On 02/10/2015 12:55 PM, Stefan Priebe wrote:
Hello, last year in june i already reported this but there was no real result. (http://lists.ceph.com/pipermail/ceph-users-ceph.com/2014-July/041070.html) I then had the hope that this will be fixed itself when hammer is released. Now i tried hammer an the results are bad as before. Since firefly librbd1 / librados2 are 20% slower for 4k random iop/s than dumpling - this is also the reason why i still stick to dumpling. I've now modified my test again to be a bit more clear. Ceph cluster itself completely dumpling. librbd1 / librados from dumpling (fio inside qemu): 23k iop/s for random 4k writes - stopped qemu - cp -ra firefly_0.80.8/usr/lib/librados.so.2.0.0 /usr/lib/ - cp -ra firefly_0.80.8/usr/lib/librbd.so.1.0.0 /usr/lib/ - start qemu same fio, same qemu, same vm, same host, same ceph dumpling storage, different librados / librbd: 16k iop/s for random 4k writes What's wrong with librbd / librados2 since firefly?
Hi Stephen, Just off the top of my head, some questions to investigate: What happens to single op latencies? Does enabling/disabling RBD cache have any effect? How's CPU usage? (Does perf report show anything useful?) Can you get trace data? Mark
Greets, Stefan -- 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
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