On Sat, Jul 11, 2009 at 02:52:43PM -0500, Andres Salazar wrote: > On Sat, Jul 11, 2009 at 1:54 AM, Jan-Erik Skata <jesk...@gmail.com> wrote > > > > Yes, you should use the SMP kernel on multicore CPUs aswell. I have usually > > just moved /bsd.mp onto /bsd and rebooted. > > Otherwise only one CPU and/or core will be used. > > Ok, however since this is Symmetric MultiProcessing then I wouldnt benefit > from running a mysql server because this is a single thread and it would > still only use one core, right? > > Does OpenBSD support asymmetrical processing ?
You have your terminology confused: the "symmetric" in SMP refers to the identical treatment of identical processors, not to any way of mapping threads to CPUs (CPU cores). See http://en.wikipedia.org/wiki/Asymmetric_multiprocessing for details. OpenBSD's current threading model is n:1, which means that scheduling is based on processes, not threads (i.e. only one thread of any given process can be on the CPU at a given time). See http://en.wikipedia.org/wiki/Thread_(computer_science)#Models. Some people are working on changing this, but they have been at it for a while and it is not production-ready yet. This does, indeed, mean that a multi-threaded process such as MySQL does not benefit from having multiple cores in the box, except to the extent that other work may be offloaded to other cores. I'll try to restrain myself from promoting PostgreSQL here... oops! Joachim
