XFS Preallocate using ALLOCSP

[Eric Sandeen]

Smit Shah wrote:
> On 6/16/09, Felix Blyakher <felixb at sgi.com> wrote:
>> On Jun 16, 2009, at 10:16 AM, Eric Sandeen wrote:


>>> Maybe I should ask what the end goal is here.  :)
>>>
> Just to see if preallocation using fallocate helps reducing the
> fragmentation and increases the throughput.  I guess it wll help
> reduce the fragmentation but the write performance is going to suffer.

Depends on the IO you do, I think.  I'd be curious to know exactly how
you're running preallocation & iometer so I could give it a shot, to see
why xfs seems to be doing worse than ext4.

Thanks,
-Eric