Re: [PATCH 3/8] mm/vmscan: Throttle reclaim when no progress is being made

[Mel Gorman]

On Wed, Nov 24, 2021 at 11:43:05AM +0100, Vlastimil Babka wrote:
> >> Any thoughts?  For now I can just hack around this by skipping
> >> reclaim_throttle if cgroup_reclaim() == true, but that's probably not
> >> the correct fix. :)
> >> 
> > 
> > No, it wouldn't be but a possibility is throttling for only 1 jiffy if
> > reclaiming within a memcg and the zone is balanced overall.
> > 
> > The interruptible part should just be the patch below. I need to poke at
> > the cgroup limit part a bit
> 
> As the throttle timeout is short anyway, will the TASK_UNINTERRUPTIBLE vs
> TASK_INTERRUPTIBLE make a difference for the (ability to kill? AFAIU
> typically this inability to kill is because of a loop that doesn't check for
> fatal_signal_pending().
> 

Yep, and the fatal_signal_pending() is lacking within reclaim in general
but I'm undecided on how much that should change in the context of reclaim
throttling but at minimum, I don't want the signal delivery to be masked
or delayed.

-- 
Mel Gorman
SUSE Labs