Messages in this thread | | | Date | Thu, 21 Feb 2013 23:15:50 +0100 | Subject | Re: [RFC/PATCH 2/5] kernel_cpustat: convert to atomic 64-bit accessors | From | Frederic Weisbecker <> |
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2013/2/21 Russell King - ARM Linux <linux@arm.linux.org.uk>: > 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().
Right.
> 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.
Yeah but that's the generic version. I guess the archs that have overriden don't take any locks there.
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