On 1/31/2014 9:52 AM, Charles Mills wrote:
I don't really know, but my conclusion is that either "getting interrupted" consumes a fair amount of CPU time, or else that if the program is busy continuously it tends to "own" the instruction and data caches, which saves a lot of CPU time.
Both. We've measured a so-called "task switch" at ~4000 instructions (we use the "L" instruction as our metric). And, on modern hardware, cache and TLB misses are "killer." A memory operand reference is literally _orders of magnitude_ slower than an in-L1-cache operand reference.
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