From: Peter Zijlstra <peterz@infradead.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: David Daney <ddaney@caviumnetworks.com>,
Ralf Baechle <ralf@linux-mips.org>,
"linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
linux-mips <linux-mips@linux-mips.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Paul McKenney <paulmck@linux.vnet.ibm.com>,
Will Deacon <will.deacon@arm.com>
Subject: Re: mips octeon memory model questions
Date: Tue, 4 Feb 2014 20:05:35 +0100 [thread overview]
Message-ID: <20140204190535.GC5002@laptop.programming.kicks-ass.net> (raw)
In-Reply-To: <CA+55aFz9+AtK_OnUhH0gspUsXLxZN-MRwKVR5zVPsVGmGpBqxg@mail.gmail.com>
On Tue, Feb 04, 2014 at 10:58:40AM -0800, Linus Torvalds wrote:
> On Tue, Feb 4, 2014 at 10:41 AM, Peter Zijlstra <peterz@infradead.org> wrote:
> >
> > Still doesn't make sense, because if we need the first sync to stop
> > writes from being re-ordered with the ll-sc, we also need the second
> > sync to avoid the same.
>
> Presumably octeon doesn't do speculative writes, only *buffered* writes.
Speculative writes are bad.. :-)
> So writes move down, not up.
Right, but the ll-sc store might move down over a later store. Say
because the ll-sc needs to first get exclusive ownership of the
cacheline where the later store would be to an already owned line.
next prev parent reply other threads:[~2014-02-04 19:05 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-02-04 18:41 mips octeon memory model questions Peter Zijlstra
2014-02-04 18:58 ` Linus Torvalds
2014-02-04 19:05 ` Peter Zijlstra [this message]
2014-02-04 19:16 ` Linus Torvalds
2014-02-04 19:39 ` Peter Zijlstra
2014-02-04 19:51 ` David Daney
2014-02-04 19:51 ` David Daney
2014-02-06 11:45 ` Peter Zijlstra
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