From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:56776) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XuPOf-0007Q0-AE for qemu-devel@nongnu.org; Fri, 28 Nov 2014 12:32:06 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XuPOT-000868-UR for qemu-devel@nongnu.org; Fri, 28 Nov 2014 12:31:57 -0500 Received: from mail-wi0-x229.google.com ([2a00:1450:400c:c05::229]:34804) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XuPOT-00085z-Nv for qemu-devel@nongnu.org; Fri, 28 Nov 2014 12:31:45 -0500 Received: by mail-wi0-f169.google.com with SMTP id r20so21420255wiv.4 for ; Fri, 28 Nov 2014 09:31:44 -0800 (PST) Sender: Paolo Bonzini Message-ID: <5478B17B.2020605@redhat.com> Date: Fri, 28 Nov 2014 18:31:39 +0100 From: Paolo Bonzini MIME-Version: 1.0 References: <1417183941-26329-1-git-send-email-pbonzini@redhat.com> <1417183941-26329-6-git-send-email-pbonzini@redhat.com> <20141128164023.GH4035@noname.redhat.com> In-Reply-To: <20141128164023.GH4035@noname.redhat.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 5/7] coroutine: rewrite pool to avoid mutex List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Kevin Wolf Cc: ming.lei@canonical.com, pl@kamp.de, qemu-devel@nongnu.org, stefanha@redhat.com On 28/11/2014 17:40, Kevin Wolf wrote: >> > I still believe we will end with some kind of coroutine bypass scheme >> > (even coroutines _do_ allocate an AIOCB, so calling bdrv_aio_readv >> > directly can help), but hey it cannot hurt to optimize hot code. > > Not sure if speculations about the future belong into commit messages, > but while it may turn out that a bypass is required in the end (I hope > it doesn't), the part about AIOCBs is wrong if you really consistently > use coroutines all the way down from the device to the block driver. This is much harder for virtio-scsi than for virtio-blk, though. Paolo