On 8/12/2013 3:43 AM, Wes wrote: > Stan Hoeppner <stan <at> hardwarefreak.com> writes: > > >> ~$ cat /sys/block/sda/queue/scheduler >> [CFQ] noop deadline >> Wes, yours will show CFQ probably as the default on RHEL/CentOS. You'll >> want deadline for best seek and all around performance. So: >> ~$ echo deadline > /sys/block/sda/queue/scheduler >> Add that to an init script or cron entry so it sets on every boot. >> Barriers are not an issue with this test. >> > > Thank you all. The issue is now closed. > RHEL5 was not doing cache flush right. It was only corrected in 2.6.32+ > After removing O_SYNC from seekmark the results are now comparable. Glad you got it figured out. > Actually it is hard to find a linux raw device random R/W benchmark tool and FIO is good for raw IO benchmarking. Can do file based IO as well. Very flexible, but maybe a bit complicated for first time users. > seekmark being the most popular fails when comparing pre and post 2.6.32 > systems (unless you remove O_SYNC). Dunno about seekmark being the most popular. I'd never heard of it until this thread. I'd have guessed FIO was most popular. But then again I don't get out much. ;) -- Stan -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
