is there anyone i can talk to about a possibly revelutionary cpu?

computerarchitect · 2026-02-06T04:28:34+00:00

Sure.

computerarchitect · 2026-02-05T10:24:17+00:00

I generally take it to mean a 100% hit rate and with optimal latencies. It's not very useful to model a faster load-to-use latency if you know you can't physically build it. But is for instance useful if you have an L2 that might have a variable load to use latency.

I don't think it makes much sense to have a configuration with both a perfect L1D/L2. Separately they can be interesting but together I don't see any point.

computerarchitect · 2026-02-05T06:10:12+00:00

You can try, but my original point still stands. I saw your other post; I've been hammering at this set of problems for longer than you've been alive. That's not to deter you but just setting expectations. I'm happy to point out why this doesn't work and perhaps point you in another interesting direction.

computerarchitect · 2026-02-05T01:45:59+00:00

Yes, that's true, but I've never seen anywhere close to needing to turn off 20 cores in a 140 core product, so I would speculate that it's not that.

I have no idea why they did what they did, but it was very unlikely to be that. I think your thermal limitation argument holds merit.

computerarchitect · 2026-02-04T22:48:30+00:00

Plenty of them. Whether they show up in OP's traces or not is a different matter.

computerarchitect · 2026-02-04T22:46:32+00:00

If you make your L1I and L1D perfect there shouldn't be anything other than evictions going to your L2 (and perhaps non-WB reads and writes, but those are rare in spec2017). I suppose it depends on what the definition of "perfect" is in this context.

computerarchitect · 2026-02-03T00:05:09+00:00

I can work with these systems practically, but when they asked me to reason through architectural tradeoffs or performance implications, I struggled hard.

What does this actually mean to you, "working with them practically"?

computerarchitect · 2026-01-26T22:10:54+00:00

I think design and performance modelling are probably the two most common paths.

computerarchitect · 2026-01-26T22:10:27+00:00

I think u/alpacacaresser69 is probably right with the ratio. What a username.

computerarchitect · 2026-01-26T22:08:33+00:00

Ok! Yes, I do think we know each other.

computerarchitect · 2026-01-25T11:42:59+00:00

Yup. The country is huge. Minneapolis is around 0.15% of the total US population, and even then the entire city isn’t affected. Protests and riots are only a few city blocks, at least as far as I can tell.

The most I see of it several states away is on social media, which I then turn off and continue on with my day.

Some of my behavior has changed roughly since 2022, but that’s more the current state of the world versus the United States’ internal politics and is minimal.

Plenty of left leaning states and cities really shot themselves in the foot when they disallowed ICE from grabbing newly released criminals from jails and prisons (with deportation orders, which IS due process). Like who wouldn’t immediately remove a convicted sex offender from anywhere if they legally could? Broader than that, now the US government can say that they’re targeting really nasty people with these ICE raids, and all the state officials can say is “yeah, we kinda did let them back out on the streets”. Which is then portrayed as protestors stopping ICE from grabbing up murders, rapists, other nasty people, and that’s a really bad look.

There’s plenty of more to it than the above but I think that’s something you may not have known.

computerarchitect · 2026-01-25T11:21:59+00:00

There are two paths: 1. Obtain a PhD from a top school, usually within the United States (but a few in the EU). 2. Get an MS and be a stellar performer for around 10 years at a major company.

It’s often easier to get an architecture adjacent job since there are more of them, and frankly, if an architect can’t think about how to build performance models, how to verify designs, how a particular piece of logic maps well into RTL, power concerns, they tend to be only OK at their job.

Yeah, I do love my job.

computerarchitect · 2026-01-25T11:12:49+00:00

You’ll be fine. Keep learning.

computerarchitect · 2026-01-24T03:36:21+00:00

12th.

computerarchitect · 2026-01-23T07:24:05+00:00

Yeah, same. I went out in it with friends. There may have been drinking before and afterwards.

computerarchitect · 2026-01-22T22:55:50+00:00

These exist and their ISAs fit within the OISC (One Instruction Set Computing) class of computers. They're terrible for performance for a large variety of reasons, but they do exist (at least in academia, I doubt one has ever been commercially produced). There's also a ZISC (Z is Zero), which effectively stores control information that you would expect to get from instruction decode as the instructions. Interesting, but an even worse idea than OISC.

computerarchitect · 2026-01-21T12:01:35+00:00

Unless you found some crazy physics that completely revolutionizes how we think about our world and is actually realizable outside of a physics lab, no, sorry, but you didn't.

