similar to: Perf top show high osq_lock overhead

An over-committed guest with more vCPUs than pCPUs has a heavy overload in osq_lock(). This is because vCPU A hold the osq lock and yield out, vCPU B wait per_cpu node->locked to be set. IOW, vCPU B wait vCPU A to run and unlock the osq lock. Kernel has an interface bool vcpu_is_preempted(int cpu) to see if a vCPU is currently running or not. So break the spin loops on true condition. test

An over-committed guest with more vCPUs than pCPUs has a heavy overload in the two spin_on_owner. This blames on the lock holder preemption issue. Kernel has an interface bool vcpu_is_preempted(int cpu) to see if a vCPU is currently running or not. So break the spin loops on true condition. test-case: perf record -a perf bench sched messaging -g 400 -p && perf report before patch:

change from v2: no code change, fix typos, update some comments change from 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

change from v2: no code change, fix typos, update some comments change from 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

2016-07-06 20:28 GMT+08:00 Paolo Bonzini <pbonzini at redhat.com>: > > > On 06/07/2016 14:08, Wanpeng Li wrote: >> 2016-07-06 18:44 GMT+08:00 Paolo Bonzini <pbonzini at redhat.com>: >>> >>> >>> On 06/07/2016 08:52, Peter Zijlstra wrote: >>>> On Tue, Jun 28, 2016 at 10:43:07AM -0400, Pan Xinhui wrote: >>>>> change fomr

On 10/19/2016 12:20 PM, Pan Xinhui wrote: > change from v3: > add x86 vcpu preempted check patch If you want you could add the s390 patch that I provided for your last version. I also gave my Acked-by for all previous patches. > change from v2: > no code change, fix typos, update some comments > change from v1: > a simplier definition of default vcpu_is_preempted >

2016-07-06 18:44 GMT+08:00 Paolo Bonzini <pbonzini at redhat.com>: > > > 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. >>>

On 19/10/16 12:20, Pan Xinhui wrote: > change from v3: > add x86 vcpu preempted check patch > change from v2: > no code change, fix typos, update some comments > change from 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

On Fri, Oct 28, 2016 at 04:11:16AM -0400, Pan Xinhui wrote: > change from v5: > spilt x86/kvm patch into guest/host part. > introduce kvm_write_guest_offset_cached. > fix some typos. > rebase patch onto 4.9.2 > change from v4: > spilt x86 kvm vcpu preempted check into two patches. > add documentation patch. > add x86 vcpu preempted check patch under xen > add

On 06/07/2016 14:08, Wanpeng Li wrote: > 2016-07-06 18:44 GMT+08:00 Paolo Bonzini <pbonzini at redhat.com>: >> >> >> 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

On 06/07/2016 14:08, Wanpeng Li wrote: > 2016-07-06 18:44 GMT+08:00 Paolo Bonzini <pbonzini at redhat.com>: >> >> >> 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

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

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

change from v3: add x86 vcpu preempted check patch change from v2: no code change, fix typos, update some comments change from 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.

change from v3: add x86 vcpu preempted check patch change from v2: no code change, fix typos, update some comments change from 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.

On 07/06/2016 02:52 AM, 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

On 07/06/2016 02:52 AM, 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

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

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

v2: - fix compile issues if no CONFIG_SMP, Konrad Rzeszutek Wilk - move inc_irq_stat after irq_work_run These 2 patches fixed the "perf top" soft lockups under Xen reported by Steven at: https://lkml.org/lkml/2012/2/9/506 Both Steven and I tested it and "perf top" works well now. The soft lockup code path is: __irq_work_queue arch_irq_work_raise