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?
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