2016-07-06 18:44 GMT+08:00 Paolo Bonzini <pbonzini@xxxxxxxxxx>: > > > On 06/07/2016 08:52, Peter Zijlstra wrote: >> On Tue, Jun 28, 2016 at 10:43:07AM -0400, Pan Xinhui wrote: >>> change fomr v1: >>> a simplier definition of default vcpu_is_preempted >>> skip mahcine type check on ppc, and add config. remove dedicated macro. >>> add one patch to drop overload of rwsem_spin_on_owner and mutex_spin_on_owner. >>> add more comments >>> thanks boqun and Peter's suggestion. >>> >>> This patch set aims to fix lock holder preemption issues. >>> >>> test-case: >>> perf record -a perf bench sched messaging -g 400 -p && perf report >>> >>> 18.09% sched-messaging [kernel.vmlinux] [k] osq_lock >>> 12.28% sched-messaging [kernel.vmlinux] [k] rwsem_spin_on_owner >>> 5.27% sched-messaging [kernel.vmlinux] [k] mutex_unlock >>> 3.89% sched-messaging [kernel.vmlinux] [k] wait_consider_task >>> 3.64% sched-messaging [kernel.vmlinux] [k] _raw_write_lock_irq >>> 3.41% sched-messaging [kernel.vmlinux] [k] mutex_spin_on_owner.is >>> 2.49% sched-messaging [kernel.vmlinux] [k] system_call >>> >>> We introduce interface bool vcpu_is_preempted(int cpu) and use it in some spin >>> loops of osq_lock, rwsem_spin_on_owner and mutex_spin_on_owner. >>> These spin_on_onwer variant also cause rcu stall before we apply this patch set >>> >> >> Paolo, could you help out with an (x86) KVM interface for this? > > If it's just for spin loops, you can check if the version field in the > steal time structure has changed. Steal time will not be updated until ahead of next vmentry except wrmsr MSR_KVM_STEAL_TIME. So it can't represent it is preempted currently, right? Regards, Wanpeng Li -- 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
