anexanhume
Veteran
Simon Pilgrim commits plenty on his own, including AVX512.Those commits were done by AMD.
C) Sony developer Code Reviews optimizations for Zen 2.
Simon Pilgrim commits plenty on his own, including AVX512.Those commits were done by AMD.
C) Sony developer Code Reviews optimizations for Zen 2.
Simon Pilgrim commits plenty on his own, including AVX512.
The commit itself states that it's simply a clone of the Zen1 capabilities for now, so you could reasonably assume that any Zen1 commits prior were placeholders for Zen2 optimizations as well.We're talking about this Specific Rumor that is tied to this Specific Commit, that was done by an AMD employee.
As far as thIs rumor goes, it is Non Sequitur.
The commit itself states that it's simply a clone of the Zen1 capabilities for now, so you could reasonably assume that any Zen1 commits prior were placeholders for Zen2 optimizations as well.
The rumor is not predicated on the link. It was completely independent of that. It existed well before that was made public.None of which is evidence of PS5 being Zen2. Hence, this rumor is entirely Non Sequitur.
The rumor is not predicated on the link. It was completely independent of that. It existed well before that was made public.
Try not to get hung up on precedent. If you only accept ideas and concepts for which there is precedent, you automatically reject everything which is new.B) Sony’s lead developers work with LLVM and use it internally for their tools and have been working with it for a long time. I suppose we should see The PS3 processor in LLVM then ? I’m trying to explore precedent.
Once again, we were talking about the latest rumor that is linked to that latest commit.
There is no rumor. It’s not a questionable piece of information sourced from a journalist. It’s a hard fact in a public-facing repository. We’re debating over what conclusions to draw, not whether to believe the source.Once again, we were talking about the latest rumor that is linked to that latest commit.
You stated that Zen 2 was confirmed and cited the commit as evidence:There is no rumor. It’s not a questionable piece of information sourced from a journalist. It’s a hard fact in a public-facing repository. We’re debating over what conclusions to draw, not whether to believe the source.
The rumour is from you, that PS5's has Zen 2, as confirmed by an LLVM commit. Without concrete evidence, it's a rumour, and the evidence has not been explained as proof of your claim.Zen 2 confirmed for PS5.
https://reviews.llvm.org/D58343
But is it a concrete rumour?You stated that Zen 2 was confirmed and cited the commit as evidence:
The rumour is from you, that PS5's has Zen 2, as confirmed by an LLVM commit. Without concrete evidence, it's a rumour, and the evidence has not been explained as proof of your claim.
okay welp, I screwed that up. That really makes this commit to Znver2 pretty irrelevant on whether PS5 is going Zen2.Those commits were done by AMD.
C) Sony developer Code Reviews optimizations for Zen 2.
This is the basic patch introducing the next-generation AMD Zen CPU to the GCC compiler collection. At this stage it's just the basic implementation and carries over the same cost tables and scheduler data from Znver1. So it doesn't reveal any major breakthrough changes, but in digging through the code, it does confirm some new CPU instructions that will be supported by these next-gen Zen CPUs... On top of the Znver1 instructions, Zen 2 is adding:
- Cache Line Write Back (CLWB)
- Read Processor ID (RDPID)
- Write Back and Do Not Invalidate Cache (WBNOINVD)
That's it in terms of new instructions, at least what's enabled by these patches. It's possible there might be some other new instructions supported by Zen 2 that AMD doesn't want to reveal at this time, just like the scheduler cost tables haven't yet been tuned, etc. This patch is basically a starting point so the GCC 9.1 stable update due out in 2019 can at least handle -march=znver2 and that march=native targeting will also work for these next-gen AMD processors.
Agreed, I'm just exploring. Yea I would assume PS4 would have been precedent. Back in 2013 I'm not sure if we have access to those commits, but would we find something like Simon dropping commits that optimize for what became PS4 architecture, before PS4 was released?Try not to get hung up on precedent. If you only accept ideas and concepts for which there is precedent, you automatically reject everything which is new.
