Le 10/01/2014 17:16, Bradley Kite a écrit :
This might explain why the performance is not so good - on each
connection it can only do 1 transaction at a time:
1) Submit write
2) wait...
3) Receive ACK
Then repeat...
But if the OSD protocol supports multiple transactions it could do
something like this:
1) Submit 1
2) Submit 2
3) Submit 3
4) Recv ACK 1
5) Submit 4
6) Recv ACK 2
What you are describing here are sync and async writes, from what I
understand those behaviours are defined by initial write calls flags
(posix O_SYNC or O_ASYNC), and ideally have to be honoured all the way
to the final storage back-end (the drives) to ensure data consistency
(if something goes wrong). For exemple : fio => iSCSI => CEPH => drives
What options did you pass to your benchmark tool ?
--
Cédric
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