I noticed that changing vfs.read_max from the default 8 to 16 has a dramatic effect on sequential read performance. Increasing it further did not have measurable effect.
Increasing MAXPHYS in sys/param.h from 128k to 1M increased sequential read thruput on my MegaRAID 1600 from 100MB/s to 190MB/s measured on 5.4
#RAID0 7*36GB MegaRAID 1600 MAXPHYS=1M t125# dd if=/dev/amrd0 of=/dev/null bs=1024k count=1024 1073741824 bytes transferred in 5.559722 secs (193128691 bytes/sec)
It had no effect on bonnie so the filesystem probaby never issues block-reads that large, I'll try the above sysctl.
190MB/s is pretty good considering that the card is in a ServerWorks LE chipped P3 and that the internal datapath on the Elite 1600 is only 64-bit/33MHz.
/Martin
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