From: David Howells <dhowells@redhat.com>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: dhowells@redhat.com, Ingo Molnar <mingo@elte.hu>,
Paul Mackerras <paulus@samba.org>,
Arnaldo Carvalho de Melo <acme@infradead.org>,
Frederic Weisbecker <fweisbec@gmail.com>,
Steven Rostedt <rostedt@goodmis.org>,
David Miller <davem@davemloft.net>,
Paul Mundt <lethal@linux-sh.org>,
Will Deacon <will.deacon@arm.com>,
Deng-Cheng Zhu <dengcheng.zhu@gmail.com>,
LKML <linux-kernel@vger.kernel.org>,
linux-arch@vger.kernel.org
Subject: Re: [PATCH 1/4] arch: local64_t
Date: Fri, 21 May 2010 15:52:29 +0100 [thread overview]
Message-ID: <23895.1274453549@redhat.com> (raw)
In-Reply-To: <20100521135944.884367426@chello.nl>
Peter Zijlstra <a.p.zijlstra@chello.nl> wrote:
> + * This is the default implementation, which uses atomic64_t. Which is
> + * rather pointless. The whole point behind local64_t is that some processors
> + * can perform atomic adds and subtracts in a manner which is atomic wrt IRQs
> + * running on this CPU. local64_t allows exploitation of such capabilities.
Interesting... What FRV does in atomic64-ops.S should probably be rebranded
local64_t, and atomic64_t ops be based on that in non-SMP mode.
What I did on FRV was to emulate LL/ST instructions using some of the
excessive numbers of conditional bits to do so - but it only works on UP
systems.
David
prev parent reply other threads:[~2010-05-21 14:53 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20100521134205.781916350@chello.nl>
2010-05-21 13:42 ` [PATCH 1/4] arch: local64_t Peter Zijlstra
2010-05-21 14:47 ` Kyle McMartin
2010-05-21 14:52 ` David Howells [this message]
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