Memory 访问粒度与缓存行

Question

I'm trying to note the concept of memory access granularity , which I've found mentioned in some articles.

It's being said that memory access granularity is [ 1 ]:

the size in which a processor accesses memory

On the other hand, the cache line is [ 2 ]:

the unit of data transfer between cache and memory

• How does the size of a cache line relate to the granularity of the memory?
• Do they mean the same thing?

Thanks!

Answer 1

It seems like the memory access granularity is a more broad term and it can be applied to any kind of memory. Therefore, the cache line size is simply a granularity of the on-chip caches[ 1 ].

Quote from the link:

In most modern systems, the memory subsystem is managed and accessed at multiple different granularities at various resources. The software stack typically accesses data at a word granularity (typically 4 or 8 bytes). The on-chip caches store data at a cache line granularity (typically 64 bytes).