multi-core software

[Raymond Wiker]

Roedy Green <see_website at mindprod.com.invalid> writes:

> On Fri, 5 Jun 2009 18:15:00 +0000 (UTC), Kaz Kylheku
> <kkylheku at gmail.com> wrote, quoted or indirectly quoted someone who
> said :
>
>>Even for problems where it appears trivial, there can be hidden
>>issues, like false cache coherency communication where no actual
>>sharing is taking place. Or locks that appear to have low contention and
>>negligible performance impact on ``only'' 8 processors suddenly turn into
>>bottlenecks. Then there is NUMA. A given address in memory may be
>>RAM attached to the processor accessing it, or to another processor,
>>with very different access costs.
>
> Could what you are saying be summed up by saying, "The more threads
> you have the more important it is to keep your threads independent,
> sharing as little data as possible."

	Absolutely... not a new observation, either, as it follows
directly from Amdahl's law.