linux-ext4 - Re: delalloc fragmenting files?

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Message-id: <47291F62.3000008@gmail.com>
Date:	Thu, 01 Nov 2007 03:35:46 +0300
From:	Alex Tomas <bzzz.tomas@...il.com>
To:	Eric Sandeen <sandeen@...hat.com>
Cc:	Andreas Dilger <adilger@....COM>,
	ext4 development <linux-ext4@...r.kernel.org>
Subject: Re: delalloc fragmenting files?

please, try the patch attached.

thanks, Alex

Eric Sandeen wrote:
> One thing that seems to be happening is that thanks to delalloc, a nice
> big request is coming in (only 1036 blocks of the 4096, not quite sure
> why), but then it gets into ext4_mb_normalize_request(), which finds the
> most blocks it can "preallocate" is 256, and chops down the request to
> 256 blocks.  Shouldn't this preallocation be over & above what was asked
> for, vs. reducing the request?
> 
> Ok, so, we get allocations in 256-block chunks...  Why they don't all
> come out contiguous, I don't know yet...
> 
> -Eric


View attachment "mballoc-debug.patch" of type "text/x-patch" (902 bytes)