From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH net-next 2/2] bnx2x: use the default NAPI weight Date: Tue, 05 Mar 2013 23:37:44 -0500 (EST) Message-ID: <20130305.233744.498353801662910535.davem@davemloft.net> References: <1362535067.15793.146.camel@edumazet-glaptop> <20130305.210909.1826827522208936437.davem@davemloft.net> <1362540509.15793.158.camel@edumazet-glaptop> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, eilong@broadcom.com To: eric.dumazet@gmail.com Return-path: Received: from shards.monkeyblade.net ([149.20.54.216]:60686 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751354Ab3CFEhp (ORCPT ); Tue, 5 Mar 2013 23:37:45 -0500 In-Reply-To: <1362540509.15793.158.camel@edumazet-glaptop> Sender: netdev-owner@vger.kernel.org List-ID: From: Eric Dumazet Date: Tue, 05 Mar 2013 19:28:29 -0800 > We are facing a fanout/fanin problem for a given application. > > What happens is that link is mostly idle, and every couple of minutes, > we receive a burst of messages, needing a burst of transmits. > > BQL starts with a limit of 0, meaning it needs some TX completion runs > to be able to detect the sudden increase of TX need and reach line rate. > > bnx2x is really unfair in this scenario, because the NAPI poll budget is > very high, and aggregated packets (by LRO) count for a single packet in > the budget. (or even 0, see the "goto next_cqe;" that avoids the rx_pkt > ++; in drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c line 1007) > > We probably have other issues in the stack, I am patiently finding all > of them. In the mean time we had to disable BQL :( Thanks for the explanation. Since you haven't completely resolved the issues you were running into I'll target this to net-next for now. Thanks!