On Tue, May 26, 2015 at 4:57 AM, John Spray <john.spray@xxxxxxxxxx> wrote: > > > On 26/05/2015 07:55, Yan, Zheng wrote: >> >> the reason for slow file creations is that bonnie++ call fsync(2) after >> each creat(2). fsync() wait for safe replies of the create requests. MDS >> sends safe reply when log event for the request gets journaled safely. MDS >> flush the journal every 5 seconds (mds_tick_interval). So the speed of file >> creation for bonnie++ is one file every file seconds. > > > Ah, I hadn't noticed that the benchmark called... I wonder if I'm seeing the > fuse client return quickly because it simply doesn't implement the fsyncdir > call. We should fix that! > > It looks like we used to have an OP_FSYNC in the client-server protocol > (perhaps for flushing the log immediately on fsyncs), anyone have any > background on why that went away? Following up, we discussed this in standup and the answer was "no". Seeing the question in context of this thread, though, I think maybe I've asked before and either the answer or the deduced reason was "because we didn't want to let clients force an (expensive) MDS log flush". -Greg -- 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
