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Memory part 2: CPU caches

Memory part 2: CPU caches

Posted Oct 10, 2007 11:40 UTC (Wed) by dlang (subscriber, #313)
In reply to: Memory part 2: CPU caches by pr1268
Parent article: Memory part 2: CPU caches

one of the huge advantages of hyperthreading is that a result of the tratment of CPU registers. if you schedule two threads on one core you have to save and restore all the registers (possibly as far as main memory, depending on what your second thread does to your cache)

but with hyperthreading each virtual core has it's own set of registers, this provides a drastic speedup when switching from one task to another (under ideal situations)

in the real world it all depends on how the different threads compete for cache space and memory I/O. if you are building a dedicated compute cluster (and some high-end graphics workstations fit in this catagory) you can tune for this and get really good speedups, if you are running a mixed hodgepodge of stuff you are far more likely to hit the problem cases.


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