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Re: [PATCH 2/2] Restore the lowspace extent allocator algorithm

To: Lachlan McIlroy <lachlan@xxxxxxx>
Subject: Re: [PATCH 2/2] Restore the lowspace extent allocator algorithm
From: Dave Chinner <dchinner@xxxxxxxxx>
Date: Mon, 23 Jun 2008 22:00:56 -0700
Cc: xfs-dev <xfs-dev@xxxxxxx>, xfs-oss <xfs@xxxxxxxxxxx>
In-reply-to: <486058F3.3030305@xxxxxxx>
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On Tue, Jun 24, 2008 at 12:16:19PM +1000, Lachlan McIlroy wrote:
> When free space is running low the extent allocator may choose to
> allocate an extent from an AG without leaving sufficient space for
> a btree split when inserting the new extent (see where
> xfs_bmap_btalloc() sets minleft to 0).  In this case the allocator
> will enable the lowspace algorithm which is supposed to allow further
> allocations (such as btree splits and newroots) to allocate from
> sequential AGs.  This algorithm has been broken for a long time
> and this patch restores its behaviour.

Looks ok to me. Perhaps add a comment to the definition of
xbf_low that explains what it is used for so it doesn't
get broken again in future?

Cheers,

Dave.
-- 
Dave Chinner
dchinner@xxxxxxxxx


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