Messages in this thread | | | From | Alexey Kopytov <> | Subject | Re: Random file I/O regressions in 2.6 [patch+results] | Date | Sat, 22 May 2004 01:13:30 +0400 |
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On Friday 21 May 2004 01:59, Andrew Morton wrote: >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-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
I ran the tests with a configuration as close to yours as possible. Here are the results for mem=256M, 2G total file size (ext3):
2.4.25: Time spent for test: 79.4146s 0.20user 16.08system 3:20.29elapsed 8%CPU Time spent for test: 78.9797s 0.11user 15.84system 3:19.76elapsed 7%CPU
2.6.6-bk, AS: Time spent for test: 81.2208s 0.13user 17.97system 3:13.30elapsed 9%CPU Time spent for test: 82.5538s 0.14user 18.00system 3:14.88elapsed 9%CPU
This correlates very well your results. But when I returned back to my original configuration (mem=640M, 3G total file size), I got the following:
2.4.25: Time spent for test: 77.5377s
2.6.6-bk, AS: Time spent for test: 83.1929s
It seems like the smaller file size just hides the regression, but I have to run some more tests to ensure this.
>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?
It's IDE disk without TCQ support with writeback caching enabled.
-- Alexey Kopytov, Software Developer MySQL AB, www.mysql.com
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