From: Christoph Hellwig <hch@lst.de>
To: Jamie Lokier <jamie@shareable.org>
Cc: Christoph Hellwig <hch@lst.de>, qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH 2/3] barriers: block-raw-posix barrier support
Date: Tue, 5 May 2009 15:29:44 +0200 [thread overview]
Message-ID: <20090505132944.GA3416@lst.de> (raw)
In-Reply-To: <20090505123311.GD25328@shareable.org>
On Tue, May 05, 2009 at 01:33:11PM +0100, Jamie Lokier wrote:
> You don't need two fdatasyncs if the barrier request is just a
> barrier, no data write, used only to flush previously written data by
> a guest's fsync/fdatasync implementation.
Yeah. I'll put that optimization in after some testing.
> This is the best argument yet for having distinct "barrier" and "sync"
> operations. "Barrier" is for ordering I/O, such as journalling
> filesystems.
Doesn't really help as long as we're using the normal Posix filesystem
APIs on the host. The only way to guarantee ordering of multiple
*write* systen calls is to call f(data)sync between them.
next prev parent reply other threads:[~2009-05-05 13:29 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-05-05 12:08 [Qemu-devel] [PATCH 0/3] write barrier support Christoph Hellwig
2009-05-05 12:08 ` [Qemu-devel] barriers: block layer preparations Christoph Hellwig
2009-05-05 13:51 ` Avi Kivity
2009-05-05 15:38 ` Jamie Lokier
2009-05-05 15:49 ` Avi Kivity
2009-05-05 16:00 ` Jamie Lokier
2009-05-05 20:57 ` Christoph Hellwig
2009-05-05 22:49 ` Jamie Lokier
2009-05-05 12:08 ` [Qemu-devel] [PATCH 2/3] barriers: block-raw-posix barrier support Christoph Hellwig
2009-05-05 12:33 ` Jamie Lokier
2009-05-05 13:29 ` Christoph Hellwig [this message]
2009-05-05 16:00 ` Jamie Lokier
2009-05-05 12:09 ` [Qemu-devel] [PATCH 3/3] barriers: virtio Christoph Hellwig
2009-05-05 13:53 ` [Qemu-devel] [PATCH 0/3] write barrier support Avi Kivity
2009-05-05 21:00 ` Christoph Hellwig
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20090505132944.GA3416@lst.de \
--to=hch@lst.de \
--cc=jamie@shareable.org \
--cc=qemu-devel@nongnu.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.