On Wed, 2015-01-07 at 16:30 -0500, Yogesh Ahire wrote: > Hi All, > > I have a system with multiple CPU cores. I have multiple threads > assigned to particular CPU. Among these threads the main thread calls > sched_yield() if it has nothing to do, I am hoping that doing so will > give chance to other threads to run. But the strange behavior of > sched_yield() is , even if there are ready-to-runs tasks on this CPU > waiting for their turn, the task which calls sched_yield() is always > running ( get scheduled) and not giving chance to any other task to > run. It is consuming 100% of CPU. Is sched_yield() is broken on 2.6 > Kernel?
Nope, your expectation is likely busted. sched_yield() for a fair class task is merely a resched check in CFS. IFF there's a runnable task that's more deserving by the CFS definition thereof, it'll initiate a context switch, otherwise it's a non-free noop. For realtime class tasks, behavior is predictable, the scheduler WILL initiate a context switch IFF there is a runnable task of >= yielding tasks priority on the same CPU. If you depend on a context switch happening in any other circumstance, you're gonna be seriously disappointed. -Mike -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
