From: "Myklebust, Trond" <Trond.Myklebust@netapp.com>
To: Dave Kleikamp <dave.kleikamp@oracle.com>
Cc: "linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Zach Brown <zab@zabbo.net>,
"linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>
Subject: Re: [RFC PATCH 22/22] nfs: add support for read_iter, write_iter
Date: Mon, 27 Feb 2012 22:08:50 +0000 [thread overview]
Message-ID: <1330380530.5541.87.camel@lade.trondhjem.org> (raw)
In-Reply-To: <1330377576-3659-23-git-send-email-dave.kleikamp@oracle.com>
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On Mon, 2012-02-27 at 15:19 -0600, Dave Kleikamp wrote:
> This patch implements the read_iter and write_iter file operations which
> allow kernel code to initiate directIO. This allows the loop device to
> read and write directly to the server, bypassing the page cache.
>
> Signed-off-by: Dave Kleikamp <dave.kleikamp@oracle.com>
> Cc: Zach Brown <zab@zabbo.net>
> Cc: Trond Myklebust <Trond.Myklebust@netapp.com>
> Cc: linux-nfs@vger.kernel.org
Performance is going to be absolutely terrible for O_DIRECT bvecs if you
send just one page per RPC call. We are working on merging the O_DIRECT
and page cache code in order to give O_DIRECT the ability to coalesce
requests and do pNFS, and I'm hoping that code will be available soon.
In the meantime, wouldn't it be possible to add basic coalescing to
nfs_direct_read_schedule_bvec/nfs_direct_write_schedule_bvec more or
less in the same way that we do for multi-page iovec segments?
i.e. if the next bvec is contiguous with the previous, and the resulting
RPC read length < rsize / write length < wsize, then add it to the same
RPC call.
--
Trond Myklebust
Linux NFS client maintainer
NetApp
Trond.Myklebust@netapp.com
www.netapp.com
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next prev parent reply other threads:[~2012-02-27 22:08 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-27 21:19 [RFC PATCH 00/22] loop: Issue O_DIRECT aio with pages Dave Kleikamp
2012-02-27 21:19 ` [RFC PATCH 01/22] iov_iter: move into its own file Dave Kleikamp
2012-03-01 20:25 ` Jeff Moyer
2012-02-27 21:19 ` [RFC PATCH 02/22] iov_iter: add copy_to_user support Dave Kleikamp
2012-02-27 21:19 ` [RFC PATCH 03/22] fuse: convert fuse to use iov_iter_copy_[to|from]_user Dave Kleikamp
2012-02-28 9:09 ` Miklos Szeredi
2012-02-27 21:19 ` [RFC PATCH 04/22] iov_iter: hide iovec details behind ops function pointers Dave Kleikamp
2012-02-27 21:19 ` [RFC PATCH 05/22] iov_iter: add bvec support Dave Kleikamp
2012-02-27 21:19 ` [RFC PATCH 06/22] iov_iter: add a shorten call Dave Kleikamp
2012-02-27 21:19 ` [RFC PATCH 07/22] iov_iter: let callers extract iovecs and bio_vecs Dave Kleikamp
2012-02-27 21:19 ` [RFC PATCH 08/22] dio: create a dio_aligned() helper function Dave Kleikamp
2012-02-27 21:19 ` [RFC PATCH 09/22] dio: add dio_alloc_init() " Dave Kleikamp
2012-02-27 21:19 ` [RFC PATCH 10/22] dio: add sdio_init() " Dave Kleikamp
2012-02-27 21:19 ` [RFC PATCH 11/22] dio: add dio_lock_and_flush() helper Dave Kleikamp
2012-02-27 21:19 ` [RFC PATCH 12/22] dio: add dio_post_submission() helper function Dave Kleikamp
2012-02-27 21:19 ` [RFC PATCH 13/22] dio: add __blockdev_direct_IO_bdev() Dave Kleikamp
2012-02-27 22:16 ` Zach Brown
2012-02-27 21:19 ` [RFC PATCH 14/22] fs: pull iov_iter use higher up the stack Dave Kleikamp
2012-02-27 21:19 ` [RFC PATCH 15/22] aio: add aio_kernel_() interface Dave Kleikamp
2012-02-27 21:19 ` [RFC PATCH 16/22] aio: add aio support for iov_iter arguments Dave Kleikamp
2012-02-27 22:13 ` Zach Brown
2012-02-27 21:19 ` [RFC PATCH 17/22] bio: add bvec_length(), like iov_length() Dave Kleikamp
2012-02-27 21:19 ` [RFC PATCH 18/22] ext3: add support for .read_iter and .write_iter Dave Kleikamp
2012-02-27 22:34 ` Zach Brown
2012-02-27 23:14 ` Dave Kleikamp
2012-02-27 21:19 ` [RFC PATCH 19/22] ocfs2: add support for read_iter, write_iter, and direct_IO_bvec Dave Kleikamp
2012-02-27 21:19 ` [RFC PATCH 20/22] ext4: " Dave Kleikamp
2012-02-27 21:19 ` [RFC PATCH 21/22] btrfs: " Dave Kleikamp
2012-02-27 21:19 ` [RFC PATCH 22/22] nfs: add support for read_iter, write_iter Dave Kleikamp
2012-02-27 22:08 ` Myklebust, Trond [this message]
2012-02-27 23:17 ` Dave Kleikamp
2012-02-27 22:27 ` [RFC PATCH 00/22] loop: Issue O_DIRECT aio with pages Zach Brown
2012-02-27 22:53 ` Dave Kleikamp
2012-02-28 9:29 ` Christoph Hellwig
2012-02-28 15:14 ` Zach Brown
2012-02-29 9:08 ` Christoph Hellwig
2012-03-01 20:33 ` Jeff Moyer
2012-03-01 20:36 ` Dave Kleikamp
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