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This is a great presentation that goes over modern hardware. It's primarily about cache misses and their impact on performance. Below are some notes on the presentation (time - note).

14:30 - cache hit take 2/3 clocks - miss to memory take 200/300 clocks - 100X cost

15:20 - in multicore you hit l3 because of bandwidth & 1 ft of wire is 1 ghz clock

18 minutes - shadow processing; kind of how the cray does ii

25:30 - out of order execution & cache miss

30 - results - 7 ops out of 300 due to cache miss

33 - miss rates are low; but a tiny (5%) missrate dominates performance

52:20 - cahce misses are hard to detect; they just look like busy cpu top doesn't help...

An oldie but a goodie.