On Fri, Jan 30, 2015 at 10:52 AM, Haomai Wang <haomaiwang@xxxxxxxxx> wrote: >>> As for active write, why do you think it there only one active write >>> in keyvaluestore threads? I just check runtime perf data again, it >>> looks fine that multi write can do concurrently submit transaction. > > You can simply calculate the sum of submit_transaction_sync consuming > time, it would be the multiple of the op thread number. 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). We'll keep experimenting, but we're definitely excited of the possibility of reducing metadata overhead -- 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
