From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:37411) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VTWVu-0006fI-CJ for qemu-devel@nongnu.org; Tue, 08 Oct 2013 08:35:53 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1VTWVl-0000q4-St for qemu-devel@nongnu.org; Tue, 08 Oct 2013 08:35:45 -0400 Received: from mx1.redhat.com ([209.132.183.28]:30435) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VTWVl-0000pn-I1 for qemu-devel@nongnu.org; Tue, 08 Oct 2013 08:35:37 -0400 Message-ID: <5253FC11.3010309@redhat.com> Date: Tue, 08 Oct 2013 14:35:29 +0200 From: Paolo Bonzini MIME-Version: 1.0 References: <1380728469-29435-1-git-send-email-pl@kamp.de> <524C3FCE.4090908@redhat.com> <20131008123315.GE25109@dhcp-200-207.str.redhat.com> In-Reply-To: <20131008123315.GE25109@dhcp-200-207.str.redhat.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] block/iscsi: introduce bdrv_co_{readv, writev, flush_to_disk} List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Kevin Wolf Cc: ronniesahlberg@gmail.com, Peter Lieven , qemu-devel@nongnu.org, stefanha@redhat.com Il 08/10/2013 14:33, Kevin Wolf ha scritto: >>> > > this converts read, write and flush functions from aio to coroutines. >> > >> > I'm not sure it's already the time for this... Cancellation sucks in >> > QEMU, and this is going to make things even worse. > Not sure what you're referring to. If you mean iscsi_aio_cancel(), isn't > it dead code anyway since we changed block.c to use coroutines for > everything? bdrv_co_io_em() even throws the acb away, so even if you > wanted, there's no way to cancel the request even today. SCSI tries to use cancellation, and this results in VCPU threads starving all other threads. So I would like to introduce cancellation points for coroutines. Paolo