Cant the cache coherence just keeps the content in the caches synchronized without going to the memory (unless the cache line is truly evicted ofcourse)? I mean if one core is constantly reading and the other constantly writing, why not keep the data in the cache memory, and keep updating the data in the cache. Now what I don't understand is why the data needs to be written in the main memory. This may not be justified when the type of applications in the target domain exhibit very little writes to shared cache lines. Therefore, for smaller cache lines, the relative area overhead of MOESI increases. The data to main memory and changing the cache line to the Shared state. However, MESI only requires 2 bits per cache line to hold the state, while MOESI requires 3 bits per cache line. It confirms that each copy of a data block among the caches of the processors has a consistent value. local cache memory of each processor and the common memory shared by the processors. Typically done by forcing the read to back off (i.e. Cache Coherence assures the data consistency among the various memory blocks in the system, i.e. For example, 1) they use a global serializing point to serialize transactions, 2) they designed a lot messaging types such as INV, RESP and so on. Coherence rules: writes eventually become visible to all processors writes to the same location are serialized. The techniques and protocols from this paper are similar to the exisiting ones. Cache coherence is to ensure that the changes in the values of shared operands are propagated throughout the system in a timely fashion. Now that article says this at one place.Ī cache that holds a line in the Modified state must snoop (intercept) allĪttempted reads (from all of the other caches in the system) of theĬorresponding main memory location and insert the data that it holds. In this work, the add MESI coherence to these private L1 caches, as in they can make multiple L1 cache cache-coherent. I was reading about the MESI snooping cache coherence protocol, which I guess is the protocol that is used in modern multicore x86 processors (please correct me if I'm wrong).
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |