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From: Matthew Wilcox <willy@linux.intel.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Matthew Wilcox <matthew.r.wilcox@intel.com>,
	linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
	linux-kernel@vger.kernel.org, Hugh Dickins <hughd@google.com>
Subject: Re: [PATCH v3 5/7] swap: Use bdev_read_page() / bdev_write_page()
Date: Thu, 24 Apr 2014 14:57:40 -0400	[thread overview]
Message-ID: <20140424185740.GE5886@linux.intel.com> (raw)
In-Reply-To: <20140424111817.9cc62b2ff1e368c5cf27d262@linux-foundation.org>

On Thu, Apr 24, 2014 at 11:18:17AM -0700, Andrew Morton wrote:
> On Sun, 13 Apr 2014 18:59:54 -0400 Matthew Wilcox <matthew.r.wilcox@intel.com> wrote:
> 
> >  mm/page_io.c | 23 +++++++++++++++++++++--
> >  1 file changed, 21 insertions(+), 2 deletions(-)
> 
> Some changelog here would be nice.  What were the reasons for the
> change?  Any observable performance changes?

Whoops ... I could swear I wrote one.  Wonder what happened to it.  Here
was all I had:

We can avoid allocating a BIO if we use the writepage path instead of
the Direct I/O path.

But that's kind of lame.  I don't have any performance numbers right now,
so how about we go with:

By calling the device driver to write the page directly, we avoid
allocating a BIO, which allows us to free memory without allocating
memory.

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  reply	other threads:[~2014-04-24 18:57 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-04-13 22:59 [PATCH v3 0/7] Page I/O Matthew Wilcox
2014-04-13 22:59 ` [PATCH v3 1/7] Remove block_write_full_page_endio() Matthew Wilcox
2014-04-13 22:59 ` [PATCH v3 2/7] Factor clean_buffers() out of __mpage_writepage() Matthew Wilcox
2014-04-13 22:59 ` [PATCH v3 3/7] Factor page_endio() out of mpage_end_io() Matthew Wilcox
2014-04-13 22:59 ` [PATCH v3 4/7] Add bdev_read_page() and bdev_write_page() Matthew Wilcox
2014-04-13 22:59 ` [PATCH v3 5/7] swap: Use bdev_read_page() / bdev_write_page() Matthew Wilcox
2014-04-24 18:18   ` Andrew Morton
2014-04-24 18:57     ` Matthew Wilcox [this message]
2014-04-25 14:01       ` Matthew Wilcox
2014-04-13 22:59 ` [PATCH v3 6/7] brd: Add support for rw_page Matthew Wilcox
2014-04-13 22:59 ` [PATCH v3 7/7] brd: Return -ENOSPC rather than -ENOMEM on page allocation failure Matthew Wilcox
2014-04-14  0:08 ` [PATCH v3 0/7] Page I/O Minchan Kim

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