From: Dave Kleikamp <dave.kleikamp@oracle.com>
To: Zach Brown <zab@zabbo.net>
Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH 00/22] loop: Issue O_DIRECT aio with pages
Date: Mon, 27 Feb 2012 16:53:09 -0600 [thread overview]
Message-ID: <4F4C0955.6060907@oracle.com> (raw)
In-Reply-To: <4F4C036A.2080808@zabbo.net>
On 02/27/2012 04:27 PM, Zach Brown wrote:
> On 02/27/2012 04:19 PM, Dave Kleikamp wrote:
>> This patchset was begun by Zach Brown and was originally submitted for
>> review in October, 2009.
>
> Man, it's been a while. I remembered almost none of the details of this
> work when I read your introductory message. As I read the patches it
> all came flooding back, though. Yikes :).
>
> My biggest fear about this patch series is the sheer amount of very
> fiddly code motion. I remember spending a lot of time verifying that
> the patches didn't accidentally lose new changes as the patches were
> ported to newer kernels.
>
> Has someone gone through these most recent patches with an absurdly fine
> toothed comb? The patches that touch fs/direct-io.c and mm/filemap.c
> are the most risky, by far.
I was pretty careful porting these patches, trying not to lose the
effects of any newer changes to the affected functions. It wouldn't hurt
to go through them again, but I am putting it out as an RFC since I
don't think these are ready to merge quite yet.
>> This series was written to reduce the current overhead loop imposes by
>> performing synchronus buffered file system IO from a kernel thread.
>> These
>> patches turn loop into a light weight layer that translates bios into
>> iocbs.
>
> It'd be worth including some simple benchmark results, I think. I
> remember testing with concurrent O_DIRECT aio with fio on a loopback
> device on top of files in each underlying file system.
Actually, some preliminary tests I ran showed a significant slowdown. I
suspect it may have to do with the unconditional setting of O_DIRECT,
but I haven't verified that yet. I'll do further performance analysis,
but I wanted to get some eyes on this in the mean time.
Thanks,
Shaggy
next prev parent reply other threads:[~2012-02-27 22:53 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
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 [this message]
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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