From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:38936) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1apxvx-0004ei-Ak for qemu-devel@nongnu.org; Tue, 12 Apr 2016 09:00:49 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1apxvt-0007Ng-9H for qemu-devel@nongnu.org; Tue, 12 Apr 2016 09:00:45 -0400 Received: from mail-lf0-x233.google.com ([2a00:1450:4010:c07::233]:35622) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1apxvt-0007NU-1N for qemu-devel@nongnu.org; Tue, 12 Apr 2016 09:00:41 -0400 Received: by mail-lf0-x233.google.com with SMTP id c126so23931234lfb.2 for ; Tue, 12 Apr 2016 06:00:40 -0700 (PDT) References: <1459870344-16773-1-git-send-email-alex.bennee@linaro.org> <1459870344-16773-9-git-send-email-alex.bennee@linaro.org> <570C0E16.1030304@gmail.com> <87mvozyrmo.fsf@linaro.org> <570CED19.7000301@gmail.com> <570CEF21.4000302@greensocs.com> From: Sergey Fedorov Message-ID: <570CF175.8090807@gmail.com> Date: Tue, 12 Apr 2016 16:00:37 +0300 MIME-Version: 1.0 In-Reply-To: <570CEF21.4000302@greensocs.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Subject: Re: [Qemu-devel] [RFC v2 08/11] tcg: add options for enabling MTTCG List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: KONRAD Frederic , Peter Maydell , =?UTF-8?Q?Alex_Benn=c3=a9e?= Cc: MTTCG Devel , Alvise Rigo , "Emilio G. Cota" , QEMU Developers , Mark Burton , Paolo Bonzini , "J. Kiszka" , Richard Henderson , Claudio Fontana , Peter Crosthwaite , =?UTF-8?Q?Andreas_F=c3=a4rber?= On 12/04/16 15:50, KONRAD Frederic wrote: > > > Le 12/04/2016 14:42, Sergey Fedorov a écrit : >> On 12/04/16 14:59, Peter Maydell wrote: >>> On 12 April 2016 at 12:48, Alex Bennée wrote: >>>> Sergey Fedorov writes: >>>>> Maybe we'd better use existing qemu accelerator framework and >>>>> introduce >>>>> "-machine accel=mttcg" option? >>>> My worry would be breaking existing code which assumes kvm | tcg. We >>>> will want to enable mttcg by default for combos that work without >>>> having >>>> to tweak tooling that already uses the -machine options. >>> Comments from the peanut gallery: >>> * We definitely want to just default to MTTCG where it works: >>> users shouldn't have to add new command line switches to get the >>> better performance etc, because in practice that won't happen >>> * Anything that adds a new command line option at all has to >>> be supported practically forever, so options that are only >>> useful for a transitional period are worth thinking twice about >> >> Yes, but users may like to have an option to disable MTTCG for some >> reason. I'm also concerned about icount mode: not sure how to account >> virtual time when all vCPUs run in parallel. >> > > > I'm thinking the same, we don't have a solution for icount yet. > The reverse execution support is probably badly broken as well. Reverse execution doesn't even seem to support more than a single core. As of icount, it looks like to be incompatible with MTTCG. Kind regards, Sergey