linux-kernel - Re: [PATCH v2 0/5] introduce kcompactd and stop compacting in kswapd

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Message-ID: <20160309155238.GK27018@dhcp22.suse.cz>
Date:	Wed, 9 Mar 2016 16:52:38 +0100
From:	Michal Hocko <mhocko@...nel.org>
To:	Vlastimil Babka <vbabka@...e.cz>
Cc:	linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org,
	Andrea Arcangeli <aarcange@...hat.com>,
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
	Rik van Riel <riel@...hat.com>,
	Joonsoo Kim <iamjoonsoo.kim@....com>,
	Mel Gorman <mgorman@...hsingularity.net>,
	David Rientjes <rientjes@...gle.com>,
	Johannes Weiner <hannes@...xchg.org>
Subject: Re: [PATCH v2 0/5] introduce kcompactd and stop compacting in kswapd

On Mon 08-02-16 14:38:06, Vlastimil Babka wrote:
> The previous RFC is here [1]. It didn't have a cover letter, so the description
> and results are in the individual patches.

FWIW I think this is a step in the right direction. I would give my
Acked-by to all patches but I wasn't able to find time for a deep review
and my lack of knowledge of compaction details doesn't help much. I do
agree that conflating kswapd with compaction didn't really work out well
and fixing this would just make the code more complex and would more
prone to new bugs. In future we might want to invent something similar
to watermarks and set an expected level of high order pages prepared for
the allocation (e.g. have at least XMB of memory in order-9+). kcompact
then could try as hard as possible to provide them. Does that sound at
least doable?

Thanks!
-- 
Michal Hocko
SUSE Labs