From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anthony Liguori Subject: Re: [Qemu-devel] Anyone seeing huge slowdown launching qemu with Linux 2.6.35? Date: Tue, 03 Aug 2010 11:56:16 -0500 Message-ID: <4C584A30.3030905@codemonkey.ws> References: <20100803111306.GA21886@amd.home.annexia.org> <20100803113302.GT24773@redhat.com> <20100803121000.GV13789@amd.home.annexia.org> <20100803123714.GU24773@redhat.com> <20100803124808.GW13789@amd.home.annexia.org> <4C58176B.2050306@redhat.com> <20100803140506.GD22211@amd.home.annexia.org> <4C5829E1.60004@redhat.com> <20100803145337.GF22211@amd.home.annexia.org> <4C583F6A.7030600@redhat.com> <20100803162857.GX13789@amd.home.annexia.org> <4C584781.9040609@redhat.com> <4C5847CD.9080107@codemonkey.ws> <4C5848C7.3090806@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: "Richard W.M. Jones" , qemu-devel@nongnu.org, Gleb Natapov , kvm@vger.kernel.org To: Avi Kivity Return-path: Received: from mail-qy0-f174.google.com ([209.85.216.174]:52176 "EHLO mail-qy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756725Ab0HCQ4V (ORCPT ); Tue, 3 Aug 2010 12:56:21 -0400 Received: by qyk7 with SMTP id 7so319065qyk.19 for ; Tue, 03 Aug 2010 09:56:20 -0700 (PDT) In-Reply-To: <4C5848C7.3090806@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On 08/03/2010 11:50 AM, Avi Kivity wrote: > On 08/03/2010 07:46 PM, Anthony Liguori wrote: >>> It doesn't appear to support live migration, or hiding the feature >>> for -M older. >>> >>> It's not a good path to follow. Tomorrow we'll need to load 300MB >>> initrds and we'll have to rework this yet again. Meanwhile the >>> kernel and virtio support demand loading of any image size you'd >>> want to use. >> >> >> firmware is totally broken with respect to -M older FWIW. >> > > Well, then this is adding to the brokenness. > > fwcfg dma is going to have exactly one user, libguestfs. Much better > to have libguestfs move to some other interface and improve are > users-to-interfaces ratio. BTW, the brokenness is that regardless of -M older, we always use the newest firmware. Because always use the newest firmware, fwcfg is not a backwards compatible interface. Migration totally screws this up. While we migrate roms (and correctly now thanks to Alex's patches), we size the allocation based on the newest firmware size. That means if we ever decreased the size of a rom, we'd see total failure (even if we had a compatible fwcfg interface). Regards, Anthony Liguori From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=37212 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1OgKn0-0005Kj-8q for qemu-devel@nongnu.org; Tue, 03 Aug 2010 12:56:35 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1OgKms-0002Ab-P4 for qemu-devel@nongnu.org; Tue, 03 Aug 2010 12:56:29 -0400 Received: from mail-qy0-f173.google.com ([209.85.216.173]:43790) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1OgKms-0002A8-Li for qemu-devel@nongnu.org; Tue, 03 Aug 2010 12:56:22 -0400 Received: by qyk35 with SMTP id 35so1061821qyk.4 for ; Tue, 03 Aug 2010 09:56:20 -0700 (PDT) Message-ID: <4C584A30.3030905@codemonkey.ws> Date: Tue, 03 Aug 2010 11:56:16 -0500 From: Anthony Liguori MIME-Version: 1.0 Subject: Re: [Qemu-devel] Anyone seeing huge slowdown launching qemu with Linux 2.6.35? References: <20100803111306.GA21886@amd.home.annexia.org> <20100803113302.GT24773@redhat.com> <20100803121000.GV13789@amd.home.annexia.org> <20100803123714.GU24773@redhat.com> <20100803124808.GW13789@amd.home.annexia.org> <4C58176B.2050306@redhat.com> <20100803140506.GD22211@amd.home.annexia.org> <4C5829E1.60004@redhat.com> <20100803145337.GF22211@amd.home.annexia.org> <4C583F6A.7030600@redhat.com> <20100803162857.GX13789@amd.home.annexia.org> <4C584781.9040609@redhat.com> <4C5847CD.9080107@codemonkey.ws> <4C5848C7.3090806@redhat.com> In-Reply-To: <4C5848C7.3090806@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Avi Kivity Cc: kvm@vger.kernel.org, "Richard W.M. Jones" , Gleb Natapov , qemu-devel@nongnu.org On 08/03/2010 11:50 AM, Avi Kivity wrote: > On 08/03/2010 07:46 PM, Anthony Liguori wrote: >>> It doesn't appear to support live migration, or hiding the feature >>> for -M older. >>> >>> It's not a good path to follow. Tomorrow we'll need to load 300MB >>> initrds and we'll have to rework this yet again. Meanwhile the >>> kernel and virtio support demand loading of any image size you'd >>> want to use. >> >> >> firmware is totally broken with respect to -M older FWIW. >> > > Well, then this is adding to the brokenness. > > fwcfg dma is going to have exactly one user, libguestfs. Much better > to have libguestfs move to some other interface and improve are > users-to-interfaces ratio. BTW, the brokenness is that regardless of -M older, we always use the newest firmware. Because always use the newest firmware, fwcfg is not a backwards compatible interface. Migration totally screws this up. While we migrate roms (and correctly now thanks to Alex's patches), we size the allocation based on the newest firmware size. That means if we ever decreased the size of a rom, we'd see total failure (even if we had a compatible fwcfg interface). Regards, Anthony Liguori