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Date: Sat, 11 Apr 2015 09:25:43 +0200
From: Jesper Dangaard Brouer <brouer@redhat.com>
Subject: Re: slub bulk alloc: Extract objects from the per cpu slab
Message-ID: <20150411092543.6c1b395d@redhat.com>
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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


On Fri, 10 Apr 2015 21:19:06 -0500 (CDT) Christoph Lameter <cl@linux.com> wrote:
> On Thu, 9 Apr 2015, Andrew Morton wrote:
> 
[...]
> > Keeping them in -next is not a problem - I was wondering about when to
> > start moving the code into mainline.
> 
> When Mr. Brouer has confirmed that the stuff actually does some good for
> his issue.

I plan to pickup working on this from Monday. (As Christoph already
knows, I've just moved back to Denmark from New Zealand.)

I'll start with micro benchmarking, to make sure bulk-alloc is faster
than normal-alloc.  Once we/I have some framework, we can easier
compare the different optimizations that Christoph is planning.

The interesting step for me is using this in the networking stack.

For real use-cases, like IP-forwarding, my experience tells me that the
added code size can easily reduce the performance gain, because
of more instruction-cache misses.  Fortunately bulk-alloc is call
less-times, which amortize these icache-misses, but still something we
need to be aware of as it will not show-up in micro benchmarking.

ps. Thanks for the work guys! :-)
-- 
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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