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Interviewing Intel's Chief Architect of x86 Cores
- gjvc 1y ago[flagged]
- reitzensteinm 1y agoI'm not going to thumb my nose at CPU design content from folks that aren't good at public speaking. They're almost entirely distinct skill sets.
- actionfromafar 1y agoAlso, the Venn Diagram between (good public speech) and (good public speech which also looks good when transcribed) is probably pretty thin.
- saagarjha 1y agoIt's basically a transcript of a conversation, so obviously it's not going to read as edited prose.
- gjvc 1y agomy original point stands
- Oleh_h 1y agoYeah, that's weird.
- brucehoult 1y agoOh em gee ... what a contentless interview. "We made it wider and deeper". Gosh. Why didn't anyone think about doing that before?
- saagarjha 1y agoBecause that costs power and area.
- brucehoult 1y agoAnd it still does. And the last generation was wider and deeper than the one before it, also costing power and area. The question that should be asked ... but which would never be answered ... is "What was it that you changed that REQUIRED and ALLOWED you to go wider and deeper?" It's not a new process node every time. Theres no NEED to have a massive reorder buffer unless you can decode and dispatch that number of instructions in the time it takes for a load to arrive from whichever level of memory hierarchy you're optimising for. And there's no POINT if you're often going to get a misprediction in that number of instructions. Ok, so wider decode is one component of that. Is there a difference in memory latency as well? Wider decode past 3 or 4 instructions increasingly means that you can't just end your packet of decoded instructions at the first branch -- as you get wider you're increasingly going to have to both parse past a conditional branch, and then have to predict more than one branch in the same decode cycle. You'll also get into branches that jump to other instructions in the same decode group (either forward or backward). There are all kinds of complications there, with no doubt interesting solutions, that go far beyond "we went wider and deeper".
- deleted 1y ago[deleted]
- porridgeraisin 1y agohttps://chatgpt.com/share/68ef6cc3-1c48-8013-a545-905af89fbcd3 https://chatgpt.com/share/68ef6cc3-1c48-8013-a545-905af89fbc... I asked chatgpt to give a contentful summary of the interview, it seems to be more or less accurate, albeit surface level. If anyone is interested. It gets the "why" but not the "how". Maybe someone here can prompt it further to speculate on the "how". I don't think I'll be able to verify its output well enough to do that.
- 1y ago
- norin 1y agoyeah strange sort of
- BoredPositron 1y agoOdd read especially after that preamble >> The transcript has been edited for readability and conciseness. Not a lot of novel information either.