RE: Regression with SLUB on Netperf and Volanomark

[Tim Chen <tim.c.chen@linux.intel.com>]

On Mon, 2007-05-07 at 18:49 -0700, Christoph Lameter wrote:
> On Mon, 7 May 2007, Tim Chen wrote:
> 
> > However, the output from TCP_STREAM is quite stable.  
> > I am still seeing a 4% difference between the SLAB and SLUB kernel.
> > Looking at the L2 cache miss rate with emon, I saw 6% more cache miss on
> > the client side with SLUB.  The server side has the same amount of cache
> > miss.  This is test under SMP mode with client and server bound to
> > different core on separate package.
> 
> Could you try the following patch on top of 2.6.21-mm1 with the patches
> from http://ftp.kernel.org/pub/linux/kernel/people/christoph/slub-patches?
> 
> I sent it to you before. This is one is an updated version
> 
> 
> 
> Avoid atomic overhead in slab_alloc and slab_free
> 

I tried the slub-patches and the avoid atomic overhead patch against
2.6.21-mm1.  It brings the TCP_STREAM performance for SLUB to the SLAB
level.  The patches not mentioned in the "series" file did not apply
cleanly to 2.6.21-mm1 and I skipped most of those.  

Patches applied are: 
http://ftp.kernel.org/pub/linux/kernel/people/christoph/slub-
patches/series + dentry_target_reclaimed + kmem_cache_ops + slub_stats +
skip_atomic_overhead

Without skip atomic overhead patch, the throughput drops by 1 to 1.5%.

The change from slub_min_order=0 slub_max_order=4 
to slub_min_order=6 slub_max_order=7 did not make much difference in
my tests.


Tim

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