The below observations (including high CPU usage by the OSDs) hold true when we (roughly) double the performance of the MySQL backend by pointing it to SSDs instead of rotary media. This causes us to suspect that our current bottleneck is not the extra load placed on the backend by the metadata; but rather something in the OSD which causes it to be unable to saturate the backend. Any thoughts? On Tue, Feb 3, 2015 at 10:13 AM, Chris Pacejo <cpacejo@xxxxxxxxxxxxxxxx> wrote: > I've instrumented submit_transaction to tick up/down an atomic > counter. While in certain situations (resource-constrained VM; OSD > startup), I do see up to "keyvaluestore op threads" number of > concurrent transaction submits reported by this counter, on real > hardware, during `rados bench` with 2700-byte objects, I never see > more than 3 concurrent submits; on average, I see 2. I don't know the > OSD's internals well enough to speculate on the cause, but it's worth > noting that the OSD processes consume a lot of CPU (170%+) during > these benchmarks (compared to 14% for 1 MiB objects). -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
