When running a KVM guest on a system with NOHZ_FULL enabled, and the KVM guest running with idle=poll mode, we still get wakeups of the rcuos/N threads. This problem has already been solved for user space by telling the RCU subsystem that the CPU is in an extended quiescent state while running user space code. This patch series extends that code a little bit to make it usable to track KVM guest space, too. I tested the code by booting a KVM guest with idle=poll, on a system with NOHZ_FULL enabled on most CPUs, and a VCPU thread bound to a CPU. In a 10 second interval, rcuos/N threads on other CPUs got woken up several times, while the rcuos thread on the CPU running the bound and alwasy running VCPU thread never got woken up once. Thanks to Christian Borntraeger and Paul McKenney for reviewing the first version of this patch series, and helping optimize patch 4/5. Thanks to Frederic Weisbecker for further enhancements. Apologies to Catalin and Will for not fixing up ARM. I am not familiar with ARM assembly, and not sure how to pass a constant argument to a function from assembly code on ARM :) -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
