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can anyone explain what is load buffer and how it's different from invalidation queues. and also difference between store buffers and write combining buffers? The paper by Paul E Mckenny http://www.rdrop.com/users/paulmck/scalability/paper/whymb.2010.07.23a.pdf explains very nicely about the store buffers and invalidation queues but unfortunately doesn't talk about write combining buffers
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pH buffer solutions should always be stored in a cool dry place and should be discarded responsibly if any remains after the expiry date, which is printed on the bottle.
A write buffer is a type of data buffer that can be used to hold data being written from the cache to main memory or to the next cache in the memory hierarchy to improve performance and reduce latency. It is used in certain CPU cache architectures like Intel's x86 and AMD64.
A queue is a set of first-in, first-out (FIFO) buffers that buffer packets on the data path. QoS associates queues with a traffic class/interface pair. For example, if you create 4000 IP interfaces and configure each interface with four traffic classes, then 16,000 queues are created.
The write buffer is used for all writes to a noncacheable, bufferable region, write-through region, and write misses to a write-back region. A separate buffer is incorporated in the DCache for holding write-back data for cache line evictions or cleaning of dirty cache lines.
An invalidate queue is more like a store buffer, but it's part of the memory system, not the CPU. Basically it is a queue that keeps track of invalidations and ensures that they complete properly so that a cache can take ownership of a cache line so it can then write that line. A load queue is a speculative structure that keeps track of in-flight loads in the out of order processor. For example, the following can occur
A store buffer is a speculative structure that exists in the CPU, just like the load queue and is for allowing the CPU to speculate on stores. A write combining buffer is part of the memory system and essentially takes a bunch of small writes (think 8 byte writes) and packs them into a single larger transaction (a 64-byte cache line) before sending them to the memory system. These writes are not speculative and are part of the coherence protocol. The goal is to save bus bandwidth. Typically, a write combining buffer is used for uncached writes to I/O devices (often for graphics cards). It's typical in I/O devices to do a bunch of programming of device registers by doing 8 byte writes and the write combining buffer allows those writes to be combined into larger transactions when shipping them out past the cache.
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