From: Jes Sorensen <jes@sgi.com>
To: "Bryan O'Sullivan" <bos@pathscale.com>
Cc: Andi Kleen <ak@suse.de>,
linux-kernel@vger.kernel.org, discuss@x86-64.org
Subject: Re: Why is wmb() a no-op on x86_64?
Date: 18 Jan 2006 12:06:39 -0500 [thread overview]
Message-ID: <yq04q41qxcw.fsf@jaguar.mkp.net> (raw)
In-Reply-To: <1137603169.4757.50.camel@serpentine.pathscale.com>
>>>>> "Bryan" == Bryan O'Sullivan <bos@pathscale.com> writes:
Bryan> On Wed, 2006-01-18 at 17:29 +0100, Andi Kleen wrote:
>> Why do you need the barrier?
Bryan> On x86_64, we fiddle with the MTRRs to enable write combining,
Bryan> which makes a huge difference to performance. It's not clear
Bryan> to me what we should even do on other architectures, since the
Bryan> only generic entry point that even exposes write combining is
Bryan> pci_mmap_page_range, which is for PCI mmap through userspace,
Bryan> and half the arches I've looked at ignore its write_combine
Bryan> parameter.
A job for mmiowb() perhaps?
Cheers,
Jes
next prev parent reply other threads:[~2006-01-18 17:06 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-01-18 16:23 Bryan O'Sullivan
2006-01-18 16:29 ` Andi Kleen
2006-01-18 16:52 ` Bryan O'Sullivan
2006-01-18 17:06 ` Jes Sorensen [this message]
2006-01-18 17:23 ` Bryan O'Sullivan
2006-01-18 17:31 ` [discuss] " Andi Kleen
2006-01-19 10:03 ` Jes Sorensen
2006-01-18 20:07 ` Roland Dreier
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=yq04q41qxcw.fsf@jaguar.mkp.net \
--to=jes@sgi.com \
--cc=ak@suse.de \
--cc=bos@pathscale.com \
--cc=discuss@x86-64.org \
--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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
all inboxes | Powered by JetHome®