From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joerg Roedel Subject: Re: [PATCH 4/9] Implement GIF, clgi and stgi v3 Date: Thu, 25 Sep 2008 23:27:49 +0200 Message-ID: <20080925212749.GN27426@8bytes.org> References: <1221658886-14109-1-git-send-email-agraf@suse.de> <1221658886-14109-2-git-send-email-agraf@suse.de> <1221658886-14109-3-git-send-email-agraf@suse.de> <1221658886-14109-4-git-send-email-agraf@suse.de> <1221658886-14109-5-git-send-email-agraf@suse.de> <20080925184759.GL27426@8bytes.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: kvm@vger.kernel.org, anthony@codemonkey.ws, avi@qumranet.com To: Alexander Graf Return-path: Received: from 8bytes.org ([88.198.83.132]:47449 "EHLO 8bytes.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753672AbYIYV1u (ORCPT ); Thu, 25 Sep 2008 17:27:50 -0400 Content-Disposition: inline In-Reply-To: Sender: kvm-owner@vger.kernel.org List-ID: On Thu, Sep 25, 2008 at 09:55:27PM +0200, Alexander Graf wrote: > > On 25.09.2008, at 20:47, Joerg Roedel wrote: > > >I had another possible idea for performance improvement here. Since we > >only inject normal interrupts and exceptions (and not NMI and such) we > >can patch clgi to cli and stgi to sti to save these two intercepts in > >the guests vmrun path. > >Any objections/problems with this? > > How do we know if we're allowed to inject interrupts with V_INTR set? > Usually IF is on and GIF is off when entering the VM in KVM, so we > allow interrupts to arrive even when IF is clear in the guest... Hmm yes, this is a problem. So this optimization will not work. We need other ways to optimize :) Joerg