From patchwork Mon Apr 8 09:50:15 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Luis Henriques X-Patchwork-Id: 235019 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from huckleberry.canonical.com (huckleberry.canonical.com [91.189.94.19]) by ozlabs.org (Postfix) with ESMTP id DFD922C00CB for ; Tue, 9 Apr 2013 19:44:58 +1000 (EST) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1UPV6g-0005x0-23; Tue, 09 Apr 2013 09:44:50 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1UP8kF-000621-LQ for kernel-team@lists.ubuntu.com; Mon, 08 Apr 2013 09:52:11 +0000 Received: from bl15-144-85.dsl.telepac.pt ([188.80.144.85] helo=localhost) by youngberry.canonical.com with esmtpsa (TLS1.0:DHE_RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1UP8kF-00060g-Bm; Mon, 08 Apr 2013 09:52:11 +0000 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Subject: [PATCH 060/102] tcp: preserve ACK clocking in TSO Date: Mon, 8 Apr 2013 10:50:15 +0100 Message-Id: <1365414657-29191-61-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 1.8.1.2 In-Reply-To: <1365414657-29191-1-git-send-email-luis.henriques@canonical.com> References: <1365414657-29191-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.5 X-Mailman-Approved-At: Tue, 09 Apr 2013 09:44:49 +0000 Cc: Nandita Dukkipati , Eric Dumazet , Yuchung Cheng , Van Jacobson , Neal Cardwell , "David S. Miller" X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.14 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: kernel-team-bounces@lists.ubuntu.com 3.5.7.10 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet commit f4541d60a449afd40448b06496dcd510f505928e upstream. A long standing problem with TSO is the fact that tcp_tso_should_defer() rearms the deferred timer, while it should not. Current code leads to following bad bursty behavior : 20:11:24.484333 IP A > B: . 297161:316921(19760) ack 1 win 119 20:11:24.484337 IP B > A: . ack 263721 win 1117 20:11:24.485086 IP B > A: . ack 265241 win 1117 20:11:24.485925 IP B > A: . ack 266761 win 1117 20:11:24.486759 IP B > A: . ack 268281 win 1117 20:11:24.487594 IP B > A: . ack 269801 win 1117 20:11:24.488430 IP B > A: . ack 271321 win 1117 20:11:24.489267 IP B > A: . ack 272841 win 1117 20:11:24.490104 IP B > A: . ack 274361 win 1117 20:11:24.490939 IP B > A: . ack 275881 win 1117 20:11:24.491775 IP B > A: . ack 277401 win 1117 20:11:24.491784 IP A > B: . 316921:332881(15960) ack 1 win 119 20:11:24.492620 IP B > A: . ack 278921 win 1117 20:11:24.493448 IP B > A: . ack 280441 win 1117 20:11:24.494286 IP B > A: . ack 281961 win 1117 20:11:24.495122 IP B > A: . ack 283481 win 1117 20:11:24.495958 IP B > A: . ack 285001 win 1117 20:11:24.496791 IP B > A: . ack 286521 win 1117 20:11:24.497628 IP B > A: . ack 288041 win 1117 20:11:24.498459 IP B > A: . ack 289561 win 1117 20:11:24.499296 IP B > A: . ack 291081 win 1117 20:11:24.500133 IP B > A: . ack 292601 win 1117 20:11:24.500970 IP B > A: . ack 294121 win 1117 20:11:24.501388 IP B > A: . ack 295641 win 1117 20:11:24.501398 IP A > B: . 332881:351881(19000) ack 1 win 119 While the expected behavior is more like : 20:19:49.259620 IP A > B: . 197601:202161(4560) ack 1 win 119 20:19:49.260446 IP B > A: . ack 154281 win 1212 20:19:49.261282 IP B > A: . ack 155801 win 1212 20:19:49.262125 IP B > A: . ack 157321 win 1212 20:19:49.262136 IP A > B: . 202161:206721(4560) ack 1 win 119 20:19:49.262958 IP B > A: . ack 158841 win 1212 20:19:49.263795 IP B > A: . ack 160361 win 1212 20:19:49.264628 IP B > A: . ack 161881 win 1212 20:19:49.264637 IP A > B: . 206721:211281(4560) ack 1 win 119 20:19:49.265465 IP B > A: . ack 163401 win 1212 20:19:49.265886 IP B > A: . ack 164921 win 1212 20:19:49.266722 IP B > A: . ack 166441 win 1212 20:19:49.266732 IP A > B: . 211281:215841(4560) ack 1 win 119 20:19:49.267559 IP B > A: . ack 167961 win 1212 20:19:49.268394 IP B > A: . ack 169481 win 1212 20:19:49.269232 IP B > A: . ack 171001 win 1212 20:19:49.269241 IP A > B: . 215841:221161(5320) ack 1 win 119 Signed-off-by: Eric Dumazet Cc: Yuchung Cheng Cc: Van Jacobson Cc: Neal Cardwell Cc: Nandita Dukkipati Signed-off-by: David S. Miller Signed-off-by: Luis Henriques --- net/ipv4/tcp_output.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 1195760..e0cd660 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -1604,8 +1604,11 @@ static bool tcp_tso_should_defer(struct sock *sk, struct sk_buff *skb) goto send_now; } - /* Ok, it looks like it is advisable to defer. */ - tp->tso_deferred = 1 | (jiffies << 1); + /* Ok, it looks like it is advisable to defer. + * Do not rearm the timer if already set to not break TCP ACK clocking. + */ + if (!tp->tso_deferred) + tp->tso_deferred = 1 | (jiffies << 1); return true;