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There must be a simulation for this kind of architectures to see what is the best combination of size and components while making it practical! I wonder if anyo

There must be a simulation for this kind of architectures to see what is the best combination of size and components while making it practical! I wonder if anyone knows something like that? A tool to minmax these choices and estimate if this can be done with resources they have got.

willis936 7y ago
I’m pretty sure they roll their own. I would be surprised if simulation tools were not the most well guarded secrets of these companies.
chrisseaton 7y ago
They have many levels of simulations for their processor designs yes but they’re proprietary.
Symmetry 7y ago
Oh yes. That's been the dominant approach at least since Computer Architecture: A Quantitative Approach came out in '89. The search space is pretty complicated, though, given the physical interactions as well as the logical ones.
- sroussey 7y ago
  Sounds like a lot of parameters for some ML setup
repolfx 7y ago
Yeah but they're often trying to predict where the software industry will go years in advance. You can see that in the disagreements between AMD and Intel on AVX-512: there's a chicken and egg situation where it's not always clear what's right to optimise for, as it depends on changing workloads and software platforms. For instance the big chip companies were caught out by the need for low precision maths for AI inferencing. That all came out of Google.
ajross 7y ago
Tools like that are a core part of the design process. You write that software along with the choice of parametrization of the design. It's not an off the shelf thing. But yes, that's how it works. It's also important to note that decisions like this are hugely workload-specific. There's no single best processor for all applications. In extreme examples: almost every transistor on a vector SIMD unit is wasted when trying to optimize for a client Javascript benchmark; streaming symmetric encryption gets no benefit from L3 cache (which is like half the chip these days!); etc...
- mmrezaie 7y ago
  Do people like Jim Keller are the experts in finding the right balance? Is that why he and his team are so important?
- zazagura 7y ago
  Maybe the time has come for applications specific CPU variations? One optimized for node.js tasks, one for databases, ...
  - tempguy9999 7y ago
    > one for databases as a DB guy, there's no 'one task' for DBs . The only thing I can think that is nearly characteristic of DBs I've worked on is that they're IO bound. That's possibly true of most things except Floating point and graphics.
    - snaky 7y ago
      While that's true, you can achieve impressive results offloading particular parts of particular DBMS code to the specialized CPUs, https://www.ibm.com/support/knowledgecenter/en/SSEPEK_11.0.0/perf/src/tpc/db2z_ibmziip.html https://www.ibm.com/support/knowledgecenter/en/SSEPEK_11.0.0...
  - pjc50 7y ago
    ARM got a Javascript oriented instruction: http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dui0801g/hko1477562192868.html http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.... At least two different tasks, audio and graphics, have special application specific processors. Networking and crypto are also often offloaded.
brosenlof 7y ago
http://gem5.org http://gem5.org
positr0n 7y ago
http://gem5.org/Main_Page http://gem5.org/Main_Page Is an open source CPU simulator. I used it in undergrad to run benchmarks with different cache sizes and cache coherence strategies to see which were more effective. I'm sure Intel and AMD have much more advanced simulation tools though. Most likely multiple, or at least multiple levels of granularity (so you could do stuff like, simulate these potential branch predictor designs at a gate level, and then turn around and simulate the entire CPU at a higher level of abstraction.)
deepnotderp 7y ago
So yes, plenty of simulators exist, many internal ones as well as gem5* but automated search space exploration, say like with mcmc, isn't in widespread use yet iirc, although plenty of academic papers have explored the topic. *which I swear every company has their own version of

willis936 7y ago

I’m pretty sure they roll their own. I would be surprised if simulation tools were not the most well guarded secrets of these companies.

chrisseaton 7y ago

They have many levels of simulations for their processor designs yes but they’re proprietary.

Symmetry 7y ago

Oh yes. That's been the dominant approach at least since Computer Architecture: A Quantitative Approach came out in '89. The search space is pretty complicated, though, given the physical interactions as well as the logical ones.

sroussey 7y ago
Sounds like a lot of parameters for some ML setup

repolfx 7y ago

Yeah but they're often trying to predict where the software industry will go years in advance. You can see that in the disagreements between AMD and Intel on AVX-512: there's a chicken and egg situation where it's not always clear what's right to optimise for, as it depends on changing workloads and software platforms. For instance the big chip companies were caught out by the need for low precision maths for AI inferencing. That all came out of Google.

ajross 7y ago

Tools like that are a core part of the design process. You write that software along with the choice of parametrization of the design. It's not an off the shelf thing. But yes, that's how it works. It's also important to note that decisions like this are hugely workload-specific. There's no single best processor for all applications. In extreme examples: almost every transistor on a vector SIMD unit is wasted when trying to optimize for a client Javascript benchmark; streaming symmetric encryption gets no benefit from L3 cache (which is like half the chip these days!); etc...

mmrezaie 7y ago
Do people like Jim Keller are the experts in finding the right balance? Is that why he and his team are so important?
zazagura 7y ago
Maybe the time has come for applications specific CPU variations? One optimized for node.js tasks, one for databases, ...
- tempguy9999 7y ago
  > one for databases as a DB guy, there's no 'one task' for DBs . The only thing I can think that is nearly characteristic of DBs I've worked on is that they're IO bound. That's possibly true of most things except Floating point and graphics.
  - snaky 7y ago
    While that's true, you can achieve impressive results offloading particular parts of particular DBMS code to the specialized CPUs, https://www.ibm.com/support/knowledgecenter/en/SSEPEK_11.0.0/perf/src/tpc/db2z_ibmziip.html https://www.ibm.com/support/knowledgecenter/en/SSEPEK_11.0.0...
- pjc50 7y ago
  ARM got a Javascript oriented instruction: http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dui0801g/hko1477562192868.html http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.... At least two different tasks, audio and graphics, have special application specific processors. Networking and crypto are also often offloaded.

brosenlof 7y ago

http://gem5.org http://gem5.org

positr0n 7y ago

http://gem5.org/Main_Page http://gem5.org/Main_Page Is an open source CPU simulator. I used it in undergrad to run benchmarks with different cache sizes and cache coherence strategies to see which were more effective. I'm sure Intel and AMD have much more advanced simulation tools though. Most likely multiple, or at least multiple levels of granularity (so you could do stuff like, simulate these potential branch predictor designs at a gate level, and then turn around and simulate the entire CPU at a higher level of abstraction.)

deepnotderp 7y ago

So yes, plenty of simulators exist, many internal ones as well as gem5* but automated search space exploration, say like with mcmc, isn't in widespread use yet iirc, although plenty of academic papers have explored the topic. *which I swear every company has their own version of