4 ms·

There are fundamental reasons for OS threads being slow, mostly to do with processor design. Changing the silicon would be hundreds of times more expensive than

There are fundamental reasons for OS threads being slow, mostly to do with processor design. Changing the silicon would be hundreds of times more expensive than solving the problem in software in user mode. This is a billion-dollar solution to a hundred-billion dollar problem.

Animats 2y ago
There is a history of trying to support context switching in CPU hardware. That was a hot idea decades ago. Intel had call gates and some other stuff. Some of the RISC machines had hardware to spill all the registers to memory in background. Some early machines, from the days where CPUs were slower than memory, just had a context pointer in hardware. Change that and you're running a different thread. None of this helped all that much. Vanilla hardware won out. This is to some extent a consequence of C winning. C likes a single flat address space.
- harry8 2y ago
  > a consequence of C winning. C likes a single flat address space. Interesting. What other language did C beat? How was their address space handling different?
  - Animats 2y ago
    C allows casting to (void *). That implies all pointers are in the same address space. Segmented architectures, where that's not true, have mostly died out. Burroughs used to build segmented address space machines where an address was a path, something like programname/scopename/variablename[subscript]. IBM's System 38 had an "object" architecture. Both worked fine, but were not very C-compatible.
    - harry8 2y ago
      Thanks.
- yencabulator 2y ago
  One interesting angle is Mill (note, vaporware). Their "portal" calls between security boundaries are essentially the same as their EBB function calls. https://www.youtube.com/watch?v=XJasE5aOHSw https://www.youtube.com/watch?v=XJasE5aOHSw
  - jiggawatts 2y ago
    Mill is still vaporware. As far as I can tell, they’ve never made anything from silicon. Compare their progress to RISC-V, which started later and is now shipping in hundreds of products at volume.
    - yencabulator 2y ago
      Yeah, Mill hasn't been able to find funding to go beyond simulator+compiler+thoughts about FPGA. Compared to Mill, RISC-V is nearly identical to Arm and X86-64.

Animats 2y ago

There is a history of trying to support context switching in CPU hardware. That was a hot idea decades ago. Intel had call gates and some other stuff. Some of the RISC machines had hardware to spill all the registers to memory in background. Some early machines, from the days where CPUs were slower than memory, just had a context pointer in hardware. Change that and you're running a different thread. None of this helped all that much. Vanilla hardware won out. This is to some extent a consequence of C winning. C likes a single flat address space.

harry8 2y ago
> a consequence of C winning. C likes a single flat address space. Interesting. What other language did C beat? How was their address space handling different?
- Animats 2y ago
  C allows casting to (void *). That implies all pointers are in the same address space. Segmented architectures, where that's not true, have mostly died out. Burroughs used to build segmented address space machines where an address was a path, something like programname/scopename/variablename[subscript]. IBM's System 38 had an "object" architecture. Both worked fine, but were not very C-compatible.
  - harry8 2y ago
    Thanks.
yencabulator 2y ago
One interesting angle is Mill (note, vaporware). Their "portal" calls between security boundaries are essentially the same as their EBB function calls. https://www.youtube.com/watch?v=XJasE5aOHSw https://www.youtube.com/watch?v=XJasE5aOHSw
- jiggawatts 2y ago
  Mill is still vaporware. As far as I can tell, they’ve never made anything from silicon. Compare their progress to RISC-V, which started later and is now shipping in hundreds of products at volume.
  - yencabulator 2y ago
    Yeah, Mill hasn't been able to find funding to go beyond simulator+compiler+thoughts about FPGA. Compared to Mill, RISC-V is nearly identical to Arm and X86-64.