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 17:28:29 -0800 [thread overview]
Message-ID: <20170201012829.GJ9134@birch.djwong.org> (raw)
In-Reply-To: <20170131191120.GF9134@birch.djwong.org>
On Tue, Jan 31, 2017 at 11:11:20AM -0800, Darrick J. Wong wrote:
> 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.
Reading a little closer, we don't actually change anything in the
on-disk inode, so we can get rid of transaction altogether.
--D
>
> --D
>
> > --
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next prev parent reply other threads:[~2017-02-01 1:30 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
2017-02-01 1:28 ` Darrick J. Wong [this message]
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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