| Date | Thu, 17 Jan 2002 15:13:56 +0100 | From | Andrea Arcangeli <> | Subject | blkdev speedup |
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On Wed, Jan 16, 2002 at 11:44:37PM +0100, Chris Chabot wrote: > > > Test hardware: > > 4 way Dell, 4 GB physical RAM, SCSI/RAID subsystem, > > DB runs on FS. > > Can we first make sure that the other factors dont plat a rol in this > benchmark? I have a couple (14+) Dell servers here, and i know for a > fact that most of their RAID systems are heavely borked in the > performance department. > > All kernels upto 2.4.1x performed horibly, and all kernels after 2.4.16 > or so perform horibly again! Somewhere inbetween some magic seemed to > happen in the block layer / elevator code / etc, that caused performance > to increase upto 100% on the Dell PERC adapters. (started @ the first > release of the AA VM). However after a few small releases, the
if you're using the blkdev directly, then please try to mount the blkdev with a 4k filesystem before making your benchmark, that should give you the magic performance back. 2.4.10 intentionally were defaulting to 4k I/O, this is probably what made the difference for you.
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