From patchwork Sun Sep 18 22:03:43 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Neal Cardwell X-Patchwork-Id: 671489 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 3scjjX6hD1z9t2Y for ; Mon, 19 Sep 2016 08:04:32 +1000 (AEST) Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=google.com header.i=@google.com header.b=a/S9aumG; dkim-atps=neutral Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936414AbcIRWE2 (ORCPT ); Sun, 18 Sep 2016 18:04:28 -0400 Received: from mail-qt0-f172.google.com ([209.85.216.172]:35958 "EHLO mail-qt0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934785AbcIRWEO (ORCPT ); Sun, 18 Sep 2016 18:04:14 -0400 Received: by mail-qt0-f172.google.com with SMTP id l91so64342107qte.3 for ; Sun, 18 Sep 2016 15:04:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20120113; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=zXfcn9O1ry/Cz4YUbaAQiIeyruh/VCDa0Hx4jGK5IPY=; b=a/S9aumGF2+zkC+C5My357qjeovzGN4+Up4n8UNU+lOmnBNHF99BNPX64ON8vPZxO1 jIY/BHMqv718FVcEAcZl1Sml7KP81oLktAVnJohF2v3XK2rtTWTzXA0aeJnChN+Ro5ml wgmvyhrBDCUcDQthsL563K90X4BrPIevbslZUJQfuxrEPQNpq7B8LtmEPB+ztNUHafqK hXDWZqYiy39uKNcW1Di3mxsDfx8LLLnYzdCjoknuB9DF51ysvhyR+68SE+9M0JZgBUmp zOjekNWzWKrSLuVI3OH8kng9BcsmKhqQ8DlF9d5zl8n05yLVYBIp8OSknTeRWCs4ppB6 FUAg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=zXfcn9O1ry/Cz4YUbaAQiIeyruh/VCDa0Hx4jGK5IPY=; b=gofb0obPsnpLcVZiKC3jx+g4UfvFqtmqqglmSxljAdZ9q7gC6wi7IyocpoGxjCv9/F Km0KYz/b5bGK8+Fs7fThB15J8ptKS7a6ZSy0p7BcsAD+I1SunXKUnYqhzZvUoXiuI8Ky fWgwRmGhzrrI0L5pJ+CFItvtDKsAx0AtOBJSfHYtZfW6euna1i/qFa/4yilxemxf5Q3V cb0hL2QDvrZFxmtWzVneyblJzkVOXHYONBxLOBfFLMU221UNMYwyO15oFFKywXID8tgG RkMijKHnaV7M5rGlxIyAo6LhudP7arpLhR/rv5mGFhr8g2m7b91ivbAPN89ue3tQs+sd Id2g== X-Gm-Message-State: AE9vXwNxY+YgTzTSATZdifCQJEoABP3JBndhJUzSi56Jrs19dswHr+A1gifRUd6c95kguLOc X-Received: by 10.200.45.220 with SMTP id q28mr26924767qta.108.1474236252928; Sun, 18 Sep 2016 15:04:12 -0700 (PDT) Received: from joy.nyc.corp.google.com ([100.101.230.104]) by smtp.gmail.com with ESMTPSA id v43sm11313014qtv.15.2016.09.18.15.04.12 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Sun, 18 Sep 2016 15:04:12 -0700 (PDT) From: Neal Cardwell To: David Miller Cc: netdev@vger.kernel.org, Neal Cardwell , Van Jacobson , Yuchung Cheng , Nandita Dukkipati , Eric Dumazet , Soheil Hassas Yeganeh Subject: [PATCH v3 net-next 06/16] tcp: count packets marked lost for a TCP connection Date: Sun, 18 Sep 2016 18:03:43 -0400 Message-Id: <1474236233-28511-7-git-send-email-ncardwell@google.com> X-Mailer: git-send-email 2.8.0.rc3.226.g39d4020 In-Reply-To: <1474236233-28511-1-git-send-email-ncardwell@google.com> References: <1474236233-28511-1-git-send-email-ncardwell@google.com> Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Count the number of packets that a TCP connection marks lost. Congestion control modules can use this loss rate information for more intelligent decisions about how fast to send. Specifically, this is used in TCP BBR policer detection. BBR uses a high packet loss rate as one signal in its policer detection and policer bandwidth estimation algorithm. The BBR policer detection algorithm cannot simply track retransmits, because a retransmit can be (and often