On Mon, May 04, 2015 at 12:39:23PM -0700, Paul E. McKenney wrote: > But in non-preemptible RCU, we have PREEMPT=n, so there is no preempt > counter in production kernels. Even if there was, we have to sample this > on other CPUs, so the overhead of preempt_disable() and preempt_enable() > would be where kernel entry/exit is, so I expect that this would be a > net loss in overall performance.
We unconditionally have the preempt_count, its just not used much for PREEMPT_COUNT=n kernels. -- 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/
