On Tue, Apr 12, 2016 at 10:07:45PM +0800, Songbo Wang wrote: > Hi Dave, > > Thank you for your reply. I did some test today and described those as > follows: > > Delete the existing test file , and redo the test : fio -ioengine=libaio > -bs=4k -direct=1 -thread -rw=randwrite -size=50G -filename=/mnt/test > -name="EBS 4KB randwrite test" -iodepth=64 -runtime=60 > The iops resultes is 19k±(per second); I continue to fio this test file > untill it was filled to the full. Then I did another test using the same > test case, the results was 210k±(per second).(The results mentioned Yup, that's when the workload goes from allocation bound to being an overwrite workload when there is no allocation occurring. Perhaps you should preallocate the file using the fallocate=posix option. This will move the initial overhead to IO completion, so won't block submission, and the file will not end up a fragmented mess as the written areas will merge back into large single extents as more of the file is written. > yesterday was partial. I used the same test file several times, the > results degraded because of the test file was not fill to the full) > > I try to remake the filesystem using the following command to increase the > internal log size , inode size and agcount num: > mkfs.xfs /dev/hioa2 -f -n size=64k -i size=2048,align=1 -d agcount=2045 -l > size=512m > but it has no help to the result. Of course it won't. Turning random knobs without knowing what they do will not solve the problem. Indeed, if you're workload is performance limited because it is running out of log space, then *reducing the log size* will not solve the issue. Users who tweaking knobs without understanding what they do or how they affect the application is the leading cause of filesystem performance and reliability issues on XFS. Just don't do it - all you'll do is cause something to go wrong when you can least afford it to happen. Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
