I am already using deadline scheduler, with the default parameters: read_expire=500 write_expire=5000 writes_starved=2 front_merges=1 fifo_batch=16
I remember tuning them before, didn't make a great difference. -Simon On Fri, Oct 31, 2014 at 3:43 PM, Nick Fisk <n...@fisk.me.uk> wrote: > Hi Simon, > > > > Have you tried using the Deadline scheduler on the Linux nodes? The > deadline scheduler prioritises reads over writes. I believe it tries to > service all reads within 500ms whilst writes can be delayed up to 5s. > > > > I don’t the exact effect Ceph will have over the top of this, but this > would be the first thing I would try. > > > > Nick > > > > *From:* ceph-users [mailto:ceph-users-boun...@lists.ceph.com] *On Behalf > Of *Xu (Simon) Chen > *Sent:* 31 October 2014 19:37 > *To:* ceph-users@lists.ceph.com > *Subject:* [ceph-users] prioritizing reads over writes > > > > Hi all, > > > > My workload is mostly writes, but when the writes reach a certain > throughput (iops wise not much higher) the read throughput would tank. This > seems to be impacting my VMs' responsiveness overall. Reads would recover > after write throughput drops. > > > > Is there any way to prioritize read over write, or at least guarantee a > certain level of aggregated read throughput in a cluster? > > > > Thanks. > > -Simon > >
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