From: Christoph Hellwig <hch@infradead.org>
To: Dave Chinner <david@fromorbit.com>
Cc: xfs@oss.sgi.com
Subject: Re: [PATCH 1/3] xfs: introduce an allocation workqueue
Date: Mon, 18 Jul 2011 12:00:46 -0400 [thread overview]
Message-ID: <20110718160046.GA14094@infradead.org> (raw)
In-Reply-To: <1310960989-10284-2-git-send-email-david@fromorbit.com>
On Mon, Jul 18, 2011 at 01:49:47PM +1000, Dave Chinner wrote:
> From: Dave Chinner <dchinner@redhat.com>
>
> We currently have significant issues with the amount of stack that
> allocation in XFS uses, especially in the writeback path. We can
> easily consume 4k of stack between mapping the page, manipulating
> the bmap btree and allocating blocks from the free list. Not to
> mention btree block readahead and other functionality that issues IO
> in the allocation path.
>
> As a result, we can no longer fit allocation in the writeback path
> in the stack space provided on x86_64. To alleviate this problem,
> introduce an allocation workqueue and move all allocations to a
> seperate context. This can be easily added as an interposing layer
> into xfs_alloc_vextent(), which takes a single argument structure
> and does not return until the allocation is complete or has failed.
I've mentioned before that I really don't like it, but I suspect there's
not much of an way around it giving the small stacks, and significant
amount of stacks that's already used above and below XFS.
Can we at least have a sysctl nob or mount option to switch back to
direct allocator calls so that we can still debug any performance
or other issues with this one?
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next prev parent reply other threads:[~2011-07-18 16:00 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-07-18 3:49 [PATCH 0/3] xfs: convert more code to use workqueues Dave Chinner
2011-07-18 3:49 ` [PATCH 1/3] xfs: introduce an allocation workqueue Dave Chinner
2011-07-18 16:00 ` Christoph Hellwig [this message]
2011-07-19 1:24 ` Dave Chinner
2011-07-19 2:02 ` Christoph Hellwig
2011-07-19 3:14 ` Dave Chinner
2011-07-18 3:49 ` [PATCH 2/3] xfs: convert xfsbufd to use a workqueue Dave Chinner
2011-07-18 16:01 ` Christoph Hellwig
2011-07-19 1:25 ` Dave Chinner
2011-07-18 3:49 ` [PATCH 3/3] xfs: flush the CIL via " Dave Chinner
2011-07-19 2:03 ` Christoph Hellwig
2011-07-19 3:05 ` Dave Chinner
2011-07-19 3:11 ` Christoph Hellwig
2011-07-19 4:28 ` Dave Chinner
2011-11-30 9:52 ` Christoph Hellwig
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