From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 34634C28CF6 for ; Wed, 1 Aug 2018 18:24:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D4CA620841 for ; Wed, 1 Aug 2018 18:24:27 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D4CA620841 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linuxfoundation.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733094AbeHAULZ (ORCPT ); Wed, 1 Aug 2018 16:11:25 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:46084 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2404341AbeHATDi (ORCPT ); Wed, 1 Aug 2018 15:03:38 -0400 Received: from localhost (D57E6652.static.ziggozakelijk.nl [213.126.102.82]) by mail.linuxfoundation.org (Postfix) with ESMTPSA id 81BA312FB; Wed, 1 Aug 2018 17:11:33 +0000 (UTC) From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Eric Dumazet , Soheil Hassas Yeganeh , Yuchung Cheng , Neal Cardwell , "David S. Miller" Subject: [PATCH 4.17 331/336] tcp: do not aggressively quick ack after ECN events Date: Wed, 1 Aug 2018 18:51:06 +0200 Message-Id: <20180801165041.696996388@linuxfoundation.org> X-Mailer: git-send-email 2.18.0 In-Reply-To: <20180801165028.930831994@linuxfoundation.org> References: <20180801165028.930831994@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.17-stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet [ Upstream commit 522040ea5fdd1c33bbf75e1d7c7c0422b96a94ef ] ECN signals currently forces TCP to enter quickack mode for up to 16 (TCP_MAX_QUICKACKS) following incoming packets. We believe this is not needed, and only sending one immediate ack for the current packet should be enough. This should reduce the extra load noticed in DCTCP environments, after congestion events. This is part 2 of our effort to reduce pure ACK packets. Signed-off-by: Eric Dumazet Acked-by: Soheil Hassas Yeganeh Acked-by: Yuchung Cheng Acked-by: Neal Cardwell Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/ipv4/tcp_input.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -245,7 +245,7 @@ static void __tcp_ecn_check_ce(struct tc * it is probably a retransmit. */ if (tp->ecn_flags & TCP_ECN_SEEN) - tcp_enter_quickack_mode((struct sock *)tp, TCP_MAX_QUICKACKS); + tcp_enter_quickack_mode((struct sock *)tp, 1); break; case INET_ECN_CE: if (tcp_ca_needs_ecn((struct sock *)tp)) @@ -253,7 +253,7 @@ static void __tcp_ecn_check_ce(struct tc if (!(tp->ecn_flags & TCP_ECN_DEMAND_CWR)) { /* Better not delay acks, sender can have a very low cwnd */ - tcp_enter_quickack_mode((struct sock *)tp, TCP_MAX_QUICKACKS); + tcp_enter_quickack_mode((struct sock *)tp, 1); tp->ecn_flags |= TCP_ECN_DEMAND_CWR; } tp->ecn_flags |= TCP_ECN_SEEN;