On 04/06/2015 02:54, Lionel Bouton wrote: >> I have never tested these parameters (osd_disk_thread_ioprio_priority and >> osd_disk_thread_ioprio_class), but did you check that the I/O scheduler of >> the disks is cfq? > > Yes I did.
Ah ok. It was just in case. :) >> Because, if I understand well, these parameters have no >> effect if the I/O scheduler is no cfq > > AFAIK cfq is the only elevator supporting priorities in the mainline kernel. Ok. >> By the way, even if I don't use these parameters, should I use cfq I/O >> scheduler instead of deadline? Is there a best I/O scheduler for Ceph? > > It probably depends on your actual workload. It may depend on your > hardware too: some benchmarks have shown it to perform faster on HDD but > slower than deadline or noop on SSD. Interesting... I have only HDD (no SSD) and currently the I/O scheduler is "deadline" (the default scheduler of my Ubuntu Trusty). So, I'll think about switching from "deadline" to "cfq"... Thanks for your answer Lionel. ;) -- François Lafont _______________________________________________ ceph-users mailing list [email protected] http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
