From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:59904) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SXWkZ-00024w-5R for qemu-devel@nongnu.org; Thu, 24 May 2012 08:02:45 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1SXWkS-0001vG-SR for qemu-devel@nongnu.org; Thu, 24 May 2012 08:02:38 -0400 Received: from mx1.redhat.com ([209.132.183.28]:40362) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SXWkS-0001v1-KR for qemu-devel@nongnu.org; Thu, 24 May 2012 08:02:32 -0400 Message-ID: <4FBE2352.7090401@redhat.com> Date: Thu, 24 May 2012 14:02:26 +0200 From: Paolo Bonzini MIME-Version: 1.0 References: <1337786045-2277-1-git-send-email-zwu.kernel@gmail.com> <1337786045-2277-16-git-send-email-zwu.kernel@gmail.com> <4FBD0995.8030907@redhat.com> <4FBE085E.3060104@redhat.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v2 15/15] net: invoke qemu_can_send_packet only before net queue sending function List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Zhi Yong Wu Cc: wuzhy@linux.vnet.ibm.com, linuxram@us.ibm.com, qemu-devel@nongnu.org, kvm@vger.kernel.org, stefanha@linux.vnet.ibm.com Il 24/05/2012 13:58, Zhi Yong Wu ha scritto: >> > But you will copy packets uselessly. The code before the patch simply >> > left them on the tap file descriptor. This is better because it >> > involves the kernel in flow control. You are introducing "bufferbloat". > You are correct, but can_send_packet will be invoked twice for one > packet delivery. Doesn't matter, it's cheap. Paolo