newer MPT speed issue on Linux

From: Roger Heflin
Date: Tue Jul 18 2006 - 13:28:33 EST


I am have tested with Sles9.1sp1, Sp3, and and
here are some results:

SLES9.1sp1 (kernel only) 100-120MB/second writes 75-80MB/second reads
SLES9.0sp3 20-30MB/second writes 20-30MB/second writes 140-150MB/second reads

This is with the LSI Logic / Symbios Logic FC929X Fibre Channel Adapter (rev 81)

All 3 are with a SLES9sp3 distribution and are on the same machine with only the kernel
being changed. The test is a simple "dd if=/dev/zero of=/dev/dk001/two bs=65536 &"
with vmstat being used to determine io speed. Bonnie++ is getting similar results
to what dd is generating when writing to a filesystem.

The fiber channel card is hooked to a external raid5 chassis, and it being accessed
though LVM.

Are there some parameters that I am missing that could speed the writes up?

The reads on the newer driver are a nice improvement, but the writes on
the newer driver are horrible in my testing.

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