From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wg0-x231.google.com (mail-wg0-x231.google.com [IPv6:2a00:1450:400c:c00::231]) by dpdk.org (Postfix) with ESMTP id 5DF886833 for ; Wed, 3 Jul 2013 08:02:44 +0200 (CEST) Received: by mail-wg0-f49.google.com with SMTP id a12so5267592wgh.28 for ; Tue, 02 Jul 2013 23:02:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:from:date:message-id:subject:to:content-type; bh=ZzCQNXHe+20z7yblFR9yQEsr/8xY+SbQFPHbL48f7yw=; b=TFvLSGdpb0AICPTuGdGaBI4jVb+b5Ym+M/M4wjRaWbIgjVkjxkZ0IfpsD59wrsHiMX Juh794nGK2ZAHD84PP6nIhy/79c3c3kgQod7jPqznJ2FWyWu5SYEdOKGNFy7gaMFmQuP lLI/Cxye+Pw+cdGuQkfD7G5d8O2B2FiY+JZ1zgdIO0z9NH4x6MWCqExuaCbZE/tx7AZ9 hvFCYtfK1N3y5mc3GmijLbPMl06TXevDN5c39kydiFQ3mgdDK1XRBVUlwXtltyVTN1AW K9LH6D2kVm+dGpB8iMr3ukXZxDfbMfgr1PO6K+bx+rC/Mx4yQZv7v00fT1BUcglcI+tz +yOA== X-Received: by 10.194.119.195 with SMTP id kw3mr25216953wjb.64.1372831378688; Tue, 02 Jul 2013 23:02:58 -0700 (PDT) MIME-Version: 1.0 Received: by 10.216.234.4 with HTTP; Tue, 2 Jul 2013 23:02:38 -0700 (PDT) From: Peter Chen Date: Tue, 2 Jul 2013 23:02:38 -0700 Message-ID: To: dev@dpdk.org Content-Type: multipart/alternative; boundary=089e01228946a9d15604e09536c3 Subject: [dpdk-dev] Transmit and Receive Queue: Prefetch, Host, Writeback X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 03 Jul 2013 06:02:44 -0000 --089e01228946a9d15604e09536c3 Content-Type: text/plain; charset=ISO-8859-1 I looked at the description for transmit and receive queue configurations in the Programmar's Guide, but was confused by how the configuration worked. I am assuming that one descriptor in the queue refers to one pktmbuf? I am not sure what prefetch, host and writeback of queue descriptors mean for the receive and transmission queues. Can anyone explain to me what they mean? Also tx_free_threshold is described as the number of descriptors used to transmit packets before they are freed and written back to the host memory, so in that sense what does rx_free_threshold stand for? Does that mean the NIC has to receive x number of descriptors to receive packets before moving them up to user space? Another point of confusion is this sentence about tx_rs_threshold: "The RS bit is set on the last descriptor used to transmit a packet if the number of descriptors used since the last RS bit setting, up to the first descriptor used to transmit the packet, exceeds the transmit RS bit threshold (tx_rs_thresh)".. If anyone know what these means, it would be great! --089e01228946a9d15604e09536c3 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable
I looked at the description for transmit and receive queue= configurations in the Programmar's Guide, but was confused by how the = configuration worked. I am assuming that one descriptor in the queue refers= to one pktmbuf?=A0

I am not sure what prefetch, host and writeback of que= ue descriptors mean for the receive and transmission queues. Can anyone exp= lain to me what they mean?

Also tx_free_threshold is described as th= e number of descriptors used to transmit packets before they are freed and = written back to the host memory, so in that sense what does rx_free_thresho= ld stand for? Does that mean the NIC has to receive x number of descriptors= to receive packets before moving them up to user space?

Another point of confusion is this sentence about tx_rs_threshold: &quo= t;The RS bit is=A0
set on the last descriptor used to transmit a = packet if the number of descriptors=A0
used since the last RS bit= setting, up to the first descriptor used to transmit the=A0
packet, exceeds the transmit RS bit threshold (tx_rs_thresh)"..= =A0

If anyone know what these means, it would be great!
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