Messages in this thread | | | From | Sergey Meirovich <> | Date | Wed, 8 Jan 2014 16:43:07 +0200 | Subject | Re: Terrible performance of sequential O_DIRECT 4k writes in SAN environment. ~3 times slower then Solars 10 with the same HBA/Storage. |
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Hi Christoph,
On 8 January 2014 16:03, Christoph Hellwig <hch@infradead.org> wrote: > On Tue, Jan 07, 2014 at 08:37:23PM +0200, Sergey Meirovich wrote: >> Actually my initial report (14.67Mb/sec 3755.41 Requests/sec) was about ext4 >> However I have tried XFS as well. It was a bit slower than ext4 on all >> occasions. > > I wasn't trying to say XFS fixes your problem, but that we could > implement appending AIO writes in XFS fairly easily. > > To verify Jan's theory, can you try to preallocate the file to the full > size and then run the benchmark by doing a: > > # fallocate -l <size> <filename> > > and then run it? If that's indeed the issue I'd be happy to implement > the "real aio" append support for you as well. >
After fallocate: [root@illin01 ext4]# du -k test_file.* | awk '{print $1}' |sort |uniq 81920 [root@illin01 ext4]# fallocate -l 81920k test_file.*
Results are almost the same: 14.68Mb/sec 3758.02 Requests/sec
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