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I remember Linus playing around with a Xeon Phi CPU with a few hundred threads. The task manager was all percent signs. https://youtu.be/fBxtS9BpVWs?t=200 http

I remember Linus playing around with a Xeon Phi CPU with a few hundred threads. The task manager was all percent signs. https://youtu.be/fBxtS9BpVWs?t=200 https://youtu.be/fBxtS9BpVWs?t=200 Looks like Microsoft has already got 1000+ cores on Windows: https://techcommunity.microsoft.com/t5/Windows-Kernel-Internals/One-Windows-Kernel/ba-p/267142 https://techcommunity.microsoft.com/t5/Windows-Kernel-Intern... Can we get Bruce Dawson[0] one of those? I wonder how many more bugs he'll run into. [0] https://randomascii.wordpress.com/ https://randomascii.wordpress.com/

Macha 7y ago
I'm really curious about the machine it's running on. 896 physical cores is an odd number - 32 x 28, 16 x 56 or 8 x 112 are the likely combinations. The picture identifies it as a Xeon Platinum 8180 which is a 28C/56T CPU. Are there systems that support 32 Intel CPUs in one host? I thought quad socket was the practical limit these days.
- Dylan16807 7y ago
  Here's one, "HPE Superdome" https://h20195.www2.hpe.com/V2/getpdf.aspx/A00036491ENW.pdf https://h20195.www2.hpe.com/V2/getpdf.aspx/A00036491ENW.pdf See the diagram on page 6, they have a custom routing chip to link up 8 boards over UPI.
- paulmd 7y ago
  It says right there, Xeon Phi 7210. Knight's Landing supports 4-wide threading per core so you get 256 threads, which is exactly what it shows in task manager under "logical processors".
  - Macha 7y ago
    I was talking about the Microsoft article, not the LTT video, which are using different CPUs. The HP 32 socket chassis (8x4 socket boards) seems to be the answer.
masklinn 7y ago
> I remember Linus playing around with a Xeon Phi CPU with a few hundred threads. The task manager was all percent signs. The last Sun chips (Niagara / Ultrasparc Tx) also had pretty high count, IIRC they had 64 threads / socket, and were of course multi-socket systems. At 1.6GHz they were clocked pretty low for 2007 though.
Dylan16807 7y ago
> Can we get Bruce Dawson[0] one of those? I wonder how many more bugs he'll run into. Oh yeah, especially because core affinities in Windows get all wonky once you go above 64 threads.
- vardump 7y ago
  > Oh yeah, especially because core affinities in Windows get all wonky once you go above 64 threads. Can you elaborate? I haven't noticed any particular "wonkiness" happening?
  - Dylan16807 7y ago
    Thread affinities are tied to 64-bit numbers. So processor virtual cores are lumped into groups of at most 64. Threads can only be assigned to a single group at a time, and by default all threads in a process are locked to one group. https://bitsum.com/general/the-64-core-threshold-processor-groups-and-windows/ https://bitsum.com/general/the-64-core-threshold-processor-g... https://docs.microsoft.com/en-us/windows/win32/procthread/processor-groups https://docs.microsoft.com/en-us/windows/win32/procthread/pr...
    - vardump 7y ago
      Well, each thread being only able to be scheduled on some of 64 cores hasn't been a huge issue so far. Usually you want your threads to stay in the same NUMA region anyways because cross socket communication is expensive. Annoying if a processor group spans two NUMA regions leaving just a few processors to other side...
      - dijit 7y ago
        Huge issue for whom? Hypervisor developers are livid about this across all cloud providers. In practical terms the baseline of a windows OS is rather high, so if you have high density throughput of compute then you get more for your money. IE: You pay a license cost per CPU, and you pay at minimum 1physical CPU core and 1GiB of memory per Windows machine;
brucedawson 7y ago
If somebody gives me a ThreadRipper I promised to do some performance investigations. I keep meaning to update my fractal program (Fractal eXtreme) to support more than 64 threads and that would give me a good excuse (processor group support is needed). Anyone? Got a spare one lying around?
- nikhizzle 7y ago
  I would write to amd marketing. They will likely loan you a machine, or perhaps even give you one if you gave them tangible reasons.

Macha 7y ago

I'm really curious about the machine it's running on. 896 physical cores is an odd number - 32 x 28, 16 x 56 or 8 x 112 are the likely combinations. The picture identifies it as a Xeon Platinum 8180 which is a 28C/56T CPU. Are there systems that support 32 Intel CPUs in one host? I thought quad socket was the practical limit these days.

Dylan16807 7y ago
Here's one, "HPE Superdome" https://h20195.www2.hpe.com/V2/getpdf.aspx/A00036491ENW.pdf https://h20195.www2.hpe.com/V2/getpdf.aspx/A00036491ENW.pdf See the diagram on page 6, they have a custom routing chip to link up 8 boards over UPI.
paulmd 7y ago
It says right there, Xeon Phi 7210. Knight's Landing supports 4-wide threading per core so you get 256 threads, which is exactly what it shows in task manager under "logical processors".
- Macha 7y ago
  I was talking about the Microsoft article, not the LTT video, which are using different CPUs. The HP 32 socket chassis (8x4 socket boards) seems to be the answer.

masklinn 7y ago

> I remember Linus playing around with a Xeon Phi CPU with a few hundred threads. The task manager was all percent signs. The last Sun chips (Niagara / Ultrasparc Tx) also had pretty high count, IIRC they had 64 threads / socket, and were of course multi-socket systems. At 1.6GHz they were clocked pretty low for 2007 though.

Dylan16807 7y ago

> Can we get Bruce Dawson[0] one of those? I wonder how many more bugs he'll run into. Oh yeah, especially because core affinities in Windows get all wonky once you go above 64 threads.

vardump 7y ago
> Oh yeah, especially because core affinities in Windows get all wonky once you go above 64 threads. Can you elaborate? I haven't noticed any particular "wonkiness" happening?
- Dylan16807 7y ago
  Thread affinities are tied to 64-bit numbers. So processor virtual cores are lumped into groups of at most 64. Threads can only be assigned to a single group at a time, and by default all threads in a process are locked to one group. https://bitsum.com/general/the-64-core-threshold-processor-groups-and-windows/ https://bitsum.com/general/the-64-core-threshold-processor-g... https://docs.microsoft.com/en-us/windows/win32/procthread/processor-groups https://docs.microsoft.com/en-us/windows/win32/procthread/pr...
  - vardump 7y ago
    Well, each thread being only able to be scheduled on some of 64 cores hasn't been a huge issue so far. Usually you want your threads to stay in the same NUMA region anyways because cross socket communication is expensive. Annoying if a processor group spans two NUMA regions leaving just a few processors to other side...
    - dijit 7y ago
      Huge issue for whom? Hypervisor developers are livid about this across all cloud providers. In practical terms the baseline of a windows OS is rather high, so if you have high density throughput of compute then you get more for your money. IE: You pay a license cost per CPU, and you pay at minimum 1physical CPU core and 1GiB of memory per Windows machine;

brucedawson 7y ago

If somebody gives me a ThreadRipper I promised to do some performance investigations. I keep meaning to update my fractal program (Fractal eXtreme) to support more than 64 threads and that would give me a good excuse (processor group support is needed). Anyone? Got a spare one lying around?

nikhizzle 7y ago
I would write to amd marketing. They will likely loan you a machine, or perhaps even give you one if you gave them tangible reasons.