On Oct 1, 2010, at 11:01 AM, Eric Shubert wrote:

> Alex Dean wrote:
>> On Oct 1, 2010, at 3:32 AM, der.hans wrote:
>>> Am 30. Sep, 2010 schwätzte Eric Shubert so:
>>> 
>>>> Which elevator is being used?
>>>> (cat /sys/block/sda/queue/scheduler)
>>> noop anticipatory deadline [cfq]
>>> 
>>>> Using async i/o? Synchronous writes are very slow.
>>> Hmm, not familiar with libaio. Looks like we have it installed.
>>> 
>>>> I presume ext3, since you referred to noatime. If you have directories with many files (e.g. Maildir), dir_index option can help.
>>> Yeah, ext3. Mostly it's a few DB files and some log files. No mail
>>> directories.
>> FWIW: A few years ago, I recall seeing somewhat-improved benchmark performance from MySQL after switching to the deadline scheduler.
> 
> I'd give that a shot - can't hurt to try.
> # echo deadline >/sys/block/sda/queue/scheduler

I thought it required a reboot to change scheduler.  Maybe that's changed in more recent kernels.  (This was RHEL4, so 2.6.9-something.)

alex
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