From: Christoph Hellwig <hch@lst.de>
To: Brian Foster <bfoster@redhat.com>
Cc: darrick.wong@oracle.com, xfs@oss.sgi.com
Subject: Re: stop using ioends for direct write completions
Date: Tue, 2 Feb 2016 17:42:37 +0100 [thread overview]
Message-ID: <20160202164237.GA25436@lst.de> (raw)
In-Reply-To: <20160202153117.GB1853@bfoster.bfoster>
On Tue, Feb 02, 2016 at 10:31:18AM -0500, Brian Foster wrote:
> FWIW, I don't see any such review comments against the three versions of
> the "DIO needs an ioend for writes" patch I have in my mailbox, but I
> easily could have missed something..? But if there wasn't time, then
> fair enough.
I'll have to look at the mailboxes, but I remember Dave sending this
out and complaining.
> I'm just looking for context. I don't have much of an opinion on which
> approach is used here. If it simplifies COW, then that seems good enough
> reason to me to take this approach. I'm pointing this out more because
> this code seems to have been rewritten the last couple of times we
> needed to fix something, which makes backports particularly annoying.
> The two patches above were associated with a broader enhancement and a
> bug fix (respectively) as a sort of justification, whereas this post had
> a much more vague purpose from what I could tell, and therefore why I at
> least hadn't taken the time to review it.
>
> If COW is the primary motivator, perhaps we can bundle it with that
> work?
The prime motivator is to:
(1) avoid a pointless memory allocation
(2) avoid a pointless context switch
(3) avoid pointless code complexity
COW is just another case where these show up.
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next prev parent reply other threads:[~2016-02-02 16:42 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-14 10:10 stop using ioends for direct write completions Christoph Hellwig
2016-01-14 10:10 ` [PATCH] xfs: don't use " Christoph Hellwig
2016-01-28 13:16 ` stop using " Christoph Hellwig
2016-01-28 20:53 ` Darrick J. Wong
2016-01-28 21:10 ` Christoph Hellwig
2016-01-28 21:58 ` Darrick J. Wong
2016-01-28 22:02 ` Christoph Hellwig
2016-01-28 22:31 ` Darrick J. Wong
2016-01-29 8:01 ` Christoph Hellwig
2016-01-29 14:12 ` Brian Foster
2016-02-01 21:54 ` Darrick J. Wong
2016-02-02 11:17 ` Christoph Hellwig
2016-02-02 15:26 ` Brian Foster
2016-02-02 11:20 ` Christoph Hellwig
2016-02-02 15:31 ` Brian Foster
2016-02-02 16:42 ` Christoph Hellwig [this message]
2016-02-03 22:22 ` Dave Chinner
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