Re: [PATCH v2] mm: vmscan: fix the page state calculation in too_many_isolated

[Vinayak Menon]

On 01/18/2015 01:18 AM, Christoph Lameter wrote:
> On Sat, 17 Jan 2015, Vinayak Menon wrote:
>
> > which had not updated the vmstat_diff. This CPU was in idle for around 30
> > secs. When I looked at the tvec base for this CPU, the timer associated with
> > vmstat_update had its expiry time less than current jiffies. This timer had
> > its deferrable flag set, and was tied to the next non-deferrable timer in the
>
> We can remove the deferrrable flag now since the vmstat threads are only
> activated as necessary with the recent changes. Looks like this could fix
> your issue?

Yes, this should fix my issue.
But I think we may need the fix in too_many_isolated, since there can 
still be a delay of few seconds (HZ by default and even more because of 
reasons pointed out by Michal) which will result in reclaimers 
unnecessarily entering congestion_wait. No ?


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