On Fri, 9 Jul 2010, Gabor PALI wrote:
On 06/18/10 14:08, Robert Watson wrote:
The only reservation I have, really, is that 64-bit writes are
non-atomic on
i386 and other 32-bit architectures (or, at least, I think they are).
This
means DPCPU_SUM may encounter non-atomicity rather than just staleness
in the
values it reads as it iterates. That said, we should probably use 64-bit
anyway, because 32-bit counters are gauche. :-)
What is about introducing 64-bit atomic counters?
There's no native 64-bit atomic add primitive on most 32-bit platforms;
however, I think I have an e-mail in my in queue from you suggesting an
alternative approach that I haven't yet gotten to due to utter saturation
here. 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.
Robert
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