From: Jeff Garzik <jeff@garzik.org>
To: Jeff Moyer <jmoyer@redhat.com>
Cc: Linux Kernel Mailing <linux-kernel@vger.kernel.org>,
Jens Axboe <jens.axboe@oracle.com>
Subject: Re: blkdev_issue_flush really issues a WRITE_BARRIER -- is that okay?
Date: Mon, 12 Oct 2009 14:38:08 -0400 [thread overview]
Message-ID: <4AD37790.8090404@garzik.org> (raw)
In-Reply-To: <x49hbu4semq.fsf@segfault.boston.devel.redhat.com>
On 10/12/2009 01:31 PM, Jeff Moyer wrote:
> Hi,
>
> While looking though Christoph's patch to call blkdev_issue_flush for
> fsync on block devices, I noticed that it only issues a WRITE_BARRIER.
> I don't see how that guarantees that data is on stable storage. Am I
> missing something? Shouldn't this translate to a FLUSH CACHE or
> SYNCHRONIZE CACHE command?
Barriers are a high level primitive that exist at the block layer level.
Lower level storage drivers then convert barriers to a hardware-specific
low level primitive such as SYNCHRONIZE CACHE or FUA.
Jeff
prev parent reply other threads:[~2009-10-12 18:38 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-10-12 17:31 blkdev_issue_flush really issues a WRITE_BARRIER -- is that okay? Jeff Moyer
2009-10-12 18:38 ` Jeff Garzik [this message]
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=4AD37790.8090404@garzik.org \
--to=jeff@garzik.org \
--cc=jens.axboe@oracle.com \
--cc=jmoyer@redhat.com \
--cc=linux-kernel@vger.kernel.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.