Why Apple ditched PowerPC, and what it says about Apple ditching Intel

Re:Why Apple ditched PowerPC, and what it says about Apple d... by perl4ever on Saturday June 20, 2020 @04:00PM (#23586747)

I was thinking single thread though.

My guess is that there are now a lot of forms of hardware acceleration of specific things that make your daily experience seem faster, but I haven't seen them catalogued and put in perspective with measurements.

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Re:Why Apple ditched PowerPC, and what it says about Apple d... by Someone on Saturday June 20, 2020 @04:25PM (#23586976)

Single-threaded doesn’t imply IPC can’t go up or go above 1. See https://en.m.wikipedia.org/wiki/Superscalar_processor.

I would think that and cache size are large differences between a P4 and the i7 running at about the same clock frequency.

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Re:Why Apple ditched PowerPC, and what it says about Apple d... by innocenat on Saturday June 20, 2020 @11:46PM (#23589586)

i7 can regularly archive 2-3ipc easily.

I haven't read about P4 and NetBurst in a long t ime, but is mu memory serve me right, P4 is usually less than 1ipc due to its very long pipeline (31 stages IIRC) that is very prone to pipeline stall. Modern processor can also do many thing faster. I think P4 takes ~110 cycles for integer division, while modern cpu can do in ~30-40 cycles. And IIRC, P4 cannot flush the division unit so if branch/jump prediction is wrong and division is speculated, it was to wait until the division unit finish computation before it can resume execution.

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