Messages in this thread | | | From | Jeff Moyer <> | Subject | 2.6.30-rc deadline scheduler performance regression for iozone over NFS | Date | Thu, 23 Apr 2009 10:01:58 -0400 |
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Hi,
I've been working on CFQ improvements for interleaved I/Os between processes, and noticed a regression in performance when using the deadline I/O scheduler. The test uses a server configured with a cciss array and 1Gb/s ethernet.
The iozone command line was: iozone -s 2000000 -r 64 -f /mnt/test/testfile -i 1 -w
The numbers in the nfsd's row represent the number of nfsd "threads". These numbers (in MB/s) represent the average of 5 runs.
v2.6.29
nfsd's | 1 | 2 | 4 | 8 --------+---------------+-------+------ deadline| 43207 | 67436 | 96289 | 107590
2.6.30-rc1
nfsd's | 1 | 2 | 4 | 8 --------+---------------+-------+------ deadline| 43732 | 68059 | 76659 | 83231
2.6.30-rc3.block-for-linus
nfsd's | 1 | 2 | 4 | 8 --------+---------------+-------+------ deadline| 46102 | 71151 | 83120 | 82330
Notice the drop for 4 and 8 threads. It may be worth noting that the default number of NFSD threads is 8.
Cheers, Jeff
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