How to reduce IOWAIT?

[sunroof]

Any ideas how to reduce IOWAIT and increase disk speed on my server (CentOS, xeon 2.8 GHz dual, w/4GB of RAM and non-SCSI disks). I get high load average lately...

TOP screenshot: [slibe.com...]

/dev/hda:
Timing buffer-cache reads: 2368 MB in 2.00 seconds = 1184.00 MB/sec
Timing buffered disk reads: 16 MB in 3.20 seconds = 5.00 MB/sec

And what's IRQ and SOFTIRQ?

Thanks!

[jtara]

Your buffered disk reads are awfully slow. The fastest SATA drives should run around 60MB/sec - the fastest SCSI perhaps as high as 80MB/sec. Even if you have ATA drives, you should be doing much better than 5MB/sec.

Something is wrong with your hardware or configuration.

I'm guessing that you are using a default disk driver. Perhaps, say, an ATA driver with a SATA drive. Or accessing the disk through BIOS. Or you are for some reason not using DMA, or not using the highest available DMA mode.