
> to fix it. We need to come up with another way to estimate congestion.

I know, all the ways the block layer is broken are right there in
the cover letter at the end of the v1 patchset description from
more than 2 months ago.

When people work out how to fix congestion detection and backoff
again, this can be updated at the same time.

Cheers,

Dave.
--
Dave Chinner
david@fromorbit.com