[CentOS] Control IO related to a process
martyn.hare at gmx.co.uk
Tue Sep 2 19:11:57 UTC 2008
On Tue, 2 Sep 2008 10:21:31 -0700
MHR <mhullrich at gmail.com> wrote:
> On Tue, Sep 2, 2008 at 9:51 AM, Joseph L. Casale
> <JCasale at activenetwerx.com> 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:
> CentOS mailing list
> CentOS at centos.org
ionice? has nobidy mentioned this?
Martyn Hare <martyn.hare at gmx.co.uk>
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