From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH] KVM: VMX: Enable memory mappedTPR shadow(FlexPriority) Date: Tue, 30 Oct 2007 13:46:41 +0200 Message-ID: <472719A1.6070709@qumranet.com> References: <1193657732.4484.17.camel@izike-woof.qumranet.com> <10EA09EFD8728347A513008B6B0DA77A024CEC5E@pdsmsx411.ccr.corp.intel.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============1613848478==" Cc: kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org To: "Dong, Eddie" Return-path: In-Reply-To: <10EA09EFD8728347A513008B6B0DA77A024CEC5E-wq7ZOvIWXbNpB2pF5aRoyrfspsVTdybXVpNB7YpNyf8@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org Errors-To: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: kvm.vger.kernel.org --===============1613848478== Content-Type: text/plain; charset=GB2312 Content-Transfer-Encoding: 7bit Dong, Eddie wrote: >> >>> From: Sheng Yang >>> Date: Mon, 29 Oct 2007 09:40:42 +0800 >>> Subject: [PATCH] KVM: VMX: Enable memory mapped TPR >>> >> shadow(FlexPriority) >> >>> This patch based on CR8/TPR patch, and enable the TPR >>> shadow(FlexPriority) >>> for 32bit Windows. Since TPR is accessed very frequently by 32bit >>> Windows, >>> especially SMP guest, with FlexPriority enabled, we saw significant >>> performance gain. >>> >> patch look much better, and everything seems to be fine as i >> look at it. >> lets wait avi to review it >> >> > Ack too :-) > > Basically this patch will have same functionality/result with what Avi > did for optimizing Windows. Dynamic patch works on all HWs, but > may crash the guest if guest kernel has integrity check or patch > guard. This one avoid this issue, but require new HWs :-) > > I assume all comming processor will have this feature, some existing > processor also has this feature, so now we can have whole bunch of > solution: new HW will use HW features + any modern OSes; > old HWs will use dynamic patching with assumption no patch guard in guest > which is true so far. > Yes. FlexPriority will be both faster and safer for those who have it than my hack. It may turn out that patching can improve performance even with FlexPriority: we can patch the APIC EOI write to look if any interrupts are pending, and only exit if the EOI will result in a new interrupt being injected. But it is very possible that this will not be necessary if we can achieve good interrupt mitigation with virtio. -- Any sufficiently difficult bug is indistinguishable from a feature. --===============1613848478== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ --===============1613848478== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ kvm-devel mailing list kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org https://lists.sourceforge.net/lists/listinfo/kvm-devel --===============1613848478==--