Re: EXT4 is ~2X as slow as XFS (593MB/s vs 304MB/s) for writes?

From: Justin Piszcz
Date: Mon Mar 01 2010 - 04:21:13 EST

On Mon, 1 Mar 2010, Andreas Dilger wrote:

On 2010-02-28, at 07:55, Justin Piszcz wrote:

Have you tried testing with "nice" numbers of disks in your RAID set (e.g. 8 disks for RAID-0, 9 for RAID-5, 10 for RAID-6)? The mballoc code is really much better tuned for power-of-two sized allocations.


Yes, the second system (RAID-5) has 8 disks and it shows the same performance problems with ext4 and not XFS (as shown from previous e-mail), where XFS usually got 500-600MiB/s for writes.

For the RAID-5 (from earlier testing): <- This one has 8 disks.
-o data=writeback,nobarrier: 10737418240 bytes (11 GB) copied, 48.7335 s, 220 MB/s -o data=writeback,nobarrier,nodelalloc: 10737418240 bytes (11 GB) copied, 30.5425 s, 352 MB/s An increase of 132MiB/s.


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