From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH 0/6] Add rudimentary Hyper-V guest support Date: Mon, 18 May 2009 00:08:49 +0300 Message-ID: <4A107CE1.2030707@redhat.com> References: <1242375740-31222-1-git-send-email-agraf@suse.de> <0EF5ED01-F027-470C-B766-3DB8EF616AE8@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: KVM list , Joerg Roedel To: Alexander Graf Return-path: Received: from mx2.redhat.com ([66.187.237.31]:35753 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752224AbZEQVI5 (ORCPT ); Sun, 17 May 2009 17:08:57 -0400 In-Reply-To: <0EF5ED01-F027-470C-B766-3DB8EF616AE8@suse.de> Sender: kvm-owner@vger.kernel.org List-ID: Alexander Graf wrote: > In order to find out why things were slow with nested SVM I hacked > intercept reporting into debugfs in my local tree and found pretty > interesting results (using NPT): > > [...] > So apparently the most intercepts come from the SVM helper calls > (clgi, stgi, vmload, vmsave). I guess I need to get back to the > "emulate when GIF=0" approach to get things fast. There's only a limited potential here (a factor of three, reducing 6 exits to 2, less the emulation overhead). There's a lot more to be gained from nested npt, since you'll avoid most of the original exits in the first place. -- Do not meddle in the internals of kernels, for they are subtle and quick to panic.