Re:Windows for Arm on M1 Mac Successfully Virtualized
by api on Friday November 27, 2020 @05:18PM
(#25233055)
Not true from what I’ve read. The problem with x86 is not complexity but variable instruction lengths. This makes it hard to determine instruction boundaries, complicating decoders and making more than 4-way decode hard. M1 has 8 decoders for comparison, and it would be easy to have 100 with ARM if there were a benefit to that many.
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Re:Windows for Arm on M1 Mac Successfully Virtualized
by bryanlarsen on Friday November 27, 2020 @07:15PM
(#25233836)
1. AMD64 is a lot easier to decode than the legacy i86 8/16/32 bit instruction set.
2. Decoding took a significant portion of the chip when they were a million transistors. The m1 has 16 billion resistors, decoding is a much less significant fraction of the chip.
Re:Windows for Arm on M1 Mac Successfully Virtualized
by petra on Friday November 27, 2020 @08:00PM
(#25234140)
Complexity isn't only about transistors, but also about delay.
And sure, there's pipelining but than your limited by latency.
Re:Windows for Arm on M1 Mac Successfully Virtualized
by ben-schaaf on Friday November 27, 2020 @08:17PM
(#25234238)
> The limitation of the x86 decoder is that each clock cycle can only process up to 4 instructions, but if it is a familiar instruction, it can be placed in the operation cache, and 8 instructions can be processed per cycle.
http://www.apothetech.com/amd-zen-3-vs-zen-2-amd-zen-3-is-39...