From: Vlastimil Babka <vbabka@suse.cz>
To: Mel Gorman <mgorman@techsingularity.net>
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: Fri, 20 Jul 2018 11:37:34 +0200 [thread overview]
Message-ID: <d164e040-3422-96c7-68e2-7efdf8818874@suse.cz> (raw)
In-Reply-To: <20180719083530.jhugqzkvjnbrddim@techsingularity.net>
On 07/19/2018 10:35 AM, Mel Gorman wrote:
> 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.
Hm you're right that the reclaimability of freelist is maybe too much
detached, and could do more harm than good for the reclaimable caches. I
will probably drop it unless I can measure it's an improvement. Thanks.
next prev parent reply other threads:[~2018-07-20 9:40 UTC|newest]
Thread overview: 26+ 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
2018-07-20 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
2018-07-20 9:37 ` Vlastimil Babka [this message]
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
2018-07-20 9:45 ` Vlastimil Babka
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