On 5/15/19 12:22 PM, David Hildenbrand wrote: > "KVM: s390: change default halt poll time to 50us > > Recent measurements indicate that using 50us results in a reduced CPU > consumption, while still providing the benefit of halt polling. Let's > use 50us instead." > > Acked-by: David Hildenbrand <david@xxxxxxxxxx> With that change: Acked-by: Janosch Frank <frankja@xxxxxxxxxxxxxxxxxx> > > > > On 15.05.19 10:23, Christian Borntraeger wrote: >> older performance measurements indicated that 50000 vs 80000 reduces cpu >> consumption while still providing the benefit of halt polling. We had >> this change in the IBM KVM product, but it got lost so it never went >> upstream. Recent re-measurement indicate that 50k is still better than >> 80k.> >> Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx> >> --- >> arch/s390/include/asm/kvm_host.h | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h >> index dbe254847e0d..cb63cc7bbf06 100644 >> --- a/arch/s390/include/asm/kvm_host.h >> +++ b/arch/s390/include/asm/kvm_host.h >> @@ -36,7 +36,7 @@ >> */ >> #define KVM_NR_IRQCHIPS 1 >> #define KVM_IRQCHIP_NUM_PINS 4096 >> -#define KVM_HALT_POLL_NS_DEFAULT 80000 >> +#define KVM_HALT_POLL_NS_DEFAULT 50000 >> >> /* s390-specific vcpu->requests bit members */ >> #define KVM_REQ_ENABLE_IBS KVM_ARCH_REQ(0) >> > >
