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5.x filesystem performance regression
Having fixed my performace-critical RAID configuration, I think there's some
serious filesystem performance regression from 4.x to 5.x.
I've tested every possible combination of 4.0.1 vs. 5.1, softdep vs. WAPBL,
parity maps enabled vs. disabled, bare disc vs. RAID 1 vs. RAID 5.
The test case was extracting the 5.1 src.tgz set onto the filesystem under test.
The extraction was done twice (having deleted the extracted tree in between);
in some cases the time for the first run is missing because I forgot to time
the tar command.
All tests are on identical hardware, a 4G amd64 system with three Seagate
ST336607LW discs on an Adaptec 19160 SCSI controller.
In the following table, the two figures in each column are elapsed seconds
for the two runs.
plain disc RAID 1 RAID 5 16k RAID 5 32k
4.0.1 softdep 64s 12s ? 11s ? 17s 54s 12s
5.1 softdep 51s 42s 65s 60s 330s 347s 218s 250s
5.1 log 66s 30s 84s 25s ? 426s 194s 190s
5.1 softdep, no parity map 63s 61s 339s 331s not measured
5.1 log, no parity map 88s 26s ? 340s not measured
Both RAIDs have 32 sectPerSU.
The filesystem on the RAID 1 has a 16k bsize, on RAID 5, I tested both 16k/32k.
So, almost everywhere, 4.0.1 is three to fiveteen times as fast as 5.1.
Any ideas where to look further? Anyone to confirm my measurements?
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