Subject: Re: [boost] Cache flushing in the constructors
From: Thomas Klimpel (Thomas.Klimpel_at_[hidden])
Date: 2010-08-04 10:19:57
Sid Sacek wrote:
> >> Why would you need to worry about such a thing?
> >> That's the responsibility of the compiler/hardware.
> >> Rob Stewart
>
>
> Are you sure the compiler would take care of this?
>
> I've worked on a number of different CPU's, including the SPARC and the
> RS/6000, and I've never seen any special assembly emitted by the
> compiler that would do that. I feel like there's still something
> missing from the picture.
How familiar are you with the term ccNUMA? As I'm not too familiar with it myself, I just did a quick look up at wikipedia (<http://en.wikipedia.org/wiki/Non-Uniform_Memory_Access>):
Cache coherent NUMA (ccNUMA)
Nearly all CPU architectures use a small amount of very fast non-shared memory known as cache to exploit locality of reference in memory accesses. With NUMA, maintaining cache coherence across shared memory has a significant overhead.
Although simpler to design and build, non-cache-coherent NUMA systems become prohibitively complex to program in the standard von Neumann architecture programming model. As a result, all NUMA computers sold to the market use special-purpose hardware to maintain cache coherence[citation needed], and thus class as "cache-coherent NUMA", or ccNUMA.
In case this information is correct, I see little reason why you or your compiler would need to generate extra code.
Regards,
Thomas