Jeremy Chase [jeremych...@gmail.com] wrote: > This is my not-so-technical understanding. > > OpenBSD's current SMP status: > - The kernel uses a single lock for shared data. My understanding is > that this means that the kernel itself doesn't benefit from SMP as > much as it could otherwise, but it does use multiple cores. (I > believe, but would like confirmation from someone who knows)
Which isn't "symmetric" at all. Having said that, I suspect most people don't get much benefit today from SMP outside of heavy server applications.... > - Userland processes can run on as many cores as are supported. So if > you have multiple processes that are using a lot of CPU time, they > will be split across all cores. > - However all threads in a multi-threaded process will run on one > core. For example Mysql will only use a single core, even though it is > multi-threaded. > The threaded issue is actively being worked on with the development of the rthreads library and related kernel changes to accommodate rthreads. It turned out to be a deep hole, but it is likely to be working long before the kernel itself can use multiple processors > Bottom line, SMP is very well supported. People blow the BKL thing out > of proportion. I think people have looked at using multiple cores for offloading crypto, pf, various parts of the kernel, but make no mistake, the kernel is totally limited to one core. But, yeah, if you want to maximize your 48 core AMD box in a data center and you don't see make -j48 as a practical application, OpenBSD may not be "there" yet for you. I don't have anything with more than 4 cores, so it was never really a concern for me :)
