From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=44989 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1PmkEn-0004Bu-88 for qemu-devel@nongnu.org; Tue, 08 Feb 2011 04:51:58 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1PmkEm-0003eB-2T for qemu-devel@nongnu.org; Tue, 08 Feb 2011 04:51:57 -0500 Received: from david.siemens.de ([192.35.17.14]:28184) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1PmkEl-0003dq-MC for qemu-devel@nongnu.org; Tue, 08 Feb 2011 04:51:56 -0500 Message-ID: <4D511221.9030505@siemens.com> Date: Tue, 08 Feb 2011 10:51:29 +0100 From: Jan Kiszka MIME-Version: 1.0 References: <4D3DFD20.8060004@linux.vnet.ibm.com> <20110125091741.GB30239@edde.se.axis.com> <20110125133453.GC5427@amt.cnet> <20110207101255.GA20413@amt.cnet> <20110207160350.GA26332@amt.cnet> <4D501C71.7090708@redhat.com> <4D50279B.5010102@siemens.com> <4D505DCB.9050406@codemonkey.ws> <20110207214551.GB16429@hall.aurel32.net> <4D50A5F0.802@codemonkey.ws> <20110208072657.GD16429@hall.aurel32.net> <4D50FA14.5010100@redhat.com> <4D5103E8.6050808@siemens.com> <4D510771.3040309@aurel32.net> In-Reply-To: <4D510771.3040309@aurel32.net> Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: quoted-printable Subject: [Qemu-devel] Re: [PATCH 2/7] Enable I/O thread and VNC threads by default List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Aurelien Jarno Cc: Anthony Liguori , Stefan Hajnoczi , Marcelo Tosatti , "qemu-devel@nongnu.org" , Anthony Liguori , Paul Brook , "Edgar E. Iglesias" , Paolo Bonzini , Arun Bharadwaj On 2011-02-08 10:05, Aurelien Jarno wrote: > Jan Kiszka a =E9crit : >> On 2011-02-08 09:08, Paolo Bonzini wrote: >>> On 02/08/2011 08:26 AM, Aurelien Jarno wrote: >>>> I forget to remember when we decided that AIO should be implemented = on >>>> any host OS. Any pointer? >>> To be fair, I/O-heavy workloads are almost unusable without AIO. For= =20 >>> Window targets, they also crash under SMP due to the Windows AP=20 >>> watchdog. But then TCG and SMP do not go very well together anyway. >>> >>> However, I think deprecating Win32 support would be a very bad idea. >> >> It would be too early at this point. >> >> But if Windows is once the only reason to keep tons of hardly tested >> code paths around or to invest significant additional effort to change >> logic or interfaces in this area, than I would prefer that step. I'm >> hacking on IOTHREAD vs. !IOTHREAD for some weeks now, and all those >> subtle differences are really a PITA and source of various breakages. >> >> People interested in that platform should finally realize that its fat= e >> is coupled to reducing the #ifdefs as well as the design differences w= e >> see right now and even more in the future. >> >=20 > The guilty here is IOTHREAD. Windows support predates IOTHREAD concept, > it's just that people who introduce IOTHREAD didn't care about Windows > support at all and added these #ifdef. Disabling Windows support becaus= e > of that is not fair. The TCG execution model won't scale long-term. It's already a main to boot a quad or just dual core VM, even more when your host has at least as many real cores. I'm sure we'll see multi-threaded TCG CPUs in the future, and the iothread will just be one of 7, 17 or 257 threads. Jan --=20 Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux