From: Paolo Bonzini Date: Tue, 18 Apr 2017 10:41:18 +0000 (+0200) Subject: KVM: x86: lower default for halt_poll_ns X-Git-Tag: v4.12-rc2~17^2~7 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=b401ee0b85a53e89739ff68a5b1a0667d664afc9;p=platform%2Fkernel%2Flinux-exynos.git KVM: x86: lower default for halt_poll_ns 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 Signed-off-by: Radim Krčmář --- diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 9c761fe..695605e 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -43,7 +43,7 @@ #define KVM_PRIVATE_MEM_SLOTS 3 #define KVM_MEM_SLOTS_NUM (KVM_USER_MEM_SLOTS + KVM_PRIVATE_MEM_SLOTS) -#define KVM_HALT_POLL_NS_DEFAULT 400000 +#define KVM_HALT_POLL_NS_DEFAULT 200000 #define KVM_IRQCHIP_NUM_PINS KVM_IOAPIC_NUM_PINS