On 18/04/2017 12:41, Paolo Bonzini wrote: > In some fio benchmarks, halt_poll_ns=400000 caused CPU utilization to > increase heavily even in cases where the performance improvement was > small. In particular, bandwidth divided by CPU usage was as much as > 60% lower. > > To some extent this is the expected effect of the patch, and the > additional CPU utilization is only visible when running the > benchmarks. However, halving the threshold also halves the extra > CPU utilization (from +30-130% to +20-70%) and has no negative > effect on performance. > > Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx> Ping? Paolo > --- > arch/x86/include/asm/kvm_host.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > index 74ef58c8ff53..68d4a33da392 100644 > --- a/arch/x86/include/asm/kvm_host.h > +++ b/arch/x86/include/asm/kvm_host.h > @@ -45,7 +45,7 @@ > > #define KVM_PIO_PAGE_OFFSET 1 > #define KVM_COALESCED_MMIO_PAGE_OFFSET 2 > -#define KVM_HALT_POLL_NS_DEFAULT 400000 > +#define KVM_HALT_POLL_NS_DEFAULT 200000 > > #define KVM_IRQCHIP_NUM_PINS KVM_IOAPIC_NUM_PINS > >
