Agreed, I've done a fair amount of testing on this and found that NOOP always performs better with SANs. I always use it for Amazon EBS volumes. On local disks I haven't found much difference between CFQ (RedHat default) and Deadline (Ubuntu default), I imagine this depends on your workload. Most of my tests have focused on MySQL.
You can add "elevator=noop" to your kernel boot options to make it the default. Jonathan On Dec 16, 2010, at 10:48 AM, Ski Kacoroski wrote: > Hi, > > We have a communigate pro email server. For some time now we have had > issues where it was limited to about 800 IOPs and we could not figure > out what was going on. Well it fell off the cliff yesterday and we > tried everything. Today on a whim, I changed the I/O scheduler from > CFQ > to NOOP and bang, the IOPs jumped to 3500 (maxed out our SAN). The > reason I think it made such a big difference is the communigate uses > one > large process with many internal threads instead of several processes. > Anyway, if you are having processes that seem to be I/O bound on > linux, > try changing the I/O scheduler as it may help. It is easy to do: > > To see current scheduler > cat /sys/block/<device>/queue/scheduler > noop anticipatory deadline [cfq] > > To change it: > echo 'NOOP' /sys/block/<device>/queue/scheduler > cat /sys/block/<device>/queue/scheduler > [noop] anticipatory deadline cfq > > cheers, > > ski > > -- > "When we try to pick out anything by itself, we find it > connected to the entire universe" John Muir > > Chris "Ski" Kacoroski, ckacoro...@nsd.org, 206-501-9803 > or ski98033 on most IM services > _______________________________________________ > Tech mailing list > Tech@lists.lopsa.org > https://lists.lopsa.org/cgi-bin/mailman/listinfo/tech > This list provided by the League of Professional System Administrators > http://lopsa.org/ _______________________________________________ Tech mailing list Tech@lists.lopsa.org https://lists.lopsa.org/cgi-bin/mailman/listinfo/tech This list provided by the League of Professional System Administrators http://lopsa.org/
