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> --- 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 -- 2.9.3
