From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:39291) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1co9wl-0003cT-T5 for qemu-devel@nongnu.org; Wed, 15 Mar 2017 10:30:46 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1co9wl-0004Yj-0E for qemu-devel@nongnu.org; Wed, 15 Mar 2017 10:30:39 -0400 Date: Wed, 15 Mar 2017 15:30:32 +0100 From: Kevin Wolf Message-ID: <20170315143032.GK4030@noname.str.redhat.com> References: <20170314171120.80741-1-vsementsov@virtuozzo.com> <20170315110351.GG4030@noname.str.redhat.com> <9a68a30f-8765-ca91-572f-ed8d7083b202@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <9a68a30f-8765-ca91-572f-ed8d7083b202@redhat.com> Subject: Re: [Qemu-devel] [PATCH] blk: fix aio context loss on media change List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini Cc: Vladimir Sementsov-Ogievskiy , qemu-block@nongnu.org, qemu-devel@nongnu.org, mreitz@redhat.com, jsnow@redhat.com, famz@redhat.com, den@openvz.org, stefanha@redhat.com Am 15.03.2017 um 14:39 hat Paolo Bonzini geschrieben: > On 15/03/2017 12:03, Kevin Wolf wrote: > > But we discussed this earlier, and while I'm not completely sure any > > more about the details, I seem to remeber that Paolo said something > > along the lines that AioContext is going away anyway and building the > > code for proper management would be wasted time. > > AioContext is going to stay, but everybody will be able to send > operations to a BB/BDS from any AioContext. The BDS AioContext will > only matter for network devices, since they have to attach the file > descriptor handlers somewhere. For files it won't matter at all because > you can use multiple Linux AIO context or thread pools at the same time. Should the iothread option then become a -blockdev option rather than a -device one? > There should be a policy on which BB sets AioContext on the BDS (e.g. > only the device does it), but apart from that, it should not be an issue. We don't know which BBs are going to be attached. We don't necessarily have a device at all, or we could have two of them. Though maybe we should try to keep a BDS and its children in the same AioContext anyway if that's possible? Will it make a difference? Kevin