From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH net 1/1] net/mlx5e: Set EQE based as default TX interrupt moderation mode Date: Sun, 01 Apr 2018 20:56:44 -0400 (EDT) Message-ID: <20180401.205644.1807066350495572745.davem@davemloft.net> References: <20180330225008.21042-1-saeedm@mellanox.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, talgi@mellanox.com To: saeedm@mellanox.com Return-path: Received: from shards.monkeyblade.net ([184.105.139.130]:59574 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753992AbeDBA4p (ORCPT ); Sun, 1 Apr 2018 20:56:45 -0400 In-Reply-To: <20180330225008.21042-1-saeedm@mellanox.com> Sender: netdev-owner@vger.kernel.org List-ID: From: Saeed Mahameed Date: Fri, 30 Mar 2018 15:50:08 -0700 > From: Tal Gilboa > > The default TX moderation mode was mistakenly set to CQE based. The > intention was to add a control ability in order to improve some specific > use-cases. In general, we prefer to use EQE based moderation as it gives > much better numbers for the common cases. > > CQE based causes a degradation in the common case since it resets the > moderation timer on CQE generation. This causes an issue when TSO is > well utilized (large TSO sessions). The timer is set to 16us so traffic > of ~64KB TSO sessions per second would mean timer reset (CQE per TSO > session -> long time between CQEs). In this case we quickly reach the > tcp_limit_output_bytes (256KB by default) and cause a halt in TX traffic. > > By setting EQE based moderation we make sure timer would expire after > 16us regardless of the packet rate. > This fixes an up to 40% packet rate and up to 23% bandwidth degradtions. > > Fixes: 0088cbbc4b66 ("net/mlx5e: Enable CQE based moderation on TX CQ") > Signed-off-by: Tal Gilboa > Signed-off-by: Saeed Mahameed Applied and queued up for -stable.