From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751938AbaHSUhn (ORCPT ); Tue, 19 Aug 2014 16:37:43 -0400 Received: from mx1.redhat.com ([209.132.183.28]:62345 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751824AbaHSUhk (ORCPT ); Tue, 19 Aug 2014 16:37:40 -0400 From: =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= To: kvm@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Paolo Bonzini , Gleb Natapov , Raghavendra KT , Vinod Chegu , Hui-Zhi Subject: [PATCH 4/9] KVM: VMX: dynamise PLE window Date: Tue, 19 Aug 2014 22:35:31 +0200 Message-Id: <1408480536-8240-5-git-send-email-rkrcmar@redhat.com> In-Reply-To: <1408480536-8240-1-git-send-email-rkrcmar@redhat.com> References: <1408480536-8240-1-git-send-email-rkrcmar@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Window is increased on every PLE exit and decreased on every sched_in. The idea is that we don't want to PLE exit if there is no preemption going on. We do this with sched_in() because it does not hold rq lock. There are two new kernel parameters for changing the window: ple_window_grow and ple_window_shrink ple_window_grow affects the window on PLE exit and ple_window_shrink does it on sched_in; depending on their value, the window is modifier like this: (ple_window is kvm_intel's global) ple_window_shrink/ | ple_window_grow | PLE exit | sched_in -------------------+--------------------+--------------------- < 1 | = ple_window | = ple_window < ple_window | *= ple_window_grow | /= ple_window_shrink otherwise | += ple_window_grow | -= ple_window_shrink Signed-off-by: Radim Krčmář --- arch/x86/kvm/vmx.c | 52 ++++++++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 50 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index eaa5574..66259fd 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -125,14 +125,25 @@ module_param(nested, bool, S_IRUGO); * Time is measured based on a counter that runs at the same rate as the TSC, * refer SDM volume 3b section 21.6.13 & 22.1.3. */ -#define KVM_VMX_DEFAULT_PLE_GAP 128 -#define KVM_VMX_DEFAULT_PLE_WINDOW 4096 +#define KVM_VMX_DEFAULT_PLE_GAP 128 +#define KVM_VMX_DEFAULT_PLE_WINDOW 4096 +#define KVM_VMX_DEFAULT_PLE_WINDOW_GROW 2 +#define KVM_VMX_DEFAULT_PLE_WINDOW_SHRINK 0 + static int ple_gap = KVM_VMX_DEFAULT_PLE_GAP; module_param(ple_gap, int, S_IRUGO); static int ple_window = KVM_VMX_DEFAULT_PLE_WINDOW; module_param(ple_window, int, S_IRUGO); +/* Default doubles per-vcpu window every exit. */ +static int ple_window_grow = KVM_VMX_DEFAULT_PLE_WINDOW_GROW; +module_param(ple_window_grow, int, S_IRUGO); + +/* Default resets per-vcpu window every exit to ple_window. */ +static int ple_window_shrink = KVM_VMX_DEFAULT_PLE_WINDOW_SHRINK; +module_param(ple_window_shrink, int, S_IRUGO); + extern const ulong vmx_return; #define NR_AUTOLOAD_MSRS 8 @@ -5680,12 +5691,47 @@ out: return ret; } +static void grow_ple_window(struct kvm_vcpu *vcpu) +{ + struct vcpu_vmx *vmx = to_vmx(vcpu); + int old = vmx->ple_window; + int new; + + if (ple_window_grow < 1) + new = ple_window; + else if (ple_window_grow < ple_window) + new = old * ple_window_grow; + else + new = old + ple_window_grow; + + vmx->ple_window = new; +} + +static void shrink_ple_window(struct kvm_vcpu *vcpu) +{ + struct vcpu_vmx *vmx = to_vmx(vcpu); + int old = vmx->ple_window; + int new; + + if (ple_window_shrink < 1) + new = ple_window; + else if (ple_window_shrink < ple_window) + new = old / ple_window_shrink; + else + new = old - ple_window_shrink; + + vmx->ple_window = new; +} + /* * Indicate a busy-waiting vcpu in spinlock. We do not enable the PAUSE * exiting, so only get here on cpu with PAUSE-Loop-Exiting. */ static int handle_pause(struct kvm_vcpu *vcpu) { + if (ple_gap) + grow_ple_window(vcpu); + skip_emulated_instruction(vcpu); kvm_vcpu_on_spin(vcpu); @@ -8855,6 +8901,8 @@ static int vmx_check_intercept(struct kvm_vcpu *vcpu, void vmx_sched_in(struct kvm_vcpu *vcpu, int cpu) { + if (ple_gap) + shrink_ple_window(vcpu); } static struct kvm_x86_ops vmx_x86_ops = { -- 2.0.4