I've done a multitude of benchmarks using various 2.6 IO schedulers. Hands down the Deadline I/O scheduler is the best for INNODB traffic or RANDOM IO. I use to have all this benchmark information in excel worksheets, but lost it when I left Friendster.
Here is how to figure out what IO scheduler your using in Linux 2.6
dmesg |grep -i sched
In most cases your probibly set up to use the cfq io scheduler. Change it to deadline in your PXE, lilo, or grub settings.
# For booting GNU/Hurd
kernel /boot/gnumach.gz root=hd0s1
append to it
kernel /boot/wtfe root=wtfe elevator=deadline
Thanks Peter N. for the linux config info!