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Subject: Re: [patch] SLQB slab allocator (try 2)
From: "Zhang, Yanmin" <yanmin_zhang@linux.intel.com>
To: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Mel Gorman <mel@csn.ul.ie>, Nick Piggin <nickpiggin@yahoo.com.au>,
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Date: Tue, 17 Feb 2009 09:06:55 +0800
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On Mon, 2009-02-16 at 21:17 +0200, Pekka Enberg wrote:
> Hi Mel,
> 
> Mel Gorman wrote:
> > I haven't done much digging in here yet. Between the large page bug and
> > other patches in my inbox, I haven't had the chance yet but that doesn't
> > stop anyone else taking a look.
> 
> So how big does an improvement/regression have to be not to be 
> considered within noise? I mean, I randomly picked one of the results 
> ("x86-64 speccpu integer tests") and ran it through my "summarize" 
> script and got the following results:
> 
> 		min      max      mean     std_dev
>    slub		0.96     1.09     1.01     0.04
>    slub-min	0.95     1.10     1.00     0.04
>    slub-rvrt	0.90     1.08     0.99     0.05
>    slqb		0.96     1.07     1.00     0.04
> 
> Apart from slub-rvrt (which seems to be regressing, interesting) all the 
> allocators seem to perform equally well. Hmm?
I wonder if different compilation of kernel might cause different cache alignment
which has much impact on small result difference.

If a workload isn't slab-allocation intensive, perhaps the impact caused by different
compilation is a little bigger.


> 
> Btw, Yanmin, do you have access to the tests Mel is running (especially 
> the ones where slub-rvrt seems to do worse)?
As it takes a long time (more than 20 hours) to run cpu2006, I run cpu2000 instead
of cpu2006. Now, we are trying to integrate cpu2006 into testing infrastructure.
Let me check it firstly.

>  Can you see this kind of 
> regression? The results make we wonder whether we should avoid reverting 
> all of the page allocator pass-through and just add a kmalloc cache for 
> 8K allocations. Or not address the netperf regression at all. Double-hmm.
> 
> 			Pekka