On a modern x86 with a large L3 cache it is entirely possible that I will write a block of data into L3 cache, then read it, and then never access it again. I would like to free the space it occupies in cache without writing it back to memory (since RAM bandwidth is a limiting constraint for my application). I know that overwriting it before it is written will work, but that only helps if I have some useful data ready to overwrite it with.
Is there any way to just tell the CPU that I don't care about the contents of those addresses any more?