Re: [PATCH 1/5] vmscan: remove all_unreclaimable check from directreclaim path completely

From: Andrew Morton
Date: Wed Mar 23 2011 - 23:09:32 EST


On Thu, 24 Mar 2011 11:48:19 +0900 (JST) KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> wrote:

> > On Thu, 24 Mar 2011 11:11:46 +0900 (JST) KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> wrote:
> >
> > > Subject: [PATCH] vmscan: remove all_unreclaimable check from direct reclaim path completely
> >
> > zone.all_unreclaimable is there to prevent reclaim from wasting CPU
> > cycles scanning a zone which has no reclaimable pages. When originally
> > implemented it did this very well.
> >
> > That you guys keep breaking it, or don't feel like improving it is not a
> > reason to remove it!
> >
> > If the code is unneeded and the kernel now reliably solves this problem
> > by other means then this should have been fully explained in the
> > changelog, but it was not even mentioned.
>
> The changelog says, the logic was removed at 2008. three years ago.
> even though it's unintentionally. and I and minchan tried to resurrect
> the broken logic and resurrected a bug in the logic too. then, we
> are discussed it should die or alive.
>
> Which part is hard to understand for you?
>

The part which isn't there: how does the kernel now address the problem
which that code fixed?

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