From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757634Ab2FFSym (ORCPT ); Wed, 6 Jun 2012 14:54:42 -0400 Received: from shards.monkeyblade.net ([149.20.54.216]:38316 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752410Ab2FFSyl (ORCPT ); Wed, 6 Jun 2012 14:54:41 -0400 Date: Wed, 06 Jun 2012 11:54:40 -0700 (PDT) Message-Id: <20120606.115440.1245419453265419850.davem@davemloft.net> To: cmetcalf@tilera.com Cc: eric.dumazet@gmail.com, bhutchings@solarflare.com, arnd@arndb.de, linux-kernel@vger.kernel.org, netdev@vger.kernel.org Subject: Re: [PATCH v9] tilegx network driver: initial support From: David Miller In-Reply-To: <4FCFA312.4020505@tilera.com> References: <201206042023.q54KNEZp003834@farm-0002.internal.tilera.com> <1339004459.26966.31.camel@edumazet-glaptop> <4FCFA312.4020505@tilera.com> X-Mailer: Mew version 6.5 on Emacs 23.3 / Mule 6.0 (HANACHIRUSATO) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Chris Metcalf Date: Wed, 6 Jun 2012 14:36:02 -0400 > By the way, your question about tx_queue_len is a good one; I'm roping in > our other network developer folks to figure it out. Originally it was a > performance optimization, I believe; I'm not sure it's still required. It's illegal, you cannot do this. If you set the TX queue length to zero, amongst other very serious and grave problems, your device cannot be used with the various packet scheduler queueing disciplies. Zero TX queue lengths should only be used for layering drivers which are purely software entities rather than for real actual hardware. As stated before, all of the areas where the tilegx driver tries to be different end up being bugs. It would therefore be nice, if, as I suggested before, the driver is audited by you against a known gold-standard Linux driver such as tg3 to spot inconsistencies like this.