But the precedent is surely, PS4?
AVX512 commits are expressly called out as such. It’s not a stretch to think that Zen 2 could support AVX512 by double cycling its 256 bit ALUs, just as their current architectures do on 128-bit units for AVX2.Agreed, I'm just exploring. Yea I would assume PS4 would have been precedent. Back in 2013 I'm not sure if we have access to those commits, but would we find something like Simon dropping commits that optimize for what became PS4 architecture, before PS4 was released?
AVX512 discussion is interesting because I don't think AVX512 is even confirmed for Zen 2? Perhaps my GoogleFu is falling behind, but aside from some rumours, I don't see anything about confirmation of that instruction set.
AFAICS at this moment, Simon's optimizations are being used for Intel processors. I will loop back to my original theory that these commits support tool optimization (studios need more bang for buck for their hardware, video encoding etc) and not the console hardware.
Are we sure there isn't some sort of mixup on AVX with AVX512 in the code? As Jaguar supports AVX
You stated that Zen 2 was confirmed and cited the commit as evidence:
The rumour is from you, that PS5's has Zen 2, as confirmed by an LLVM commit. Without concrete evidence, it's a rumour, and the evidence has not been explained as proof of your claim.
especially since 0 people in this thread seem to contend that Sony isn’t using a Zen derivative.
Zen 1 doesn't have it. I'll be honest, not sure if that means they can just jump it with Zen 2. I guess this is a wait and see type of thing. If it was a new CPU architecture entirely I could see AVX512 as a definite.AVX512 commits are expressly called out as such. It’s not a stretch to think that Zen 2 could support AVX512 by double cycling its 256 bit ALUs, just as their current architectures do on 128-bit units for AVX2.
I'm the only one still left on this, and only because we found reference in a textbook about it. The only reason this point is worth discussing isn't because it's performance matters, but whether that has implications into next gen.Are we going to keep debating this even after it releases, a la the Xbox One X doesn’t use Jaguar discussion?
I have some reservations still. I think there are a lot of fantastic reasons to go Zen 2. At the heart of my reservation is mainly price. Followed closely secondly by backwards compatibility. You have to look at this from AMD's perspective. You have a processor that can finally compete with Intel. Are you really going to sell it at rock bottom prices and have all your fabs producing 120 Million APUs for nothing? There either is going to be good margins on this coming APU or it's not Zen. It's unlikely to be a chiplet either, so binning isn't a possibility.since 0 people in this thread seem to contend that Sony isn’t using a Zen derivative.
So here, Agner doesn't believe in 512-bit vector support coming soon for AMD, thus AVX512 is in question again.Let us compare the execution units of AMD's Ryzen with current Intel processors. AMD has four 128-bit units for floating point and vector operations. Two of these can do addition and two can do multiplication. Intel has two 256-bit units, both of which can do addition as well as multiplication. This means that floating point code with scalars or vectors of up to 128 bits will execute on the AMD processor at a maximum rate of four instructions per clock (two additions and two multiplications), while the Intel processor can do only two. With 256-bit vectors, AMD and Intel can both do two instructions per clock. Intel beats AMD on 256-bit fused multiply-and-add instructions, where AMD can do one while Intel can do two per clock. Intel is also better than AMD on 256-bit memory writes, where Intel has one 256-bit write port while the AMD processor has one 128-bit write port. We will soon see Intel processors with 512-bit vector support, while it might take a few more years before AMD supports 512-bit vectors. However, most of the software on the market lags several years behind the hardware. As long as the software uses only 128-bit vectors, we will see the performance of the Ryzen processor as quite competitive. The AMD can execute six micro-ops per clock while Intel can do only four. But there is a problem with doing so many operations per clock cycle. It is not possible to do two instructions simultaneously if the second instruction depends on the result of the first instruction, of course. The high throughput of the processor puts an increased burden on the programmer and the compiler to avoid long dependency chains. The maximum throughput can only be obtained if there are many independent instructions that can be executed simultaneously.
