Re: [RFC][Patch 2/2] Persistent preallocation in ext4

[Andreas Dilger <adilger@clusterfs.com>]

On Dec 19, 2006  17:12 +0530, Amit K. Arora wrote:
> I wrote a simple tool to test these patches. The tool takes four
> arguments:
> 
> * command: It may have either of the two values - "prealloc" or "write"
> * filename: This is the filename with relative path
> * offset: The offset within the file from where the preallocation, or
> 		the write should start.
> * length: Total number of bytes to be allocated/written from offset.
> 
> Following cases were tested :
> 1. * preallocation from 0 to 32MB
>    * write to various parts of the preallocated space in sets
>    * observed that the extents get split and also get merged
> 
> 2. * preallocate with holes at various places in the file
>    * write to blocks starting from a hole and ending into preallocated
>       blocks and vice-versa
>    * try to write to entire set of blocks (i.e. from 0 to the last
>       preallocated block) which has holes in between.

An ideal test would be to modify fsx to (randomly) do preallocations
instead of truncates that increase the size.

Cheers, Andreas
--
Andreas Dilger
Principal Software Engineer
Cluster File Systems, Inc.