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To: EricRR who wrote (107926)	8/21/2000 7:22:04 PM
From: Scumbria	Read Replies (1) \| Respond to of 186894

Ratbert, Sharky reports that Willy's branch prediction is 30% better than P3. If true, what does this mean for IPC? It will improve it somewhat, but I am dubious about the claim. Most code has about 10-20% inherently unpredictable branches. The real issue with branch prediction is not just the taken/not taken status, but also the prediction of the branch target address. There is no way to "predict" the impact of the alleged improvement, without more details. Scumbria

To: EricRR who wrote (107926)	8/21/2000 7:32:46 PM
From: Tenchusatsu	Read Replies (3) \| Respond to of 186894

Ratbert, <70% x2 pipeline size comes out to 140% percent branch penalty> Don't forget that part of the penalty is reduced thanks to the Execution Trace Cache. Instead of having to decode instructions again from the mispredicted branch onward, the pipeline can immediately be filled with predecoded instructions in program order. Also remember that Pentium III's pipeline was 12-14 stages, not 10 stages as you are assuming in your "x2 pipeline" phrase. Tenchusatsu