From: Joonsoo Kim <iamjoonsoo.kim@lge.com>
To: Christoph Lameter <cl@linux.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Pekka Enberg <penberg@kernel.org>,
David Rientjes <rientjes@google.com>,
Jesper Dangaard Brouer <brouer@redhat.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 06/11] mm/slab: don't keep free slabs if free_objects exceeds free_limit
Date: Wed, 30 Mar 2016 17:25:14 +0900 [thread overview]
Message-ID: <20160330082514.GE1678@js1304-P5Q-DELUXE> (raw)
In-Reply-To: <alpine.DEB.2.20.1603282000270.31323@east.gentwo.org>
On Mon, Mar 28, 2016 at 08:03:16PM -0500, Christoph Lameter wrote:
> On Mon, 28 Mar 2016, js1304@gmail.com wrote:
>
> > From: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> >
> > Currently, determination to free a slab is done whenever free object is
> > put into the slab. This has a problem that free slabs are not freed
> > even if we have free slabs and have more free_objects than free_limit
>
> There needs to be a better explanation here since I do not get why there
> is an issue with checking after free if a slab is actually free.
Okay. Consider following 3 objects free situation.
free_limt = 10
nr_free = 9
free(free slab) free(free slab) free(not free slab)
If we check it one by one, when nr_free > free_limit (at last free),
we cannot free the slab because current slab isn't a free slab.
But, if we check it lastly, we can free 1 free slab.
I will add more explanation on the next version.
>
> > when processed slab isn't a free slab. This would cause to keep
> > too much memory in the slab subsystem. This patch try to fix it
> > by checking number of free object after all free work is done. If there
> > is free slab at that time, we can free it so we keep free slab as minimal
> > as possible.
>
> Ok if we check after free work is done then the number of free slabs may
> be higher than the limit set and then we free the additional slabs to get
> down to the limit that was set?
Yes.
Thanks.
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next prev parent reply other threads:[~2016-03-30 8:23 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-28 5:26 mm/slab: reduce lock contention in alloc path js1304
2016-03-28 5:26 ` [PATCH 01/11] mm/slab: hold a slab_mutex when calling __kmem_cache_shrink() js1304
2016-03-29 0:50 ` Christoph Lameter
2016-03-30 8:11 ` Joonsoo Kim
2016-03-31 10:53 ` Nikolay Borisov
2016-04-01 2:18 ` Joonsoo Kim
2016-03-28 5:26 ` [PATCH 02/11] mm/slab: remove BAD_ALIEN_MAGIC again js1304
2016-03-28 8:58 ` Geert Uytterhoeven
2016-03-30 8:11 ` Joonsoo Kim
2016-03-28 21:19 ` Andrew Morton
2016-03-29 0:53 ` Christoph Lameter
2016-03-28 5:26 ` [PATCH 03/11] mm/slab: drain the free slab as much as possible js1304
2016-03-29 0:54 ` Christoph Lameter
2016-03-28 5:26 ` [PATCH 04/11] mm/slab: factor out kmem_cache_node initialization code js1304
2016-03-29 0:56 ` Christoph Lameter
2016-03-30 8:12 ` Joonsoo Kim
2016-03-28 5:26 ` [PATCH 05/11] mm/slab: clean-up kmem_cache_node setup js1304
2016-03-29 0:58 ` Christoph Lameter
2016-03-30 8:15 ` Joonsoo Kim
2016-03-28 5:26 ` [PATCH 06/11] mm/slab: don't keep free slabs if free_objects exceeds free_limit js1304
2016-03-29 1:03 ` Christoph Lameter
2016-03-30 8:25 ` Joonsoo Kim [this message]
2016-03-28 5:26 ` [PATCH 07/11] mm/slab: racy access/modify the slab color js1304
2016-03-29 1:05 ` Christoph Lameter
2016-03-30 8:25 ` Joonsoo Kim
2016-03-28 5:26 ` [PATCH 08/11] mm/slab: make cache_grow() handle the page allocated on arbitrary node js1304
2016-03-28 5:26 ` [PATCH 09/11] mm/slab: separate cache_grow() to two parts js1304
2016-03-28 5:27 ` [PATCH 10/11] mm/slab: refill cpu cache through a new slab without holding a node lock js1304
2016-03-28 5:27 ` [PATCH 11/11] mm/slab: lockless decision to grow cache js1304
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