3 ms·

Have they worked out how to improve performance, or have they succeeded in spite of it? I run software that (thanks to poor design, IMO) manages to bottleneck

Have they worked out how to improve performance, or have they succeeded in spite of it? I run software that (thanks to poor design, IMO) manages to bottleneck context switching on Linux's monolithic kernel. I can't imagine this not being worse with more of the OS pushed out into userspace, though I'd love to be proven wrong!

lucian1900 12y ago
Kernels in the L4 [1] family are effectively designed to reduce the overhead of calls across process boundaries, to the extent that software is unlikely to behave any differently from a kernel like Linux. It can potentially be even better, since you can potentially get more direct access to whatever resource you're contending on. 1. http://en.wikipedia.org/wiki/L4_microkernel_family http://en.wikipedia.org/wiki/L4_microkernel_family
jckt 12y ago
According to this paper[1] about L4, it seems to be the former (that is, performance has genuinely improved). [1]http://www.nicta.com.au/pub?doc=6930 http://www.nicta.com.au/pub?doc=6930
Rusky 12y ago
L4 was a big push to improve microkernel performance. It's improved to the point that it only costs a few percent throughput, which means context switching itself on L4 is much faster than on Linux. The Mill CPU design doesn't have a user/kernel mode split, and it's also single-address-space (still with the same level of protection, just a different mechanism). Protection domain switching is done through portal calls, which are essentially shared library-like indirect calls with metadata for the CPU. Further, saving and restoring things like registers is done asynchronously. That should remove any remaining performance difference (and make monolithic designs faster too).
- SSLy 12y ago
  Where can I find more structured info about the mill cpu? Their www is basically empty.
  - Rusky 12y ago
    The vast majority of information available right now is in their videos: http://millcomputing.com/docs/ http://millcomputing.com/docs/ Their forum has some good responses from the team on follow up questions asked by the community as well.

lucian1900 12y ago

Kernels in the L4 [1] family are effectively designed to reduce the overhead of calls across process boundaries, to the extent that software is unlikely to behave any differently from a kernel like Linux. It can potentially be even better, since you can potentially get more direct access to whatever resource you're contending on. 1. http://en.wikipedia.org/wiki/L4_microkernel_family http://en.wikipedia.org/wiki/L4_microkernel_family

jckt 12y ago

According to this paper[1] about L4, it seems to be the former (that is, performance has genuinely improved). [1]http://www.nicta.com.au/pub?doc=6930 http://www.nicta.com.au/pub?doc=6930

Rusky 12y ago

L4 was a big push to improve microkernel performance. It's improved to the point that it only costs a few percent throughput, which means context switching itself on L4 is much faster than on Linux. The Mill CPU design doesn't have a user/kernel mode split, and it's also single-address-space (still with the same level of protection, just a different mechanism). Protection domain switching is done through portal calls, which are essentially shared library-like indirect calls with metadata for the CPU. Further, saving and restoring things like registers is done asynchronously. That should remove any remaining performance difference (and make monolithic designs faster too).

SSLy 12y ago
Where can I find more structured info about the mill cpu? Their www is basically empty.
- Rusky 12y ago
  The vast majority of information available right now is in their videos: http://millcomputing.com/docs/ http://millcomputing.com/docs/ Their forum has some good responses from the team on follow up questions asked by the community as well.