From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Jeff Garzik <jgarzik@pobox.com>
Cc: Andrew Morton <akpm@osdl.org>, Linus Torvalds <torvalds@osdl.org>,
Linux Kernel list <linux-kernel@vger.kernel.org>,
list linux-ide <linux-ide@vger.kernel.org>
Subject: Re: page fault scalability patch V12 [0/7]: Overview and performance tests
Date: Thu, 02 Dec 2004 22:16:24 +1100 [thread overview]
Message-ID: <1101986184.14597.75.camel@gaston> (raw)
In-Reply-To: <41AEC021.8040000@pobox.com>
On Thu, 2004-12-02 at 02:11 -0500, Jeff Garzik wrote:
> Benjamin Herrenschmidt wrote:
> > They may not end up in order if they are stores (the stores to the
> > taskfile may be out of order vs; the loads/stores to/from the data
> > register) unless you have a spinlock protecting both or a full sync (on
> > ppc), but then, I don't know the ordering things on x86_64. This could
> > certainly be a problem on ppc & ppc64 too.
>
>
> Is synchronization beyond in[bwl] needed, do you think?
Yes, when potentially hop'ing between CPUs, definitely.
> This specific problem is only on Intel ICHx AFAICS, which is PIO not
> MMIO and x86-only. I presumed insw() by its very nature already has
> synchronization, but perhaps not...
Hrm... on "pure" x86, I would expect so at the HW level, not sure about
x86_64... but there would be definitely an issue on ppc with your
scheme. You need at least a full barrier before you trigger the
workqueue. That may not be the problem you are facing now, but it would
become one.
Ben.
next prev parent reply other threads:[~2004-12-02 11:17 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <Pine.LNX.4.44.0411221457240.2970-100000@localhost.localdomain>
[not found] ` <Pine.LNX.4.58.0411221343410.22895@schroedinger.engr.sgi.com>
[not found] ` <Pine.LNX.4.58.0411221419440.20993@ppc970.osdl.org>
[not found] ` <Pine.LNX.4.58.0411221424580.22895@schroedinger.engr.sgi.com>
[not found] ` <Pine.LNX.4.58.0411221429050.20993@ppc970.osdl.org>
[not found] ` <Pine.LNX.4.58.0412011539170.5721@schroedinger.engr.sgi.com>
[not found] ` <Pine.LNX.4.58.0412011608500.22796@ppc970.osdl.org>
[not found] ` <41AEB44D.2040805@pobox.com>
[not found] ` <20041201223441.3820fbc0.akpm@osdl.org>
2004-12-02 7:00 ` page fault scalability patch V12 [0/7]: Overview and performance tests Jeff Garzik
2004-12-02 7:05 ` Benjamin Herrenschmidt
2004-12-02 7:11 ` Jeff Garzik
2004-12-02 11:16 ` Benjamin Herrenschmidt [this message]
2004-12-02 14:30 ` Andy Warner
2005-01-06 23:40 ` Jeff Garzik
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