From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756498Ab2HHDx2 (ORCPT ); Tue, 7 Aug 2012 23:53:28 -0400 Received: from terminus.zytor.com ([198.137.202.10]:53711 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751370Ab2HHDxW (ORCPT ); Tue, 7 Aug 2012 23:53:22 -0400 Message-ID: <5021E2A2.8080606@zytor.com> Date: Tue, 07 Aug 2012 20:53:06 -0700 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:14.0) Gecko/20120717 Thunderbird/14.0 MIME-Version: 1.0 To: zhenzhong.duan@oracle.com CC: tglx@linutronix.de, mingo@redhat.com, x86@kernel.org, linux-kernel@vger.kernel.org, Konrad Rzeszutek Wilk , Feng Jin Subject: Re: [PATCH] Parallelize mtrr init between cpus References: <5020C3D7.2070407@oracle.com> <5021432F.2030907@zytor.com> <5021CA31.7000405@oracle.com> In-Reply-To: <5021CA31.7000405@oracle.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/07/2012 07:08 PM, zhenzhong.duan wrote: > > > 2012-08-08 00:32, H. Peter Anvin wrote: >> On 08/07/2012 12:29 AM, zhenzhong.duan wrote: >>> Current code serialize mtrr init with set_atomicity_lock. >>> Mtrr init is quite slow when we bootup on a hvm with large mem, vcpus >>> and pci passthroughed devices(eg. 24 vcpus + 90G mem). >>> It took about ~30 mins to bootup, after patch, it took ~2 min. >> When you're saying "HVM" do you mean "Xen HVM"? How does it behave on >> native hardware? >> >> -hpa > Yes, I mean Xen HVM. Bootup at same speed as before on baremetal. Then I would like to know why Xen HVM takes so infernally long. It isn't a good idea to make gratuitous changes in the main kernel to work around defects in Xen. -hpa -- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf.