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From: Mel Gorman <mgorman@techsingularity.net>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	linux-api@vger.kernel.org, Roman Gushchin <guro@fb.com>,
	Michal Hocko <mhocko@kernel.org>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Christoph Lameter <cl@linux.com>,
	David Rientjes <rientjes@google.com>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Matthew Wilcox <willy@infradead.org>
Subject: Re: [PATCH v3 3/7] mm, slab: allocate off-slab freelists as reclaimable when appropriate
Date: Thu, 19 Jul 2018 09:35:30 +0100	[thread overview]
Message-ID: <20180719083530.jhugqzkvjnbrddim@techsingularity.net> (raw)
In-Reply-To: <20180718133620.6205-4-vbabka@suse.cz>

On Wed, Jul 18, 2018 at 03:36:16PM +0200, Vlastimil Babka wrote:
> In SLAB, OFF_SLAB caches allocate management structures (currently just the
> freelist) from kmalloc caches when placement in a slab page together with
> objects would lead to suboptimal memory usage. For SLAB_RECLAIM_ACCOUNT caches,
> we can allocate the freelists from the newly introduced reclaimable kmalloc
> caches, because shrinking the OFF_SLAB cache will in general result to freeing
> of the freelists as well. This should improve accounting and anti-fragmentation
> a bit.
> 
> Signed-off-by: Vlastimil Babka <vbabka@suse.cz>

I'm not quite convinced by this one. The freelist cache is tied to the
lifetime of the slab and not the objects. A single freelist can be reclaimed
eventually but for caches with many objects per slab, it could take a lot
of shrinking random objects to reclaim one freelist. Functionally the
patch appears to be fine.

-- 
Mel Gorman
SUSE Labs

  reply	other threads:[~2018-07-19  8:35 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-07-18 13:36 [PATCH v3 0/7] kmalloc-reclaimable caches Vlastimil Babka
2018-07-18 13:36 ` [PATCH v3 1/7] mm, slab: combine kmalloc_caches and kmalloc_dma_caches Vlastimil Babka
2018-07-19  8:10   ` Mel Gorman
2018-07-20  9:30     ` Vlastimil Babka
2018-07-30 15:38   ` Christopher Lameter
2018-07-18 13:36 ` [PATCH v3 2/7] mm, slab/slub: introduce kmalloc-reclaimable caches Vlastimil Babka
2018-07-19  8:23   ` Mel Gorman
2018-07-20  9:32     ` Vlastimil Babka
2018-07-19 18:16   ` Roman Gushchin
2018-07-19 18:16     ` Roman Gushchin
2018-07-20  9:35     ` Vlastimil Babka
2018-07-30 15:41   ` Christopher Lameter
2018-07-18 13:36 ` [PATCH v3 3/7] mm, slab: allocate off-slab freelists as reclaimable when appropriate Vlastimil Babka
2018-07-19  8:35   ` Mel Gorman [this message]
2018-07-20  9:37     ` Vlastimil Babka
2018-07-30 15:45   ` Christopher Lameter
2018-07-18 13:36 ` [PATCH v3 4/7] dcache: allocate external names from reclaimable kmalloc caches Vlastimil Babka
2018-07-19  8:42   ` Mel Gorman
2018-07-18 13:36 ` [PATCH v3 5/7] mm: rename and change semantics of nr_indirectly_reclaimable_bytes Vlastimil Babka
2018-07-30 15:46   ` Christopher Lameter
2018-07-18 13:36 ` [PATCH v3 6/7] mm, proc: add KReclaimable to /proc/meminfo Vlastimil Babka
2018-07-18 13:36 ` [PATCH v3 7/7] mm, slab: shorten kmalloc cache names for large sizes Vlastimil Babka
2018-07-19  8:46   ` Mel Gorman
2018-07-30 15:48   ` Christopher Lameter
2018-07-31  8:55     ` Vlastimil Babka
2018-07-19 19:53 ` [PATCH v3 0/7] kmalloc-reclaimable caches Roman Gushchin
2018-07-19 19:53   ` Roman Gushchin
2018-07-20  9:45   ` Vlastimil Babka

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