Re: [PATCH 1/2] lib: Provide generic atomic64_t implementation

Avi Kivity
2009-06-14T11:53:33Z

Linus Torvalds wrote:
> On Sat, 13 Jun 2009, Linus Torvalds wrote:
>
>> On Sat, 13 Jun 2009, Paul Mackerras wrote:
>>
>>> Linus, Andrew: OK if this goes in via the powerpc tree?
>>>
>> Ok by me.
>>
>
> Btw, do 32-bit architectures really necessarily want 64-bit performance
> counters?
>
> I realize that 32-bit counters will overflow pretty easily, but I do
> wonder about the performance impact of doing things like hashed spinlocks
> for 64-bit counters. Maybe the downsides of 64-bit perf counters on such
> architectures might outweight the upsides?
>

An alternative implementation using 64-bit cmpxchg will recover most of
the costs of hashed spinlocks. I assume most serious 32-bit
architectures have them?

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error compiling committee.c: too many arguments to function