On 05/26/2015 06:57 AM, John Spray 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!
I seem to remember someone grumbling about this a while back but I don't
really remember the details or who it was. :)
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?
Cheers,
John
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