From mboxrd@z Thu Jan 1 00:00:00 1970 From: Neal Cardwell Subject: Re: Is 3.18 patch "The tcp: TSO packets automatic sizing" will cause to Troughput drop when enable NO_HZ_IDEL or HIGH_RES_TIMERS ? Date: Tue, 6 May 2014 12:48:27 -0400 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Cc: Netdev To: V JobNickname Return-path: Received: from mail-we0-f178.google.com ([74.125.82.178]:45647 "EHLO mail-we0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750782AbaEFQs3 (ORCPT ); Tue, 6 May 2014 12:48:29 -0400 Received: by mail-we0-f178.google.com with SMTP id u56so8539748wes.9 for ; Tue, 06 May 2014 09:48:28 -0700 (PDT) In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: On Tue, May 6, 2014 at 12:17 PM, V JobNickname wrote: > More detail trace, the first commit of 3.10.18, tcp: TSO packets > automatic sizing, cause to this issue. > https://git.kernel.org/cgit/linux/kernel/git/stable/linux-stable.git/diff/?id=5e25ba5003ee5de0ba2be56bfd54d16d4b1b028d To provide another data point, it would be interesting to know what performance you see with v3.15-rc4. Linux 3.15 has the following patch: 740b0f1841f6 tcp: switch rtt estimations to usec resolution That patch switches tcp_update_pacing_rate() to use microsecond RTTs for its calculation. That may help things in your case. (As Eric says, more details would help.) > I don't know why this TSO patch affect my network since the network > driver doesn't enable NETIF_F_TSO. Keep in mind that anytime the Linux TCP code or commit descriptions talk about "TSO", the same applies to GSO. Is GSO enabled for your device? neal