Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752415AbdFVLuG (ORCPT ); Thu, 22 Jun 2017 07:50:06 -0400 Received: from mail-oi0-f68.google.com ([209.85.218.68]:34936 "EHLO mail-oi0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751985AbdFVLuE (ORCPT ); Thu, 22 Jun 2017 07:50:04 -0400 MIME-Version: 1.0 In-Reply-To: <1498130534-26568-1-git-send-email-root@ip-172-31-39-62.us-west-2.compute.internal> References: <1498130534-26568-1-git-send-email-root@ip-172-31-39-62.us-west-2.compute.internal> From: Wanpeng Li Date: Thu, 22 Jun 2017 19:50:02 +0800 Message-ID: Subject: Re: [PATCH 0/2] x86/idle: add halt poll support To: root Cc: Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Paolo Bonzini , "the arch/x86 maintainers" , Jonathan Corbet , tony.luck@intel.com, Borislav Petkov , Peter Zijlstra , mchehab@kernel.org, Andrew Morton , krzk@kernel.org, jpoimboe@redhat.com, Andy Lutomirski , Christian Borntraeger , thgarnie@google.com, rgerst@gmail.com, minipli@googlemail.com, douly.fnst@cn.fujitsu.com, nicstange@gmail.com, Frederic Weisbecker , dvlasenk@redhat.com, Daniel Bristot de Oliveira , yamada.masahiro@socionext.com, mika.westerberg@linux.intel.com, Chen Yu , aaron.lu@intel.com, Steven Rostedt , me@kylehuey.com, Len Brown , Prarit Bhargava , hidehiro.kawai.ez@hitachi.com, fengtiantian@huawei.com, pmladek@suse.com, jeyu@redhat.com, Larry.Finger@lwfinger.net, zijun_hu@htc.com, luisbg@osg.samsung.com, johannes.berg@intel.com, niklas.soderlund+renesas@ragnatech.se, zlpnobody@gmail.com, adobriyan@gmail.com, fgao@48lvckh6395k16k5.yundunddos.com, ebiederm@xmission.com, subashab@codeaurora.org, arnd@arndb.de, Matt Fleming , Mel Gorman , "linux-kernel@vger.kernel.org" , linux-doc@vger.kernel.org, linux-edac@vger.kernel.org, kvm Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2054 Lines: 50 2017-06-22 19:22 GMT+08:00 root : > From: Yang Zhang > > Some latency-intensive workload will see obviously performance > drop when running inside VM. The main reason is that the overhead > is amplified when running inside VM. The most cost i have seen is > inside idle path. > This patch introduces a new mechanism to poll for a while before > entering idle state. If schedule is needed during poll, then we > don't need to goes through the heavy overhead path. > > Here is the data i get when running benchmark contextswitch > (https://github.com/tsuna/contextswitch) > before patch: > 2000000 process context switches in 4822613801ns (2411.3ns/ctxsw) > after patch: > 2000000 process context switches in 3584098241ns (1792.0ns/ctxsw) If you test this after disabling the adaptive halt-polling in kvm? What's the performance data of w/ this patchset and w/o the adaptive halt-polling in kvm, and w/o this patchset and w/ the adaptive halt-polling in kvm? In addition, both linux and windows guests can get benefit as we have already done this in kvm. Regards, Wanpeng Li > Yang Zhang (2): > x86/idle: add halt poll for halt idle > x86/idle: use dynamic halt poll > > Documentation/sysctl/kernel.txt | 24 ++++++++++ > arch/x86/include/asm/processor.h | 6 +++ > arch/x86/kernel/apic/apic.c | 6 +++ > arch/x86/kernel/apic/vector.c | 1 + > arch/x86/kernel/cpu/mcheck/mce_amd.c | 2 + > arch/x86/kernel/cpu/mcheck/therm_throt.c | 2 + > arch/x86/kernel/cpu/mcheck/threshold.c | 2 + > arch/x86/kernel/irq.c | 5 ++ > arch/x86/kernel/irq_work.c | 2 + > arch/x86/kernel/process.c | 80 ++++++++++++++++++++++++++++++++ > arch/x86/kernel/smp.c | 6 +++ > include/linux/kernel.h | 5 ++ > kernel/sched/idle.c | 3 ++ > kernel/sysctl.c | 23 +++++++++ > 14 files changed, 167 insertions(+) > > -- > 1.8.3.1 >