From: Chris Snook <csnook@redhat.com>
To: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org,
torvalds@linux-foundation.org
Cc: 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: Thu, 09 Aug 2007 12:54:10 -0400 [thread overview]
Message-ID: <46BB46B2.60808@redhat.com> (raw)
In-Reply-To: <20070809134150.GA14890@shell.boston.redhat.com>
Chris Snook wrote:
> From: Chris Snook <csnook@redhat.com>
>
> Make atomic_read() volatile on frv. This ensures that busy-waiting
> for an interrupt handler to change an atomic_t won't get compiled to an
> infinite loop, consistent with SMP architectures.
To head off the criticism, I admit this is an oversimplification, and true
busy-waiters should be using cpu_relax(), which contains a barrier. As
discussed in recent threads, there are other cases which can be optimized by
removing the need for a barrier, and having behavior consistent with
architectures where the benefit is more profound is also valuable.
-- Chris
next prev parent reply other threads:[~2007-08-09 17:00 UTC|newest]
Thread overview: 30+ 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 [this message]
2007-08-10 9:23 ` David Howells
2007-08-10 19:54 ` Chris Snook
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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