is) an indicator of packets lost long, long ago. This is particularly true in a long CA_Loss period that repairs the initial massive losses when a policer kicks in. Signed-off-by: Van Jacobson Signed-off-by: Neal Cardwell Signed-off-by: Yuchung Cheng Signed-off-by: Nandita Dukkipati Signed-off-by: Eric Dumazet Signed-off-by: Soheil Hassas Yeganeh --- include/linux/tcp.h | 1 + net/ipv4/tcp_input.c | 25 ++++++++++++++++++++++++- 2 files changed, 25 insertions(+), 1 deletion(-) diff --git a/include/linux/tcp.h b/include/linux/tcp.h index 6433cc8..38590fb 100644 --- a/include/linux/tcp.h +++ b/include/linux/tcp.h @@ -267,6 +267,7 @@ struct tcp_sock { * receiver in Recovery. */ u32 prr_out; /* Total number of pkts sent during Recovery. */ u32 delivered; /* Total data packets delivered incl. rexmits */ + u32 lost; /* Total data packets lost incl. rexmits */ u32 rcv_wnd; /* Current receiver window */ u32 write_seq; /* Tail(+1) of data held in tcp send buffer */ diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index ac5b38f..024b579 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -899,12 +899,29 @@ static void tcp_verify_retransmit_hint(struct tcp_sock *tp, struct sk_buff *skb) tp->retransmit_high = TCP_SKB_CB(skb)->end_seq; } +/* Sum the number of packets on the wire we have marked as lost. + * There are two cases we care about here: + * a) Packet hasn't been marked lost (nor retransmitted), + * and this is the first loss. + * b) Packet has been marked both lost and retransmitted, + * and this means we think it was lost again. + */ +static void tcp_sum_lost(struct tcp_sock *tp, struct sk_buff *skb) +{ + __u8 sacked = TCP_SKB_CB(skb)->sacked; + + if (!(sacked & TCPCB_LOST) || + ((sacked & TCPCB_LOST) && (sacked & TCPCB_SACKED_RETRANS))) + tp->lost += tcp_skb_pcount(skb); +} + static void tcp_skb_mark_lost(struct tcp_sock *tp, struct sk_buff *skb) { if (!(TCP_SKB_CB(skb)->sacked & (TCPCB_LOST|TCPCB_SACKED_ACKED))) { tcp_verify_retransmit_hint(tp, skb); tp->lost_out += tcp_skb_pcount(skb); + tcp_sum_lost(tp, skb); TCP_SKB_CB(skb)->sacked |= TCPCB_LOST; } } @@ -913,6 +930,7 @@ void tcp_skb_mark_lost_uncond_verify(struct tcp_sock *tp, struct sk_buff *skb) { tcp_verify_retransmit_hint(tp, skb); + tcp_sum_lost(tp, skb); if (!(TCP_SKB_CB(skb)->sacked & (TCPCB_LOST|TCPCB_SACKED_ACKED))) { tp->lost_out += tcp_skb_pcount(skb); TCP_SKB_CB(skb)->sacked |= TCPCB_LOST; @@ -1890,6 +1908,7 @@ void tcp_enter_loss(struct sock *sk) struct sk_buff *skb; bool new_recovery = icsk->icsk_ca_state < TCP_CA_Recovery; bool is_reneg; /* is receiver reneging on SACKs? */ + bool mark_lost; /* Reduce ssthresh if it has not yet been made inside this window. */ if (icsk->icsk_ca_state <= TCP_CA_Disorder || @@ -1923,8 +1942,12 @@ void tcp_enter_loss(struct sock *sk) if (skb == tcp_send_head(sk)) break; + mark_lost = (!(TCP_SKB_CB(skb)->sacked & TCPCB_SACKED_ACKED) || + is_reneg); + if (mark_lost) + tcp_sum_lost(tp, skb); TCP_SKB_CB(skb)->sacked &= (~TCPCB_TAGBITS)|TCPCB_SACKED_ACKED; - if (!(TCP_SKB_CB(skb)->sacked&TCPCB_SACKED_ACKED) || is_reneg) { + if (mark_lost) { TCP_SKB_CB(skb)->sacked &= ~TCPCB_SACKED_ACKED; TCP_SKB_CB(skb)->sacked |= TCPCB_LOST; tp->lost_out += tcp_skb_pcount(skb);