From: Ben Myers <bpm@sgi.com>
To: Brian Foster <bfoster@redhat.com>
Cc: xfs@oss.sgi.com
Subject: Re: [PATCH v2] xfs: increase prealloc size to double that of the previous extent
Date: Thu, 7 Mar 2013 12:45:04 -0600 [thread overview]
Message-ID: <20130307184504.GP22182@sgi.com> (raw)
In-Reply-To: <1361287481-9649-1-git-send-email-bfoster@redhat.com>
On Tue, Feb 19, 2013 at 10:24:41AM -0500, Brian Foster wrote:
> The updated speculative preallocation algorithm for handling sparse
> files can becomes less effective in situations with a high number of
> concurrent, sequential writers. The number of writers and amount of
> available RAM affect the writeback bandwidth slicing algorithm,
> which in turn affects the block allocation pattern of XFS. For
> example, running 32 sequential writers on a system with 32GB RAM,
> preallocs become fixed at a value of around 128MB (instead of
> steadily increasing to the 8GB maximum as sequential writes
> proceed).
>
> Update the speculative prealloc heuristic to base the size of the
> next prealloc on double the size of the preceding extent. This
> preserves the original aggressive speculative preallocation
> behavior and continues to accomodate sparse files at a slight cost
> of increasing the size of preallocated data regions following holes
> of sparse files.
>
> Signed-off-by: Brian Foster <bfoster@redhat.com>
> Reviewed-by: Dave Chinner <dchinner@redhat.com>
Excuse me. This is the version I applied. Not v1.
-Ben
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prev parent reply other threads:[~2013-03-07 18:45 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-19 15:24 [PATCH v2] xfs: increase prealloc size to double that of the previous extent Brian Foster
2013-03-07 18:45 ` Ben Myers [this message]
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