From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=34723 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1Pmjcf-0007Fs-QL for qemu-devel@nongnu.org; Tue, 08 Feb 2011 04:12:35 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Pmjcc-0002dk-1X for qemu-devel@nongnu.org; Tue, 08 Feb 2011 04:12:33 -0500 Received: from mail-wy0-f173.google.com ([74.125.82.173]:58937) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Pmjcb-0002dT-OI for qemu-devel@nongnu.org; Tue, 08 Feb 2011 04:12:29 -0500 Received: by wyg36 with SMTP id 36so5756252wyg.4 for ; Tue, 08 Feb 2011 01:12:28 -0800 (PST) Message-ID: <4D5108F6.6070605@codemonkey.ws> Date: Tue, 08 Feb 2011 03:12:22 -0600 From: Anthony Liguori MIME-Version: 1.0 Subject: Re: [Qemu-devel] Re: [PATCH 2/7] Enable I/O thread and VNC threads by default 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; format=flowed Content-Transfer-Encoding: 8bit List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Aurelien Jarno Cc: Stefan Hajnoczi , Jan Kiszka , Marcelo Tosatti , "qemu-devel@nongnu.org" , Anthony Liguori , Paul Brook , Paolo Bonzini , "Edgar E. Iglesias" , Arun Bharadwaj On 02/08/2011 03:05 AM, Aurelien Jarno wrote: > Jan Kiszka a écrit : > >> 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 >>> Window targets, they also crash under SMP due to the Windows AP >>> 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 fate >> is coupled to reducing the #ifdefs as well as the design differences we >> see right now and even more in the future. >> >> > The guilty here is IOTHREAD. Windows support predates IOTHREAD concept, > IOTHREAD is actually just as necessary for TCG as it is for KVM. Otherwise, you have a signal select race that cannot be avoided. QEMU has never "supported" Windows. It happens to compile on Windows, but historically the Windows build has been non-functional for long periods of time and is still missing basic features (like AIO). Regards, Anthony Liguori > it's just that people who introduce IOTHREAD didn't care about Windows > support at all and added these #ifdef. Disabling Windows support because > of that is not fair. > > We should probably get rid of KVM support in QEMU, so if someone has an > idea for a cool TCG feature that can't be supported in KVM, it's the > moment to submit it. We can add it with #ifdef, and in one year just ask > for KVM support removal. > >