This is a respin of a patch I posted a long while ago, this time with numbers that I hope to be convincing enough. The basic idea is that spinning on WFE in a guest is a waste of resource, and that we're better of running another vcpu instead. This specially shows when the system is oversubscribed. The guest vcpus can be seen spinning, waiting for a lock to be released while the lock holder is nowhere near a physical CPU. This patch series just enables WFE trapping on both ARM and arm64, and calls kvm_vcpu_on_spin(). This is enough to boost other vcpus, and dramatically reduce the overhead. Branch available at: git://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git kvm-arm64/wfe-trap Marc Zyngier (2): ARM: KVM: Yield CPU when vcpu executes a WFE arm64: KVM: Yield CPU when vcpu executes a WFE arch/arm/include/asm/kvm_arm.h | 4 +++- arch/arm/kvm/handle_exit.c | 6 +++++- arch/arm64/include/asm/kvm_arm.h | 8 ++++++-- arch/arm64/kvm/handle_exit.c | 18 +++++++++++++----- 4 files changed, 27 insertions(+), 9 deletions(-) -- 1.8.2.3 _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/cucslists/listinfo/kvmarm
