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Fri, 12 Jan 2007

SMP scalability in M-on-N threading model.


Actually it is simple.
Since only kernel can schedule thread (actually not even thread or process, but its own kernel's representation, so called kernel's virtual process) to run on specified CPU, M-on-N threading model should have several real threads (for example several current POSIX threads), its number should be equal to number of real CPUs, and then library layer will schedule execution of context of different real threads, each of which in turn can run on separate CPU.

So, userspace will create new real threads when pthread_create() is called until number of them is less than number of real CPUs, each real thread in turn is a context in the global tree of contexts, where fake context will be added with all subsequent pthread_create() calls, and userspace scheduler (backed by real threads) will pick up several contexts from the tree and execute them on the real CPUs.

Simple and looks really good.

/devel/threading :: Link / Comments ()