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

[Michael Tokarev]

Justin Piszcz wrote:
> 
> On Mon, 1 Mar 2010, Andreas Dilger wrote:
> 
>> On 2010-02-28, at 07:55, Justin Piszcz wrote:
>>> === CREATE RAID-0 WITH 11 DISKS
>>
>> 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.
> 
> Hi,
> 
> 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.
> 
> http://groups.google.com/group/linux.kernel/browse_thread/thread/e7b189bcaa2c1cb4/ad6c2a54b678cf5f?show_docid=ad6c2a54b678cf5f&pli=1
> 
> 
> For the RAID-5 (from earlier testing):  <- This one has 8 disks.

Note that for RAID-5, the "nice" number of disks is 9 as Andreas
said, not 8 as in your example.

/mjt
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