Re: [PATCH -mm] vmscan: move reclaim_state handling to shrink_slab

From: Vladimir Davydov
Date: Thu Jan 15 2015 - 02:56:28 EST


On Wed, Jan 14, 2015 at 03:34:49PM -0800, Andrew Morton wrote:
> On Wed, 14 Jan 2015 16:55:36 +0300 Vladimir Davydov <vdavydov@xxxxxxxxxxxxx> wrote:
> > This patch also makes shrink_slab() return the number of reclaimed slab
> > pages (obtained from reclaim_state) instead of the number of reclaimed
> > objects, because the latter is not of much use - it was only checked by
> > drop_slab() to decide whether it should continue reclaim or abort. The
> > number of reclaimed pages is more appropriate, because it also can be
> > used by shrink_zone() to accumulate scan_control->nr_reclaimed.
>
> Not sure that this is a good change. If shrink_slab() managed to free
> some objects but didn't free any pages then that's a good sign that
> additional calls to shrink_slab() *will* free some pages. With this
> change, drop_slab_node() can give up too early.

Fair enough. We'd better leave the return value intact then. I think we
should add an additional argument to add the number of reclaimed slab
pages to, as I intended to do initially. Will resend.

Thanks,
Vladimir
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