Re: [UnifiedV4 00/16] The Unified slab allocator (V4)

From: Mel Gorman
Date: Tue Oct 19 2010 - 05:23:57 EST

On Mon, Oct 18, 2010 at 01:13:42PM -0500, Christoph Lameter wrote:
> On Wed, 13 Oct 2010, Mel Gorman wrote:
>
> > Minimally, I see the same sort of hackbench socket performance regression
> > as reported elsewhere (10-15% regression). Otherwise, it isn't particularly
> > exciting results. The machine is very basic - 2 socket, 4 cores, x86-64,
> > 2G RAM. Macine model is an IBM BladeCenter HS20. Processor is Xeon but I'm
> > not sure exact what model. It appears to be from around the P4 times.
>
> Looks not good. Something must still be screwed up. Trouble is to find
> time to do this work. When working on SLAB we had a team to implement the
> NUMA stuff and deal with the performance issues.
>
> > Christoph, in particular while it tests netperf, it is not binding to any
> > particular CPU (although it can), server and client are running on the local
> > machine (which has particular performance characterisitcs of its own) and
> > the tests is STREAM, not RR so the tarball is not a replacement for more
> > targetting testing or workload-specific testing. Still, it should catch
> > some of the common snags before getting into specific workloads without
> > taking an extraordinary amount of time to complete. sysbench might take a
> > long time for many-core machines, limit the number of threads it tests with
> > OLTP_MAX_THREADS in the config file.
>
> That should not matter too much. The performance results should replicate
> SLABs caching behavior and I do not see that in the tests.
>

On the other hand, the unified figures are very close to slab in terms of
behaviour. Very small gains and losses. Considering that the server and
clients are not bound to any particular CPU either and the data set it is
working on is quite large, a small amount of noise is expected.

> > NETPERF UDP
> > netperf-udp netperf-udp udp-slub
> > slab-vanilla slub-vanilla unified-v4r1
> > 64 52.23 ( 0.00%)* 53.80 ( 2.92%) 50.56 (-3.30%) 1.36% 1.00% 1.00%
> > 128 103.70 ( 0.00%) 107.43 ( 3.47%) 101.23 (-2.44%)
> > 256 208.62 ( 0.00%)* 212.15 ( 1.66%) 202.35 (-3.10%) 1.73% 1.00% 1.00%
> > 1024 814.86 ( 0.00%) 827.42 ( 1.52%) 799.13 (-1.97%)
> > 2048 1585.65 ( 0.00%) 1614.76 ( 1.80%) 1563.52 (-1.42%)
> > 3312 2512.44 ( 0.00%) 2556.70 ( 1.73%) 2460.37 (-2.12%)
> > 4096 3016.81 ( 0.00%)* 3058.16 ( 1.35%) 2901.87 (-3.96%) 1.15% 1.00% 1.00%
> > 8192 5384.46 ( 0.00%) 5092.95 (-5.72%) 4912.71 (-9.60%)
> > 16384 8091.96 ( 0.00%)* 8249.26 ( 1.91%) 8004.40 (-1.09%) 1.70% 1.00% 1.00%
>
> Seems that we lost some of the netperf wins.

It's a different test being run here. UDP_STREAM versus UDP_RR and that could
be one factor in the differences between my results and your own. I'll look
into redoing these for *_RR to rule that out as one factor. The results
are outside statistical noise though.

>
> > SYSBENCH
> > sysbench-slab-vanilla-sysbenchsysbench-slub-vanilla-sysbench sysbench-slub
> > slab-vanilla slub-vanilla unified-v4r1
> > 1 7521.24 ( 0.00%) 7719.38 ( 2.57%) 7589.13 ( 0.89%)
> > 2 14872.85 ( 0.00%) 15275.09 ( 2.63%) 15054.08 ( 1.20%)
> > 3 16502.53 ( 0.00%) 16676.53 ( 1.04%) 16465.69 (-0.22%)
> > 4 17831.19 ( 0.00%) 17900.09 ( 0.38%) 17819.03 (-0.07%)
> > 5 18158.40 ( 0.00%) 18432.74 ( 1.49%) 18341.99 ( 1.00%)
> > 6 18673.68 ( 0.00%) 18878.41 ( 1.08%) 18614.92 (-0.32%)
> > 7 17689.75 ( 0.00%) 17871.89 ( 1.02%) 17633.19 (-0.32%)
> > 8 16885.68 ( 0.00%) 16838.37 (-0.28%) 16498.41 (-2.35%)
>
> Same here. Seems that we combined the worst of both.
>

--
Mel Gorman
Part-time Phd Student Linux Technology Center
University of Limerick IBM Dublin Software Lab
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