RE: Regression with SLUB on Netperf and Volanomark

[Christoph Lameter <clameter@sgi.com>]

On Fri, 4 May 2007, Tim Chen wrote:

> On Fri, 2007-05-04 at 11:27 -0700, Christoph Lameter wrote:
> 
> > 
> > Not sure where to go here. Increasing the per cpu slab size may hold off 
> > the issue up to a certain cpu cache size. For that we would need to 
> > identify which slabs create the performance issue.
> > 
> > One easy way to check that this is indeed the case: Enable fake NUMA. You 
> > will then have separate queues for each processor since they are on 
> > different "nodes". Create two fake nodes. Run one thread in each node and 
> > see if this fixes it.
> 
> I tried with fake NUMA (boot with numa=fake=2) and use
> 
> numactl --physcpubind=1 --membind=0 ./netserver
> numactl --physcpubind=2 --membind=1 ./netperf -t TCP_STREAM -l 60 -H
> 127.0.0.1 -i 5,5 -I 99,5 -- -s 57344 -S 57344 -m 4096
> 
> to run the tests.  The results are about the same as the non-NUMA case,
> with slab about 5% better than slub.  

Hmmmm... both tests were run in the same context? NUMA has additional 
overhead in other areas.

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