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To: Gabor PALI <pgj@FreeBSD.org>
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Subject: Re: svn commit: r209119 - head/sys/sys
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On 9 Jul 2010, at 19:58, Gabor PALI wrote:

>>  I assume there are reasonable alternatives that work around the
>> potential race with a small probability of a missed or extra update,
>> or similar, which would be fine.
>=20
> In a few words: As far as I know, 64-bit atomic counters could be
> implemented by using cmpxchg8b or by a plain uint64_t variable =
protected
> by some kind of locking(9).

If we can do it in one atomic in the common case, and two atomics in an =
edge case, that sounds fine. I think any use of locking(9) would be =
sufficiently costly as to not be worth the improvements in consistency, =
given the frequency of statistics operations.

Robert=