From: Christoph Lameter <cl@linux.com>
To: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Pekka Enberg <penberg@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
David Rientjes <rientjes@google.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [REPOST PATCH 3/4] slab: introduce byte sized index for the freelist of a slab
Date: Mon, 9 Sep 2013 14:44:03 +0000 [thread overview]
Message-ID: <00000141032dea11-c5aa9c77-b2f2-4cab-b7a0-d37665a6cec8-000000@email.amazonses.com> (raw)
In-Reply-To: <20130909043217.GB22390@lge.com>
On Mon, 9 Sep 2013, Joonsoo Kim wrote:
> 32 byte is not minimum object size, minimum *kmalloc* object size
> in default configuration. There are some slabs that their object size is
> less than 32 byte. If we have a 8 byte sized kmem_cache, it has 512 objects
> in 4K page.
As far as I can recall only SLUB supports 8 byte objects. SLABs mininum
has always been 32 bytes.
> Moreover, we can configure slab_max_order in boot time so that we can't know
> how many object are in a certain slab in compile time. Therefore we can't
> decide the size of the index in compile time.
You can ignore the slab_max_order if necessary.
> I think that byte and short int sized index support would be enough, but
> it should be determined at runtime.
On x86 f.e. it would add useless branching. The branches are never taken.
You only need these if you do bad things to the system like requiring
large contiguous allocs.
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next prev parent reply other threads:[~2013-09-09 14:44 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-06 5:57 [REPOST PATCH 0/4] slab: implement byte sized indexes " Joonsoo Kim
2013-09-06 5:57 ` [REPOST PATCH 1/4] slab: factor out calculate nr objects in cache_estimate Joonsoo Kim
2013-09-06 15:48 ` Christoph Lameter
2013-09-09 4:32 ` Joonsoo Kim
2013-09-06 5:57 ` [REPOST PATCH 2/4] slab: introduce helper functions to get/set free object Joonsoo Kim
2013-09-06 15:49 ` Christoph Lameter
2013-09-06 5:57 ` [REPOST PATCH 3/4] slab: introduce byte sized index for the freelist of a slab Joonsoo Kim
2013-09-06 15:58 ` Christoph Lameter
2013-09-09 4:32 ` Joonsoo Kim
2013-09-09 14:44 ` Christoph Lameter [this message]
2013-09-10 5:43 ` Joonsoo Kim
2013-09-10 21:25 ` Christoph Lameter
2013-09-11 1:04 ` Joonsoo Kim
2013-09-11 14:22 ` Christoph Lameter
2013-09-12 6:52 ` Joonsoo Kim
2013-09-06 5:57 ` [REPOST PATCH 4/4] slab: make more slab management structure off the slab Joonsoo Kim
2013-09-06 15:59 ` Christoph Lameter
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