From: Chris Snook <csnook@redhat.com>
To: David Howells <dhowells@redhat.com>
Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org,
torvalds@linux-foundation.org, netdev@vger.kernel.org,
akpm@linux-foundation.org, ak@suse.de, heiko.carstens@de.ibm.com,
davem@davemloft.net, schwidefsky@de.ibm.com,
wensong@linux-vs.org, horms@verge.net.au, wjiang@resilience.com,
cfriesen@nortel.com, zlynx@acm.org, rpjday@mindspring.com,
jesper.juhl@gmail.com
Subject: Re: [PATCH 6/24] make atomic_read() behave consistently on frv
Date: Fri, 10 Aug 2007 15:54:19 -0400 [thread overview]
Message-ID: <46BCC26B.6080600@redhat.com> (raw)
In-Reply-To: <2708.1186737826@redhat.com>
David Howells wrote:
> Chris Snook <csnook@redhat.com> wrote:
>
>> To head off the criticism, I admit this is an oversimplification, and true
>> busy-waiters should be using cpu_relax(), which contains a barrier.
>
> Why would you want to use cpu_relax()? That's there to waste time efficiently,
> isn't it? Shouldn't you be using smp_rmb() or something like that?
>
> David
cpu_relax() contains a barrier, so it should do the right thing. For
non-smp architectures, I'm concerned about interacting with interrupt
handlers. Some drivers do use atomic_* operations.
-- Chris
next prev parent reply other threads:[~2007-08-10 19:54 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-08-09 13:41 [PATCH 6/24] make atomic_read() behave consistently on frv Chris Snook
2007-08-09 16:54 ` Chris Snook
2007-08-10 9:23 ` David Howells
2007-08-10 19:54 ` Chris Snook [this message]
2007-08-11 0:54 ` Herbert Xu
2007-08-11 0:54 ` Herbert Xu
2007-08-11 4:29 ` Paul E. McKenney
2007-08-13 5:15 ` Herbert Xu
2007-08-13 6:03 ` Paul E. McKenney
2007-08-14 5:34 ` Nick Piggin
2007-08-14 7:26 ` Herbert Xu
2007-08-14 17:01 ` Paul E. McKenney
2007-08-14 22:01 ` Arnd Bergmann
2007-08-14 22:43 ` Paul E. McKenney
2007-08-15 13:29 ` Arnd Bergmann
2007-08-15 15:06 ` Michael Buesch
2007-08-15 13:30 ` Nick Piggin
2007-08-15 20:15 ` Paul E. McKenney
2007-08-16 1:09 ` Nick Piggin
2007-08-16 2:27 ` Paul E. McKenney
2007-08-11 8:47 ` David Howells
2007-08-13 6:44 ` Chris Snook
2007-08-14 5:42 ` Nick Piggin
2007-08-15 18:51 ` Segher Boessenkool
2007-08-15 19:18 ` Paul E. McKenney
2007-08-15 19:46 ` Segher Boessenkool
2007-08-15 19:59 ` Paul E. McKenney
2007-08-15 20:13 ` Segher Boessenkool
2007-08-15 20:38 ` Paul E. McKenney
2007-08-15 21:15 ` Segher Boessenkool
2007-08-16 1:20 ` Nick Piggin
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