Re: [PATCH] mm: forbid lumpy-reclaim in shrink_active_list()

[Rik van Riel]

On 03/19/2012 01:58 PM, Konstantin Khlebnikov wrote:
> Rik van Riel wrote:
> > On 03/19/2012 05:18 AM, Konstantin Khlebnikov wrote:
> > > This patch reset reclaim mode in shrink_active_list() to
> > > RECLAIM_MODE_SINGLE | RECLAIM_MODE_ASYNC.
> > > (sync/async sign is used only in shrink_page_list and does not affect
> > > shrink_active_list)
> > >
> > > Currenly shrink_active_list() sometimes works in lumpy-reclaim mode,
> > > if RECLAIM_MODE_LUMPYRECLAIM left over from earlier
> > > shrink_inactive_list().
> > > Meanwhile, in age_active_anon() sc->reclaim_mode is totally zero.
> > > So, current behavior is too complex and confusing, all this looks
> > > like bug.
> > >
> > > In general, shrink_active_list() populate inactive list for next
> > > shrink_inactive_list().
> > > Lumpy shring_inactive_list() isolate pages around choosen one from
> > > both active and
> > > inactive lists. So, there no reasons for lumpy-isolation in
> > > shrink_active_list()
> > >
> > > Proposed-by: Hugh Dickins<hughd@xxxxxxxxxx>
> > > Link: https://lkml.org/lkml/2012/3/15/583
> > > Signed-off-by: Konstantin Khlebnikov<khlebnikov@xxxxxxxxxx>
> >
> > Confirmed, this is already done by commit
> > 26f5f2f1aea7687565f55c20d69f0f91aa644fb8 in the
> > linux-next tree.
>
> No, your patch fix this problem only if CONFIG_COMPACTION=y

True.

It was done that way, because Mel explained to me that deactivating
a whole chunk of active pages at once is a desired feature that makes
it more likely that a whole contiguous chunk of pages will eventually
reach the end of the inactive list.

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