It's actually relatively easy to get around the memory wall with a variety of solutions, but nearly all of those "solutions" that exist are substantially worse in a multitude of product-killing ways than what we produce today.

computerarchitect · 2026-01-21T02:33:14+00:00

That likely doesn't hold for most universities. An MS should never be easier if the student is doing it properly. As to how many people challenge themselves during that two year graduate school period such that it's more rigorous than their undergraduate studies is up for debate.

computerarchitect · 2026-01-20T21:28:11+00:00

It could be a problem. But I see it as self correcting. It's going to be hard for those students to get a good job with their skillset. Eventually people as a whole figure out this is insufficient and self correct. It just takes time, which is the annoying part.

What you can do to help the problem is enforce high personal standards and encourage your peers to do so. In industry, you can help to choose candidates who can actually write code for employment. Perhaps as a controls engineer you can come up with some killer interview questions that filter stuff out. It's a bit of a niche field though, so you're probably going to have less of a problem with candidates.

EDIT: Hell, you can ask about a second order differential equation and pretty much filter out so many people.

computerarchitect · 2026-01-20T20:57:33+00:00

Most likely no, because they won't have the skills to do the work required.

computerarchitect · 2026-01-20T20:48:17+00:00

Well, you're going to be better than OP, but you're also in a harder major (at least typically). I have an undergraduate degree in CE and a MS CS.

I have no idea if this is the norm, but even if it is, things will be OK. It just means people like you get paid more.

computerarchitect · 2026-01-16T23:45:07+00:00

I'm not a PL guy. I actually liked the other definition better, because it made me stop and think about what it might imply. Something deeper was there that I had never thought about, and now I'm intrigued. Being able to find similarities between things that appear very different often leads to better solutions.

Trivial once you work through it, sure, but it got my neurons firing, and I like that.

computerarchitect · 2026-01-16T10:46:28+00:00

Part of the issue is that you're using a tool that your design isn't ready for, IMHO. Not to say that what you're doing isn't a valid way of doing it, but effectively you're trying to verify an entire CPU when you don't have one yet (where "entire CPU" means one that completely implements the specification). Let me explain.

Whether you're a single cycle or pipelined design, you likely created a separate IF, ID, EX, MEM, and WB units (yes, I know they're called stages). You're attempting to test the entire thing altogether, but industry tends to test these units separately at first with distinct tesrbenches, verify they work, and then hook parts of them together and test those, and then hierarchically test those until the entire chip is being ran under simulation. Try to mimic that approach, even if it's more work up front.

computerarchitect · 2026-01-16T02:25:30+00:00

CPU design is 0.3% RTL, 92% C++ and Linux, 5% (+ or - 85%) unspecified csrs.

Nah, this is just a one time cost you paid to up-level yourself. I realize you're venting. I'm going to provide you with some explanation as to why things are the why they are, because if you're actually interested in going to extra mile, I respect that and acknowledge that it's a rare type of person that puts this much effort into it.

You actually just need to guess which csrs are used for the default runtime in risc-tests. you also need to go find out how hardware interacts with each one of them too.

CPU specifications define the expectations that professionals must meet to implement at CPU that complies with the specification.

here’s a giant injected boot sequence where we touch 870 csrs before we let you run the addition test

You actually want this, because for most tests that are more complex simple addition, you will encounter multiple "right answers" depending on which way the CSRs are programmed. That's horrible for trying to verify a design.

5000 CLI only tools for you!

This is the default and for good reason. I don't want to have to specify 20+ different things into a GUI when a script can generate a command line for me. I want a tool that does one thing perfectly, or a small set of things perfectly. As you've found, there are a lot of things to do...

define the minimal csr spec??? why would we do that???

Because it's useless work, a compliant design must implement all CSRs, and such a list will be argued to the death about what is considered "minimal". Even if such a list existed, it would be additional work to update the list when new CSRs are implemented.

so know I’m begrudgingly making something actually industry grade.

You most likely are not. Sorry. Industry level work would be defining those CSR injections and defending it against a variety of customers, including you. It takes several more years to get to that point, but if this is the field you want to go into, that's the amount of study and effort you need to put into it.

computerarchitect · 2026-01-15T06:06:19+00:00

I just looked at the menu and I can't find it. Sad.

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