From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755393AbYL1TRp (ORCPT ); Sun, 28 Dec 2008 14:17:45 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754796AbYL1TRg (ORCPT ); Sun, 28 Dec 2008 14:17:36 -0500 Received: from one.firstfloor.org ([213.235.205.2]:49330 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754169AbYL1TRf (ORCPT ); Sun, 28 Dec 2008 14:17:35 -0500 Date: Sun, 28 Dec 2008 20:30:46 +0100 From: Andi Kleen To: Avi Kivity Cc: Andi Kleen , Ingo Molnar , x86@kernel.org, linux-kernel , KVM list Subject: Re: [PATCH 0/3] Remove interrupt stack table usage from x86_64 kernel Message-ID: <20081228193046.GE496@one.firstfloor.org> References: <1230238726-17506-1-git-send-email-avi@redhat.com> <87vdt5vfxc.fsf@basil.nowhere.org> <4956A0B1.1060908@redhat.com> <20081227224029.GB496@one.firstfloor.org> <49573FE7.9090802@redhat.com> <20081228131605.GC496@one.firstfloor.org> <49578896.8030703@redhat.com> <20081228190840.GD496@one.firstfloor.org> <4957CE78.6030706@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4957CE78.6030706@redhat.com> User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > One fatal problem is enough -- I don't thing that patch can be made to > work. Pity since it did clean up some stuff. Not sure that was true anyways. > I would like however to speed up kvm. Here's a plan: > > 1. Add per-cpu IDT You don't need that, do you? Just two sets. > 2. When switching to the guest TR (and other state), switch off IST use > in the current IDT > 3. When switching away from the kvm task, restore the IST entries > > per-cpu IDT would cost around 4K per cpu. I propose to make it > kconfigurable, and have kvm select it. If anything please make it runtime switchable and disable it on Intel CPUs. -Andi -- ak@linux.intel.com