VolanoMark performance improvements (was: Re: volanoMark 12%regression with 2.6.25-rc6)

[Ingo Molnar]

i just tried a handful of kernels with VolanoMark on an Intel quad-core 
testbox, using java-1.6.0-openjdk-1.6.0.0-0.4.b06.fc9.

The result: v2.6.25 is the fastest ever Linux kernel in VolanoMark 
testing, -rc7-to-be is ~41% faster than v2.6.24.2, and ~59% faster than 
v2.6.21, in this Java benchmark:

v2.6.25-rc7-to-be:

  Average throughput = 145613 messages per second
  Average throughput = 142569 messages per second
  Average throughput = 144963 messages per second
  Average throughput = 144998 messages per second
  Average throughput = 144213 messages per second
  Average throughput = 144491 messages per second

v2.6.24.2:

  Average throughput = 101351 messages per second
  Average throughput =  99247 messages per second
  Average throughput = 101155 messages per second
  Average throughput = 103905 messages per second
  Average throughput =  98345 messages per second
  Average throughput = 102775 messages per second

v2.6.21:

  Average throughput =  87630 messages per second
  Average throughput =  91366 messages per second
  Average throughput =  91317 messages per second
  Average throughput =  91317 messages per second
  Average throughput =  91359 messages per second
  Average throughput =  92116 messages per second

these numbers are totally reproducible when running them over a long 
time, i only included 6 runs for brevity. (A sidenote: the 
/proc/sys/kernel/compat_sched_yield switch of 0 or 1 has no effect on 
the .25-rc7 results, and it degraded the .24 results by about 35% so i 
kept it off there.)

so i can see no 12% regression at all - but i have not tried all the 
zillions of older, binary-only Java distributions.

So, to make the tests comparable, and to make some progress on this 
matter, could you please try java-1.6.0-openjdk - what kind of 
VolanoMark numbers do you get with it? If you still see a regression 
with an open Java package too then could you please send me the .config 
of your test-kernel? Thanks,

	Ingo
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