linux-kernel - Re: [PATCH v3 5/7] swap: Use bdev_read_page() / bdev_write

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Message-ID: <20140425140100.GF5886@linux.intel.com>
Date:	Fri, 25 Apr 2014 10:01:01 -0400
From:	Matthew Wilcox <willy@...ux.intel.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Matthew Wilcox <matthew.r.wilcox@...el.com>,
	linux-fsdevel@...r.kernel.org, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, Hugh Dickins <hughd@...gle.com>
Subject: Re: [PATCH v3 5/7] swap: Use bdev_read_page() / bdev_write_page()

On Thu, Apr 24, 2014 at 02:57:40PM -0400, Matthew Wilcox wrote:
> By calling the device driver to write the page directly, we avoid
> allocating a BIO, which allows us to free memory without allocating
> memory.

I got handed some performance numbers last night!  Next time you're updating
the patch description, please use:

By calling the device driver to write the page directly, we avoid
allocating a BIO, which allows us to free memory without allocating
memory.  When running a swap-heavy benchmark, system time is reduced by
about 20%.

Tested-by: Dheeraj Reddy <dheeraj.reddy@...el.com>
Signed-off-by: Matthew Wilcox <matthew.r.wilcox@...el.com>
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