From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH 2/2] Add MSR Bitmap support in VMX Date: Thu, 02 Aug 2007 18:50:08 +0300 Message-ID: <46B1FD30.9040708@qumranet.com> References: <37E52D09333DE2469A03574C88DBF40F048ED2@pdsmsx414.ccr.corp.intel.com> <46B1D092.7070609@qumranet.com> <46B1E8D6.6010106@qumranet.com> <46B1EF29.9000200@qumranet.com> <13426df10708020830r5e716fb3p179f6937fb1f9412@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org, "He, Qing" To: ron minnich Return-path: In-Reply-To: <13426df10708020830r5e716fb3p179f6937fb1f9412-JsoAwUIsXosN+BqQ9rBEUg@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 ron minnich wrote: > On 8/2/07, Avi Kivity wrote: > >> Li, Xin B wrote: >> >>>> Did you see any performance improvements out of this? >>>> >>>> >>> Acturally we don't expect any obviously performance because MSR accesses >>> are not frequent. >>> >>> >> Well, why do this then? >> > > ah, see, you asked the question I was going to ask. OK, this can be > faster; but, are you sure you really care? > > Looking at the Linux context switch code, it can bang on MSR_FS_BASE and MSR_KERNEL_GS_BASE. A high context switch rate between threads (which use %gs or %fs) can show an improvement with this. Things like kbuild probably won't as they use single threaded processes. -- error compiling committee.c: too many arguments to function ------------------------------------------------------------------------- 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/