This is where simultaneous multithreading comes in. You can run two threads in the same CPU core (this is what Intel calls hyperthreading). Each thread will then get half of the resources. If the CPU core has a higher capacity than a single thread can utilize then it makes sense to run two threads in the same core. The gain in total performance that you get from running two threads per core is much higher in the Ryzen than in Intel processors because of the higher throughput of the AMD core (except for 256-bit vector code).
AMD has a different way of dealing with instruction set extensions than Intel. AMD keeps adding new instructions and remove them again if they fail to gain popularity, while Intel keeps supporting even the most obscure and useless undocumented instructions dating back to the first 8086. AMD introduced the FMA4 and XOP instruction set extensions with Bulldozer, and some not very useful extensions called TBM with Piledriver. Now they are dropping all these again. XOP and TBM are no longer supported in Ryzen. FMA4 is not officially supported on Ryzen, but I found that the FMA4 instructions actually work correctly on Ryzen, even though the CPUID instruction says that FMA4 is not supported.
AVX512 commits are expressly called out as such. It’s not a stretch to think that Zen 2 could support AVX512 by double cycling its 256 bit ALUs, just as their current architectures do on 128-bit units for AVX2.
It's not pedantry. You stated, absolute, that Zen2 was confirmed for PS5. The evidence presented for such an statement must be similarly absolute and undebatable. If you want to say, "does this point to Zen2 confirmation in PS5?" then you'll get a very different discussion. If you want to stick by your point that Zen2 is confirmed for PS5, link to an unquestionably clear leaked document or executive announcement. Everything else, even a DF confirmed insider rumour, is speculation, not confirmation.Since we’re venturing into pedantry here, what constitutes concrete evidence?
I think the only way that would happen is if they were willing to pull a Nintendo, and that might come down to cost/benefit to the company as a whole (not feeding some console war), and be pretty far out there with a number of additional factors aligning to make that decision.
Zen 1 doesn't have it. I'll be honest, not sure if that means they can just jump it with Zen 2. I guess this is a wait and see type of thing. If it was a new CPU architecture entirely I could see AVX512 as a definite.
I have some reservations still. I think there are a lot of fantastic reasons to go Zen 2. At the heart of my reservation is mainly price. Followed closely secondly by backwards compatibility. You have to look at this from AMD's perspective. You have a processor that can finally compete with Intel. Are you really going to sell it at rock bottom prices and have all your fabs producing 120 Million APUs for nothing? There either is going to be good margins on this coming APU or it's not Zen. It's unlikely to be a chiplet either, so binning isn't a possibility.
At the bottom barrel of PC parts I can find the following:
4 Core Ryzen 3 (120 CAD)
Mobo (109 CAD)
Memory (145)
GPU Radeon 580 (319)
Sitting at 693 dollars and haven't gotten into anything else yet like a disc drive, power, case, fans and storage.
And that's pretty bottom of the barrel. The idea we're going to get this 8 core Zen 2 + 11 TF of power at 499 CAD? hmmmm. I was way wrong before and learned my lesson with Scorpio thinking it was going to be Zen 1.
Going to quote a blog post from Agner: https://www.agner.org/optimize/blog/read.php?i=838
So here, Agner doesn't believe in 512-bit vector support coming soon for AMD, thus AVX512 is in question again.
It's not pedantry. You stated, absolute, that Zen2 was confirmed for PS5. The evidence presented for such an statement must be similarly absolute and undebatable. If you want to say, "does this point to Zen2 confirmation in PS5?" then you'll get a very different discussion. If you want to stick by your point that Zen2 is confirmed for PS5, link to an unquestionably clear leaked document or executive announcement. Everything else, even a DF confirmed insider rumour, is speculation, not confirmation.