From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH] stmmac: reduce queue lengths if MTU is very large Date: Tue, 20 Dec 2011 13:41:20 -0500 (EST) Message-ID: <20111220.134120.1764634344589128309.davem@davemloft.net> References: <20111219.163337.1185514300243434827.davem@davemloft.net> <1324273530-18499-1-git-send-email-peppe.cavallaro@st.com> <20111220073050.GA2817@mail.gnudd.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: peppe.cavallaro@st.com, netdev@vger.kernel.org, giancarlo.asnaghi@st.com To: rubini@gnudd.com Return-path: Received: from shards.monkeyblade.net ([198.137.202.13]:41950 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752002Ab1LTSl3 (ORCPT ); Tue, 20 Dec 2011 13:41:29 -0500 In-Reply-To: <20111220073050.GA2817@mail.gnudd.com> Sender: netdev-owner@vger.kernel.org List-ID: From: Alessandro Rubini Date: Tue, 20 Dec 2011 08:30:50 +0100 > Allocation of the queues is based on a parameter. If the parameter was > a size, instead of a lenght, all would be fine, wouldn't it? If you > agree, then this patch is turning the lenght into a size, in a way. That doesn't make any sense either, queues are sized by TX descriptor slots not bytes. > Now, how could we deal with the fact that the size explodes if the MTU > is increased? Maybe... set the initial parameter appropriately? This is enormously better than fixing it up after the fact. Maybe I set the number of TX entries based upon my expected packet load of small packets. If I happen to set my MTU to 9000 that's irrelevant to the setting.