On Tue, Dec 22, 2015 at 7:18 PM, Don Waterloo <don.waterloo@xxxxxxxxx> wrote: > On 21 December 2015 at 22:07, Yan, Zheng <ukernel@xxxxxxxxx> wrote: >> >> >> > OK, so i changed fio engine to 'sync' for the comparison of a single >> > underlying osd vs the cephfs. >> > >> > the cephfs w/ sync is ~ 115iops / ~500KB/s. >> >> This is normal because you were doing single thread sync IO. If >> round-trip time for each OSD request is about 10ms (network latency), >> you can only have about 100 IOPS. >> >> > > yes... except the RTT is 200us. So that would be 5000 RTT/s. > The time OSD handles request should also be taken into account. please try creating a rbd device, then run "dd if=/dev/zero bs=4k oflag=direct of=/dev/rbdx", the performance number should be roughly the same as cephfs. Regards Yan, Zheng _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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