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

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Message-ID: <20061219211409.GP5937@schatzie.adilger.int>
Date:	Tue, 19 Dec 2006 14:14:09 -0700
From:	Andreas Dilger <adilger@...sterfs.com>
To:	"Amit K. Arora" <aarora@...ux.vnet.ibm.com>
Cc:	linux-ext4@...r.kernel.org, suparna@...ibm.com, cmm@...ibm.com,
	suzuki@...ibm.com, alex@...sterfs.com
Subject: Re: [RFC][Patch 2/2] Persistent preallocation in ext4

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.

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