4 ms·

You can get a phi for $100 now, live a little. :)

by sitkack 6y ago

rbanffy 6y ago
I don't want the PCI board. I want a Knights Mill workstation motherboard. Those aren't easy to come by ;-)
- sitkack 6y ago
  Oh yeah, I am with you, I tried to map out what it would take to acquire. Sometimes the parts come up, but the likelihood you could get everything integrated properly and not have a pile of junk is pretty low. Then you have to find a mis-labeled workstation come up, where they just say HP bla-bla and not that is Phi. At least a grand, maybe 2 for crazy old hardware. You could go for a SparcT3, they are fairly cheap but not the massive sea of cores that Knights Mill is. https://www.ebay.com/itm/Intel-HJ8068303823700-SR3VD-Xeon-Phi-Processor-7295-16GB-1-5-GHz-72-Core-NEW/383701862969?hash=item595669ca39:g:SUcAAOSw9hZfTohe https://www.ebay.com/itm/Intel-HJ8068303823700-SR3VD-Xeon-Ph... Who is buying these? The vendor to show a sale? Is this just for money laundering? I haven't disassembled a Xeon Phi PCIe board, but I wouldn't be surprised if it literally isn't just this same chip in a low profile socket.
  - rbanffy 6y ago
    I think the PCI versions need the host to provide them all the IO services. IIRC, the host loads the OS image and then boots the Phi. OTOH, the early PCIe Phis had SMT4, so the thread count was higher than the latest versions. But... they were Cell PPU-like "threads" in that giving each core a single thread to work would result in overall 25% core utilization - useful if adding more threads results in more L2 cache misses. In that, the latest Phis are much nicer - the individual cores, while not doing SMT4 (or 2), are much better than the first-gen ones. I don't remember any SPARC T3 workstations too. Would have been smart to seed developers with them since before the first Niagara to encourage development for high thread counts, but Sun's management at the time wasn't known for their business acumen.
    - sitkack 6y ago
      I am just saying a T3 server is much more attainable than a Knights Landing workstation. Friend of mine is trying to get an Itanium workstation, expensive and difficult. I think simulators are probably way more appropriate now even though hard-hardware somehow makes things feel real. Every computation is a simulation, why not run the simulator on a simulation engine? https://fires.im/ https://fires.im/
pdimitar 6y ago
Question is, is it easy to program and use it in Linux? Last I checked some years ago, I think the tooling was proprietary?
- rbanffy 6y ago
  If you want to extract every bit of advertised performance, you'd probably be better off with Intel's proprietary compilers. If you can accept a little less, it runs fine with clang and gcc. It just looks like a lot of x86 cores with AVX512.

You can get a phi for $100 now, live a little. :)

rbanffy 6y ago

I don't want the PCI board. I want a Knights Mill workstation motherboard. Those aren't easy to come by ;-)

sitkack 6y ago
Oh yeah, I am with you, I tried to map out what it would take to acquire. Sometimes the parts come up, but the likelihood you could get everything integrated properly and not have a pile of junk is pretty low. Then you have to find a mis-labeled workstation come up, where they just say HP bla-bla and not that is Phi. At least a grand, maybe 2 for crazy old hardware. You could go for a SparcT3, they are fairly cheap but not the massive sea of cores that Knights Mill is. https://www.ebay.com/itm/Intel-HJ8068303823700-SR3VD-Xeon-Phi-Processor-7295-16GB-1-5-GHz-72-Core-NEW/383701862969?hash=item595669ca39:g:SUcAAOSw9hZfTohe https://www.ebay.com/itm/Intel-HJ8068303823700-SR3VD-Xeon-Ph... Who is buying these? The vendor to show a sale? Is this just for money laundering? I haven't disassembled a Xeon Phi PCIe board, but I wouldn't be surprised if it literally isn't just this same chip in a low profile socket.
- rbanffy 6y ago
  I think the PCI versions need the host to provide them all the IO services. IIRC, the host loads the OS image and then boots the Phi. OTOH, the early PCIe Phis had SMT4, so the thread count was higher than the latest versions. But... they were Cell PPU-like "threads" in that giving each core a single thread to work would result in overall 25% core utilization - useful if adding more threads results in more L2 cache misses. In that, the latest Phis are much nicer - the individual cores, while not doing SMT4 (or 2), are much better than the first-gen ones. I don't remember any SPARC T3 workstations too. Would have been smart to seed developers with them since before the first Niagara to encourage development for high thread counts, but Sun's management at the time wasn't known for their business acumen.
  - sitkack 6y ago
    I am just saying a T3 server is much more attainable than a Knights Landing workstation. Friend of mine is trying to get an Itanium workstation, expensive and difficult. I think simulators are probably way more appropriate now even though hard-hardware somehow makes things feel real. Every computation is a simulation, why not run the simulator on a simulation engine? https://fires.im/ https://fires.im/

pdimitar 6y ago

Question is, is it easy to program and use it in Linux? Last I checked some years ago, I think the tooling was proprietary?

rbanffy 6y ago
If you want to extract every bit of advertised performance, you'd probably be better off with Intel's proprietary compilers. If you can accept a little less, it runs fine with clang and gcc. It just looks like a lot of x86 cores with AVX512.