From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760886Ab3DCCDU (ORCPT ); Tue, 2 Apr 2013 22:03:20 -0400 Received: from shards.monkeyblade.net ([149.20.54.216]:51347 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757040Ab3DCCDR (ORCPT ); Tue, 2 Apr 2013 22:03:17 -0400 Date: Tue, 02 Apr 2013 22:03:15 -0400 (EDT) Message-Id: <20130402.220315.1782012687105065631.davem@davemloft.net> To: alan@signal11.us Cc: werner@almesberger.net, netdev@vger.kernel.org, linux-zigbee-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org Subject: Re: [Linux-zigbee-devel] [PATCH 1/6] mac802154: Immediately retry sending failed packets From: David Miller In-Reply-To: <515B8D09.9050304@signal11.us> References: <515B84EB.8020006@signal11.us> <20130402.215625.1555279506975246223.davem@davemloft.net> <515B8D09.9050304@signal11.us> X-Mailer: Mew version 6.5 on Emacs 24.1 / Mule 6.0 (HANACHIRUSATO) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.2.7 (shards.monkeyblade.net [0.0.0.0]); Tue, 02 Apr 2013 19:03:16 -0700 (PDT) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Alan Ott Date: Tue, 02 Apr 2013 21:59:37 -0400 > On 04/02/2013 09:56 PM, David Miller wrote: >> From: Alan Ott >> Date: Tue, 02 Apr 2013 21:24:59 -0400 >> >>> I like it for a couple of reasons. >>> 1. Most supported devices have only single packet output buffer, so >>> blocking in the driver is the most straight-forward way to handle it. >>> The alternative is to make each driver have a workqueue for xmit() (to >>> lift the blocking out from atomic context). This makes each driver simpler. >>> >>> 2. All of the flow control can be handled one time in the mac802154 layer. >> We have a perfectly working flow control mechanism in the generic >> networking queuing layer. Please use it instead of inventing things. > > I'm pretty sure that's what I'm doing in [1]. When I say "flow control > can be handled," I mean managing calls to netif_stop_queue() and > netif_wake_queue(). Is there something else I should be doing instead? Then you shouldn't need workqueues if the generic netdev facilities can do the flow control properly. There are several ethernet devices that have a single transmit buffer and function just fine, and optimally, solely using the transmit queue stop/start/wake infrastructure. From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH 1/6] mac802154: Immediately retry sending failed packets Date: Tue, 02 Apr 2013 22:03:15 -0400 (EDT) Message-ID: <20130402.220315.1782012687105065631.davem@davemloft.net> References: <515B84EB.8020006@signal11.us> <20130402.215625.1555279506975246223.davem@davemloft.net> <515B8D09.9050304@signal11.us> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-zigbee-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org To: alan-yzvJWuRpmD1zbRFIqnYvSA@public.gmane.org Return-path: In-Reply-To: <515B8D09.9050304-yzvJWuRpmD1zbRFIqnYvSA@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linux-zigbee-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: netdev.vger.kernel.org From: Alan Ott Date: Tue, 02 Apr 2013 21:59:37 -0400 > On 04/02/2013 09:56 PM, David Miller wrote: >> From: Alan Ott >> Date: Tue, 02 Apr 2013 21:24:59 -0400 >> >>> I like it for a couple of reasons. >>> 1. Most supported devices have only single packet output buffer, so >>> blocking in the driver is the most straight-forward way to handle it. >>> The alternative is to make each driver have a workqueue for xmit() (to >>> lift the blocking out from atomic context). This makes each driver simpler. >>> >>> 2. All of the flow control can be handled one time in the mac802154 layer. >> We have a perfectly working flow control mechanism in the generic >> networking queuing layer. Please use it instead of inventing things. > > I'm pretty sure that's what I'm doing in [1]. When I say "flow control > can be handled," I mean managing calls to netif_stop_queue() and > netif_wake_queue(). Is there something else I should be doing instead? Then you shouldn't need workqueues if the generic netdev facilities can do the flow control properly. There are several ethernet devices that have a single transmit buffer and function just fine, and optimally, solely using the transmit queue stop/start/wake infrastructure. ------------------------------------------------------------------------------ Minimize network downtime and maximize team effectiveness. Reduce network management and security costs.Learn how to hire the most talented Cisco Certified professionals. Visit the Employer Resources Portal http://www.cisco.com/web/learning/employer_resources/index.html