Messages in this thread | | | Date | Thu, 20 May 2004 14:59:02 -0700 | From | Andrew Morton <> | Subject | Re: Random file I/O regressions in 2.6 [patch+results] |
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(Resend due to osdl<->vger smtp bunfight)
Alexey Kopytov <alexeyk@mysql.com> wrote: > > Ram Pai wrote: > > >Attached the cleaned up patch and the performance results of the patch. > > > >Overall Observation: > > 1.Small improvement with iozone with the patch, and overall > > much better performance than 2.4 > > 2.Small/neglegible improvement with DSS workload. > > 3.Negligible impact with sysbench, but results worser than > > 2.4 kernels > > Ram, can you clarify the status of this patch please?
Everything we have is now in Linus's tree. And in 2.6.6-mm4.
> I ran the same sysbench test on my hardware with patched 2.6.6 and got > 122.2348s execution time, i.e. almost the same results as in the original > tests. Is this patch an intermediate step to improve the sysbench workload on > 2.6, or it just addresses another problem?
The patches in Linus's tree improve sysbench significantly here. It's a 256MB 2-way with IDE disks, writeback caching enabled:
sysbench --num-threads=16 --test=fileio --file-total-size=2G --file-test-mode=rndrw run
2.4.27-pre2, ext2:
Time spent for test: 61.0240s 0.06s user 6.03s system 4% cpu 2:05.95 total Time spent for test: 60.8456s 0.11s user 5.49s system 4% cpu 2:04.94 total
2.6.6, CFQ, ext2:
Time spent for test: 85.6614s 0.05s user 5.66s system 3% cpu 2:26.75 total Time spent for test: 85.2090s 0.06s user 5.32s system 3% cpu 2:24.75 total
2.6.6-bk, CFQ, ext2:
Time spent for test: 66.7717s 0.04s user 5.54s system 4% cpu 2:06.19 total Time spent for test: 67.5666s 0.04s user 5.10s system 4% cpu 2:06.72 total
2.6.6, as, ext2:
Time spent for test: 83.8358s 0.07s user 5.89s system 4% cpu 2:22.92 total Time spent for test: 83.8068s 0.06s user 5.34s system 3% cpu 2:21.33 total
2.6.6-bk, AS, ext2:
Time spent for test: 62.5316s 0.05s user 5.27s system 4% cpu 2:01.28 total Time spent for test: 62.7401s 0.04s user 5.17s system 4% cpu 2:00.50 total
2.6.6, deadline, ext2:
Time spent for test: 103.0084s 0.06s user 5.76s system 3% cpu 2:40.74 total Time spent for test: 101.9648s 0.07s user 5.35s system 3% cpu 2:38.83 total
2.6.6-bk, deadline, ext2:
Time spent for test: 63.3405s 0.03s user 5.49s system 4% cpu 2:01.05 total Time spent for test: 63.5288s 0.03s user 5.05s system 4% cpu 2:00.78 total
There's still something wrong here. 2.6.6-bk+deadline is pretty equivalent to 2.4 from an IO scheduler point of view in this test. Yet it's a couple of percent slower.
I don't know why you're still seeing significant discrepancies.
What sort of disk+controller system are you using? If scsi, what is the tag queue depth set to? Is writeback caching enabled on the disk?
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