From: Jesper Dangaard Brouer <brouer@redhat.com>
To: Christoph Lameter <cl@linux.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Pekka Enberg <penberg@kernel.org>,
David Rientjes <rientjes@google.com>,
linux-mm@kvack.org, brouer@redhat.com
Subject: Re: slub: bulk allocation from per cpu partial pages
Date: Fri, 17 Apr 2015 07:44:46 +0200 [thread overview]
Message-ID: <20150417074446.6dd16121@redhat.com> (raw)
In-Reply-To: <alpine.DEB.2.11.1504161049030.8605@gentwo.org>
On Thu, 16 Apr 2015 10:54:07 -0500 (CDT)
Christoph Lameter <cl@linux.com> wrote:
> On Thu, 16 Apr 2015, Jesper Dangaard Brouer wrote:
>
> > On CPU E5-2630 @ 2.30GHz, the cost of kmem_cache_alloc +
> > kmem_cache_free, is a tight loop (most optimal fast-path), cost 22ns.
> > With elem size 256 bytes, where slab chooses to make 32 obj-per-slab.
> >
> > With this patch, testing different bulk sizes, the cost of alloc+free
> > per element is improved for small sizes of bulk (which I guess this the
> > is expected outcome).
> >
> > Have something to compare against, I also ran the bulk sizes through
> > the fallback versions __kmem_cache_alloc_bulk() and
> > __kmem_cache_free_bulk(), e.g. the none optimized versions.
> >
> > size -- optimized -- fallback
> > bulk 8 -- 15ns -- 22ns
> > bulk 16 -- 15ns -- 22ns
>
> Good.
>
> > bulk 30 -- 44ns -- 48ns
> > bulk 32 -- 47ns -- 50ns
> > bulk 64 -- 52ns -- 54ns
>
> Hmm.... We are hittling the atomics I guess... What you got so far is only
> using the per cpu data. Wonder how many partial pages are available
Ups, I can see that this kernel don't have CONFIG_SLUB_CPU_PARTIAL,
I'll re-run tests with this enabled.
--
Best regards,
Jesper Dangaard Brouer
MSc.CS, Sr. Network Kernel Developer at Red Hat
Author of http://www.iptv-analyzer.org
LinkedIn: http://www.linkedin.com/in/brouer
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next prev parent reply other threads:[~2015-04-17 5:47 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-08 18:13 slub bulk alloc: Extract objects from the per cpu slab Christoph Lameter
2015-04-08 22:53 ` Andrew Morton
2015-04-09 14:03 ` Christoph Lameter
2015-04-09 17:16 ` slub: bulk allocation from per cpu partial pages Christoph Lameter
2015-04-16 12:06 ` Jesper Dangaard Brouer
2015-04-16 15:54 ` Christoph Lameter
2015-04-17 5:44 ` Jesper Dangaard Brouer [this message]
2015-04-17 6:06 ` Jesper Dangaard Brouer
2015-04-30 18:40 ` Christoph Lameter
2015-04-30 19:20 ` Jesper Dangaard Brouer
2015-04-09 20:19 ` slub bulk alloc: Extract objects from the per cpu slab Andrew Morton
2015-04-11 2:19 ` Christoph Lameter
2015-04-11 7:25 ` Jesper Dangaard Brouer
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