From: "Darrick J. Wong" <darrick.wong@oracle.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: linux-xfs@vger.kernel.org
Subject: Re: [PATCH 7/7] xfs: mark speculative prealloc CoW fork extents unwritten
Date: Tue, 31 Jan 2017 11:11:20 -0800 [thread overview]
Message-ID: <20170131191120.GF9134@birch.djwong.org> (raw)
In-Reply-To: <20170131134135.GA10866@infradead.org>
On Tue, Jan 31, 2017 at 05:41:35AM -0800, Christoph Hellwig wrote:
> Hi Darrick,
>
> from a quick look the code looks reasonable, but I'm worried about
> yet another set of transactions that modify all extents again.
>
> Do you have any measurements of the overhead? I'll see if I
> can prototype my always COW idea to see how the approaches compare.
The overhead should be pretty low -- since the cow fork never goes to
disk, the only thing we end up logging is the inode core (because the
conversion function logs it unconditionally), and I'm not even sure
that's necessary since we're performing a pure conversion of blocks that
are already allocated.
In any case I didn't see any noticeable impact on performance other
than the extra CPU overhead.
--D
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next prev parent reply other threads:[~2017-01-31 19:11 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-31 0:23 [PATCH 0/7] xfs: random fixes Darrick J. Wong
2017-01-31 0:23 ` [PATCH 1/7] xfs: fix toctou race when locking an inode to access the data map Darrick J. Wong
2017-01-31 3:01 ` Eric Sandeen
2017-01-31 13:26 ` Christoph Hellwig
2017-01-31 19:45 ` Darrick J. Wong
2017-01-31 21:40 ` Darrick J. Wong
2017-02-01 2:34 ` [PATCH v2 " Darrick J. Wong
2017-02-01 14:48 ` Christoph Hellwig
2017-01-31 0:23 ` [PATCH 2/7] xfs: fail _dir_open when readahead fails Darrick J. Wong
2017-01-31 4:12 ` Eric Sandeen
2017-01-31 13:29 ` Christoph Hellwig
2017-01-31 0:23 ` [PATCH 3/7] xfs: filter out obviously bad btree pointers Darrick J. Wong
2017-01-31 4:39 ` Eric Sandeen
2017-01-31 20:09 ` Darrick J. Wong
2017-01-31 20:37 ` Eric Sandeen
2017-01-31 0:23 ` [PATCH 4/7] xfs: check for obviously bad level values in the bmbt root Darrick J. Wong
2017-01-31 13:31 ` Christoph Hellwig
2017-01-31 0:23 ` [PATCH 5/7] xfs: verify free block header fields Darrick J. Wong
2017-01-31 13:42 ` Christoph Hellwig
2017-01-31 0:23 ` [PATCH 6/7] xfs: allow unwritten extents in the CoW fork Darrick J. Wong
2017-02-01 2:35 ` [PATCH v2 " Darrick J. Wong
2017-02-01 18:06 ` Christoph Hellwig
2017-01-31 0:23 ` [PATCH 7/7] xfs: mark speculative prealloc CoW fork extents unwritten Darrick J. Wong
2017-01-31 13:41 ` Christoph Hellwig
2017-01-31 19:11 ` Darrick J. Wong [this message]
2017-02-01 1:28 ` Darrick J. Wong
2017-02-01 2:36 ` [PATCH v2 " Darrick J. Wong
2017-02-01 18:36 ` Christoph Hellwig
2017-02-02 15:04 ` Brian Foster
2017-02-02 17:04 ` Darrick J. Wong
2017-02-02 19:42 ` Brian Foster
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