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Date: Thu, 21 Feb 2013 21:58:50 +0000
From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Kevin Hilman <khilman@linaro.org>,
        Mats Liljegren <mats.liljegren@enea.com>, linaro-dev@lists.linaro.org,
        linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org
Subject: Re: [RFC/PATCH 2/5] kernel_cpustat: convert to atomic 64-bit
	accessors
Message-ID: <20130221215850.GC17833@n2100.arm.linux.org.uk>
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On Thu, Feb 21, 2013 at 10:53:07PM +0100, Frederic Weisbecker wrote:
> That too should be kcpustat_this_cpu_set(), or kcpustat_this_cpu_add()
> FWIW. But we probably don't need the overhead of atomic_add() that
> does a LOCK.
> atomic_set(var, atomic_read(var) + delta) would be better. All we need

You mean atomic64_set() and atomic64_read().  Looking at the generic
version in lib/atomic64.c, atomic64_add() is cheaper for 32-bit arches
because it doesn't involve taking the lock twice.