Re: [PATCH] x86/kvm: Don't use pvqspinlock code if only 1 vCPU

2018-07-19 Thread Waiman Long
On 07/18/2018 09:15 PM, Konrad Rzeszutek Wilk wrote: > On Tue, Jul 17, 2018 at 05:59:27PM -0400, Waiman Long wrote: >> On a VM with only 1 vCPU, the locking fast path will always be >> successful. In this case, there is no need to use the the PV qspinlock >> code which has higher overhead on the un

Re: [PATCH] x86/kvm: Don't use pvqspinlock code if only 1 vCPU

2018-07-18 Thread Konrad Rzeszutek Wilk
On Tue, Jul 17, 2018 at 05:59:27PM -0400, Waiman Long wrote: > On a VM with only 1 vCPU, the locking fast path will always be > successful. In this case, there is no need to use the the PV qspinlock > code which has higher overhead on the unlock side than the native > qspinlock code. Why not make

Re: [PATCH] x86/kvm: Don't use pvqspinlock code if only 1 vCPU

2018-07-18 Thread Paolo Bonzini
On 17/07/2018 23:59, Waiman Long wrote: > On a VM with only 1 vCPU, the locking fast path will always be > successful. In this case, there is no need to use the the PV qspinlock > code which has higher overhead on the unlock side than the native > qspinlock code. > > Signed-off-by: Waiman Long >

[PATCH] x86/kvm: Don't use pvqspinlock code if only 1 vCPU

2018-07-17 Thread Waiman Long
On a VM with only 1 vCPU, the locking fast path will always be successful. In this case, there is no need to use the the PV qspinlock code which has higher overhead on the unlock side than the native qspinlock code. Signed-off-by: Waiman Long --- arch/x86/kernel/kvm.c | 4 1 file changed, 4