Write speeds have decreased 10% to 30% between 2.6.18.1 and 2.6.19.1.
Read speeds are unchanged at 1.15 GB/Sec.

Using a SuperMicro H8DC8 or Tyan 2895 or a Tyan 2915 (Socket F)
with 4 2.2GHz Opterons, 16GB RAM, dual LSI 8408E SAS controllers
into 4 X 4 Raid0s. XFS file system. The only difference is the Kernel Rev.
16 Seagate 7200.10 Sata drives, with 3.AAE firmware (very important!).
LSI 8408E firmware rev is 1.02.01-0158. Adapter readahead is disabled.
(Enabling readahead with this firmware costs 25% in write performance :-( )

Under 2.6.18.1, I/O peaks at 256.1 MB/Sec into each raid0 - 1GB/Sec.
The average is 230 MB/Sec over the first TB. With 2.6.19.1,
the peak is 220 MB/Sec, and the average is 170 MB/Sec.

EXT3 runs 2-3X slower than XFS for this benchmark, so it is hard
to see where the regression appeared. I'm not really too worried
about it, but that much of a decrease is worth reporting.
Since there were significant XFS changes between the revs,
it might not be worthwhile for me to chase the exact update
that causes this issue.

berkley


 
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//E. F. Berkley Shands, MSc//

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