caching - How to mark some memory ranges as non-cacheable from C++?

Question

I was reading the wikipedia on the CPU cache here: http://en.wikipedia.org/wiki/CPU_cache#Replacement_Policies

Marking some memory ranges as non-cacheable can improve performance, by avoiding caching of memory regions that are rarely re-accessed. This avoids the overhead of loading something into the cache, without having any reuse.

Now, I've been reading and learning about how to write programs with better cache performance (general considerations, usually not specific to C++), but I did not know that high-level code can interact with CPU caching behavior explicitly. So my question, is there a way to do what I quoted from that article, in C++?

Also, I would appreciate resources on how to improve cache performance specifically in C++, even if they do not use any functions that deal directly with the CPU caches. For example, I'm wondering if using excessive levels of indirection (eg., a container of pointers to containers of pointers) can damage cache performance.

Answer 1

On Windows, you can use VirtualProtect(ptr, length, PAGE_NOCACHE, &oldFlags) to set the caching behavior for memory to avoid caching.

Regarding too many indirections: Yes, they can damage cache performance, if you access different pieces of memory very often (which is what happens usually). It's important to note, though, that if you consistently dereference the same set of e.g. 8 blocks of memory, and only the 9th block differs, then it generally won't make a difference, because the 8 blocks would be cached after the first access.