From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:43990) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1er1QW-0004pe-U9 for qemu-devel@nongnu.org; Wed, 28 Feb 2018 08:05:46 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1er1QR-0007XQ-Vn for qemu-devel@nongnu.org; Wed, 28 Feb 2018 08:05:44 -0500 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:32838 helo=mx1.redhat.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1er1QR-0007WX-RT for qemu-devel@nongnu.org; Wed, 28 Feb 2018 08:05:39 -0500 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 6CCC2402290A for ; Wed, 28 Feb 2018 13:05:39 +0000 (UTC) Date: Wed, 28 Feb 2018 21:05:26 +0800 From: Peter Xu Message-ID: <20180228130526.GK27381@xz-mi> References: <20180228050633.7410-1-peterx@redhat.com> <20180228050633.7410-14-peterx@redhat.com> <20180228092356.GF31550@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20180228092356.GF31550@redhat.com> Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH 13/14] qio: allow threaded qiotask to switch contexts List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Cc: qemu-devel@nongnu.org, Paolo Bonzini , Juan Quintela , Markus Armbruster , =?utf-8?Q?Marc-Andr=C3=A9?= Lureau , Stefan Hajnoczi , "Dr . David Alan Gilbert" On Wed, Feb 28, 2018 at 09:23:56AM +0000, Daniel P. Berrang=C3=A9 wrote: > On Wed, Feb 28, 2018 at 01:06:32PM +0800, Peter Xu wrote: > > This is the part of work to allow the QIOTask to use a different > > gcontext rather than the default main gcontext, by providing > > qio_task_context_set() API. > >=20 > > We have done some work before on doing similar things to add non-defa= ult > > gcontext support. The general idea is that we delete the old GSource > > from the main context, then re-add a new one to the new context when > > context changed to a non-default one. However this trick won't work > > easily for threaded QIOTasks since we can't easily stop a real thread > > and re-setup the whole thing from the very beginning. >=20 > I think this entire usage pattern is really broken. We should not > provide a way to change the GMainContext on an existing task. We > should always just set the correct GMainContxt right from the start. > This will avoid much of the complexity you're introducing into this > patch series, and avoid having to expose GTasks to the callers of > the async methods at all. Yeah I agree with you that the threaded QIO patches are complicated. Then how about I introduce: - qio_task_thread_new(): to create QIO task and its thread (but not running) - qio_task_thread_run(): to run the thread Then I can setup the context correctly between the two in some way. After that, qio_task_run_in_thread() will be two calls of above two APIs. Thanks, --=20 Peter Xu