> On Fri, Oct 10, 2014 at 7:44 AM, dboyzhong <dboyzh...@163.com > <mailto:dboyzh...@163.com>> wrote: > > Hi. when i put a object(1K) to swift cluster, the performance is so > bad, QPS only 16. and i found the function: "_finalize_put" in file > Diskfile.py cost too much time . mainly caused by the fsync() inside > _finalize_put operation, the fsync() will cost 30ms when write 1KB > data to disk . as a result the PUT performance is bad.
Using a single thread, multiple, threads, spinning disks, SSDs? This highly depends on your configuration. And 30ms for a single fsync() is a lot of time, is the disk used heavily? Or is this the actual time for the whole HTTP request? > how can tuning the performance ? and why call fsync() function? The fsync() call ensures that all data is written to disk before the clients gets a response, stating that everything is ok. Doing this (and doing this on at least the quorum of the configured replicas) a client can be sure that the data is actually stored multiple times on disk. Otherwise there might be a failure before the data gets written to the disk, and in a worst case scenario that data is lost. Christian _______________________________________________ Mailing list: http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack Post to : openstack@lists.openstack.org Unsubscribe : http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack
