From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eyal Perry Subject: BW regression after "tcp: refine TSO autosizing" Date: Tue, 13 Jan 2015 18:48:50 +0200 Message-ID: <54B54C72.8060705@dev.mellanox.co.il> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, Amir Vadai , yevgenyp@mellanox.com, saeedm@mellanox.com, idos@mellanox.com, amira@mellanox.com, eyalpe@mellanox.com To: eric.dumazet@gmail.com Return-path: Received: from mail-wg0-f46.google.com ([74.125.82.46]:42687 "EHLO mail-wg0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751190AbbAMQyP (ORCPT ); Tue, 13 Jan 2015 11:54:15 -0500 Received: by mail-wg0-f46.google.com with SMTP id x13so4110556wgg.5 for ; Tue, 13 Jan 2015 08:54:13 -0800 (PST) Sender: netdev-owner@vger.kernel.org List-ID: Hello Eric, Lately we've observed performance degradation in BW of about 30-40% (depends on the setup we use). I've bisected the issue down to the this commit: 605ad7f1 ("tcp: refine TSO autosizing") For instance, I was running the following test: 1. Bounding net device' irqs to core 0 for both client and server side 2. Running netperf with 64K massage size (used the following command) $ netperf -H remote -T 1,1 -l 100 -t TCP_STREAM -- -k THROUGHPUT -M 65536 -m 65536 I ran the test on upstream net-next including your patch and than reverted it and these are the results I got was improvement from 14.6Gbps to 22.1Gbps. an additional difference I've noticed when inspecting the ethtool statics, number of xmit_more packets increased from 4 to 160 with the reverted kernel. We are investigating this issue, do you have a hint? Best regards, Eyal.