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I found this most surprising: > As you’ll recall from page two of your Building a Multithreaded Kernel textbook, when a high priority thread waits on a lock, i
by codys 10y ago
I found this most surprising:
> As you’ll recall from page two of your Building a Multithreaded Kernel textbook, when a high priority thread waits on a lock, it’s supposed to gift its priority to the lock holder to ensure progress is made. We (I) never quite got around to implementing that, and for several years it seemed we just might get away with it. The history of rthreads is pretty much maybe tomorrow, maybe not.
It sounds like OpenBSD has gotten away without having priority inheritance for most (all?) of it's history.
- kbenson 10y agoOpenBSD has been fairly niche for most of it's existence. They got SMP support in 2004, but that was 8 years after the project started. They just recently upgraded much of the network stack to use multiple processors more efficiently (or at all?) when processing packets, and that that's one of the core use cases for OpenBSD. In a perfect world, they would have done all this long ago. I'm pretty sure it's just a matter of not enough developers (or not enough developers of enough skill) to accomplish all the things they want to do.
- ben_bai 10y agoFrom my point of view it's the "measure before you optimize" mantra. Now with 10Gbit cards a single threaded pf and network stack could no longer keep up with the throughput of the NICs, so something had to be done