On Tue, 2 Sep 2008 10:21:31 -0700 MHR <mhullrich@xxxxxxxxx> wrote: > On Tue, Sep 2, 2008 at 9:51 AM, Joseph L. Casale > <JCasale@xxxxxxxxxxxxxxxxx> wrote: > > > > Appreciate that info, I have just been reading about the difference but > > cant say I understand in real life what the difference between deadline > > versus cfq is. I will try changing it on the fly and running my tests. > > > > The CFQ elevator algorithm attempts to be fair to all i/o requests, > without specific regard to performance. The deadline elevator is more > aggressive in scheduling for minimal latency per device. > > For example, if you have one process that is doing more or less random > i/o and another that is doing large block sequential i/o, the deadline > elevator will pander to the latter whereas the cfq elevator will try > to be fair in scheduling the i/os between the processes. > > Here's a decent, short write up on them: > http://www.redhat.com/magazine/008jun05/features/schedulers/ > > HTH > > mhr > _______________________________________________ > CentOS mailing list > CentOS@xxxxxxxxxx > http://lists.centos.org/mailman/listinfo/centos ionice? has nobidy mentioned this? -- Martyn Hare <martyn.hare@xxxxxxxxx>
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