How many bytes does a Xeon bring into the cache per memory access?

Question

I am working on a system, written in C++, running on a Xeon on Linux, that needs to run as fast as possible. There is a large data structure (basically an array of structs)

Answer 1

Old SO question that has some info that might be of use to you (in particular the first answer where to look for Linux CPU info - responder doesn't mention line size proper, but 'other info' on top of associativity etc). Question is for x86, but answers are more general. Worth a look.

Where is the L1 memory cache of Intel x86 processors documented?