Re: MySQL not using optimum disk throughput.

[Greg Whalin]

What drives are you using?  For SCSI RAID, you definitly want deadline 
scheduler.  That said, even after the switch to deadline, we saw our 
Opteron's running way slow (compared to older slower Xeons).  Whatever 
the problem is, we fought it for quite a while (though difficult to test 
too much w/ production dbs) and ended up rolling back to 2.4.

Kevin Burton wrote:
Kevin Burton wrote:
Greg Whalin wrote:
Deadline was much faster.  Using sysbench:
test:
sysbench --num-threads=16 --test=fileio --file-total-size=20G 
--file-test-mode=rndrw run


So... FYI.  I rebooted with elevator=deadline as a kernel param.
db2:~# cat /sys/block/sda/queue/scheduler
noop anticipatory [deadline] cfq
(which I assume means I'm now running deadline.  Is there any other way 
to find out?)

And no performance diff.  Note that you're benchmarks only show a 20M 
addition overhead.  We're about 60x too slow for these drives so I'm not 
sure what could be going on here :-/

Kevin

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