v2 -> v3: * copy&paste frenzy [v3 4/7] (split modify_ple_window) * commented update_ple_window_actual_max [v3 4/7] * renamed shrinker to modifier [v3 4/7] * removed an extraneous max(new, ple_window) [v3 4/7] (should have been in v2) * changed tracepoint argument type, printing and macro abstractions [v3 5/7] * renamed ple_t to ple_int [v3 6/7] (visible in modinfo) * intelligent updates of ple_window [v3 7/7] --- v1 -> v2: * squashed [v1 4/9] and [v1 5/9] (clamping) * dropped [v1 7/9] (CPP abstractions) * merged core of [v1 9/9] into [v1 4/9] (automatic maximum) * reworked kernel_param_ops: closer to pure int [v2 6/6] * introduced ple_window_actual_max & reworked clamping [v2 4/6] * added seqlock for parameter modifications [v2 6/6] --- PLE does not scale in its current form. When increasing VCPU count above 150, one can hit soft lockups because of runqueue lock contention. (Which says a lot about performance.) The main reason is that kvm_ple_loop cycles through all VCPUs. Replacing it with a scalable solution would be ideal, but it has already been well optimized for various workloads, so this series tries to alleviate one different major problem while minimizing a chance of regressions: we have too many useless PLE exits. Just increasing PLE window would help some cases, but it still spirals out of control. By increasing the window after every PLE exit, we can limit the amount of useless ones, so we don't reach the state where CPUs spend 99% of the time waiting for a lock. HP confirmed that this series prevents soft lockups and TSC sync errors on large guests. Radim Krčmář (7): KVM: add kvm_arch_sched_in KVM: x86: introduce sched_in to kvm_x86_ops KVM: VMX: make PLE window per-VCPU KVM: VMX: dynamise PLE window KVM: trace kvm_ple_window grow/shrink KVM: VMX: runtime knobs for dynamic PLE window KVM: VMX: optimize ple_window updates to VMCS arch/arm/kvm/arm.c | 4 ++ arch/mips/kvm/mips.c | 4 ++ arch/powerpc/kvm/powerpc.c | 4 ++ arch/s390/kvm/kvm-s390.c | 4 ++ arch/x86/include/asm/kvm_host.h | 2 + arch/x86/kvm/svm.c | 6 ++ arch/x86/kvm/trace.h | 30 ++++++++ arch/x86/kvm/vmx.c | 147 ++++++++++++++++++++++++++++++++++++++-- arch/x86/kvm/x86.c | 6 ++ include/linux/kvm_host.h | 2 + virt/kvm/kvm_main.c | 2 + 11 files changed, 207 insertions(+), 4 deletions(-) -- 2.1.0 -- 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
