From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:35491) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SUxNA-0004Pv-AS for qemu-devel@nongnu.org; Thu, 17 May 2012 05:51:56 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1SUxN5-0005pR-LQ for qemu-devel@nongnu.org; Thu, 17 May 2012 05:51:51 -0400 Received: from mx1.redhat.com ([209.132.183.28]:25798) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SUxN5-0005pF-D4 for qemu-devel@nongnu.org; Thu, 17 May 2012 05:51:47 -0400 Message-ID: <4FB4CA2D.4080501@redhat.com> Date: Thu, 17 May 2012 11:51:41 +0200 From: Paolo Bonzini MIME-Version: 1.0 References: <4F1EF6CE.9060306@gmail.com> <4F2F0038.3040209@redhat.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [QEMU] net: adapt dump to support the new syntax List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Zhi Yong Wu Cc: Stefan Hajnoczi , Benjamin , qemu-devel Il 17/05/2012 07:59, Zhi Yong Wu ha scritto: >> > However, then I noticed that qemu_can_send_packet is not called very much, >> > and I do not understand why qemu_net_queue_send and qemu_net_queue_send_iov >> > do not call qemu_can_send_packet before calling deliver/deliver_iov. > This case has existed in current upstream code, not only vlan-hub > code. Currently can_send function has been called by backend send > function before deliver/deliver_iov, If we put can_send in queue send > function, your idea will have a big challenge for slirp packet queue. Exactly why? For SLIRP's receive path, SLIRP doesn't implement can_receive at all so it will never block. For the send path, when flow control kicks qemu_net_queue_append will copy the packet so it is not a problem for SLIRP's stack-allocated packets. > We can implement your idea below later, not in this patchset. What do > you think? Note that my idea above was only means to an end. If you can remove the TODOs in a convincing manner, that would be fine. Paolo