Re: Lockless page cache test results

[Nick Piggin <nickpiggin@yahoo.com.au>]

Chen, Kenneth W wrote:
> Jens Axboe wrote on Wednesday, April 26, 2006 12:46 PM
>
> > > It's interesting, single threaded performance is down a little. Is
> > > this significant? In some other results you showed me with 3 splices
> > > each running on their own file (ie. no tree_lock contention), lockless
> > > looked slightly faster on the same machine.
> >
> > I can do the same numbers on a 2-way em64t for comparison, that should
> > get us a little better coverage.
>
>
>
> I throw the lockless patch and Jens splice-bench into our benchmark harness,
> here are the numbers I collected, on the following hardware:
>
> (1) 2P Intel Xeon, 3.4 GHz/HT, 2M L2
> (2) 4P Intel Xeon, 3.0 GHz/HT, 8M L3
> (3) 4P Intel Xeon, 3.0 GHz/DC/HT, 2M L2 (per core)
>
> Here are the graph:

Thanks a lot Ken.

So pagecache lookup performance goes up about 15-25% in single threaded
tests on your P4s. Phew, I wasn't dreaming it.

It is a pity that ipf hasn't improved similarly (and even slowed down a
bit, if Jens' numbers are significant to that range). Next time I spend
some cycles on lockless pagecache, I'll try to scrounge an ipf and see
if I can't improve it (I don't expect miracles).

Thanks,
Nick

--
SUSE Labs, Novell Inc.
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