More vm benchmarking

Nick Piggin
2004-02-25T09:11:46Z

Well you can imagine my surprise to see your numbers so I've started
redoing some benchmarks to see what is going wrong.

This first set are 2.6.3, 2.6.3-mm2, 2.6.3-mm3. All SMP kernels
compiled with the same compiler and using the same .config (where
possible). Booting with maxcpus=1 and mem=64M. Test is gcc 3.3.3
compiling 2.4.21. I can provide any other information you're
interested in.

While previously I have been doing a single run of a range of
different parallelisation factors, here I've done two runs each over a
smaller range so you can see I am getting fairly consistient results.

kernel | run | -j5 | -j10 | -j15 |
2.6.3 1 136 886 2511
2.6.3 2 150 838 2465

-mm2 1 136 646 1484
-mm2 2 142 676 1265

-mm3 1 135 881 1828
-mm3 2 146 790 1844

This quite clearly shows your patches hurting as I told you. Why did
it get slower? I assume it is because the batching patch places uneven
pressure on normal and DMA zones. This leads to suboptimal eviction
choice - anything else would be a sign of fundamental problems.

Regarding Nikita and my patches, they all showed improvements on this
machine for this type of test *except* the throttling patch which
didn't cause any change. I just thought it was courteous to try not to
stall a possibly unlucky run.

I will now try a set of SMP tests and possibly ones with different
available memory. I would be disappointed but not very surprised if
SMP is causing lots of problems.