Merge branch 'tcp-bbr'

Neal Cardwell says:

====================
tcp: BBR congestion control algorithm

This patch series implements a new TCP congestion control algorithm:
BBR (Bottleneck Bandwidth and RTT). A paper with a detailed
description of BBR will be published in ACM Queue, September-October
2016, as "BBR: Congestion-Based Congestion Control". BBR is widely
deployed in production at Google.

The patch series starts with a set of supporting infrastructure
changes, including a few that extend the congestion control
framework. The last patch adds BBR as a TCP congestion control
module. Please see individual patches for the details.

- v3 -> v4:
 - Updated tcp_bbr.c in "tcp_bbr: add BBR congestion control"
   to use const to qualify all the constant parameters.
   Thanks to Stephen Hemminger.
 - In "tcp_bbr: add BBR congestion control", remove the bbr_rate_kbps()
   function, which had a 64-bit divide that would be problematic on some
   architectures, and just use bbr_rate_bytes_per_sec() directly.
   Thanks to Kenneth Klette Jonassen for suggesting this.
 - In "tcp: switch back to proper tcp_skb_cb size check in tcp_init()",
   switched from sizeof(skb->cb) to FIELD_SIZEOF.
   Thanks to Lance Richardson for suggesting this.
 - Updated "tcp_bbr: add BBR congestion control" commit message with
   performance data, more details about deployment at Google, and
   another reminder to use fq with BBR.
 - Updated tcp_bbr.c in "tcp_bbr: add BBR congestion control"
   to use MODULE_LICENSE("Dual BSD/GPL").

- v2 -> v3: fix another issue caught by build bots:
 - adjust rate_sample struct initialization syntax to allow gcc-4.4 to compile
   the "tcp: track data delivery rate for a TCP connection" patch; also
   adjusted some similar syntax in "tcp_bbr: add BBR congestion control"

- v1 -> v2: fix issues caught by build bots:
 - fix "tcp: export data delivery rate" to use rate64 instead of rate,
   so there is a 64-bit numerator for the do_div call
 - fix conflicting definitions for minmax caused by
   "tcp: use windowed min filter library for TCP min_rtt estimation"
   with a new commit:
   tcp: cdg: rename struct minmax in tcp_cdg.c to avoid a naming conflict
 - fix warning about the use of __packed in
   "tcp: track data delivery rate for a TCP connection",
   which involves the addition of a new commit:
   tcp: switch back to proper tcp_skb_cb size check in tcp_init()
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 47 insertions, 4 deletions

diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index c723a465125d..a17ae7b85218 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -19,6 +19,7 @@
 
 
 #include <linux/skbuff.h>
+#include <linux/win_minmax.h>
 #include <net/sock.h>
 #include <net/inet_connection_sock.h>
 #include <net/inet_timewait_sock.h>
@@ -212,7 +213,8 @@ struct tcp_sock {
 		u8 reord;    /* reordering detected */
 	} rack;
 	u16	advmss;		/* Advertised MSS			*/
-	u8	unused;
+	u8	rate_app_limited:1,  /* rate_{delivered,interval_us} limited? */
+		unused:7;
 	u8	nonagle     : 4,/* Disable Nagle algorithm?             */
 		thin_lto    : 1,/* Use linear timeouts for thin streams */
 		thin_dupack : 1,/* Fast retransmit on first dupack      */
@@ -234,9 +236,7 @@ struct tcp_sock {
 	u32	mdev_max_us;	/* maximal mdev for the last rtt period	*/
 	u32	rttvar_us;	/* smoothed mdev_max			*/
 	u32	rtt_seq;	/* sequence number to update rttvar	*/
-	struct rtt_meas {
-		u32 rtt, ts;	/* RTT in usec and sampling time in jiffies. */
-	} rtt_min[3];
+	struct  minmax rtt_min;
 
 	u32	packets_out;	/* Packets which are "in flight"	*/
 	u32	retrans_out;	/* Retransmitted packets out		*/
@@ -268,6 +268,12 @@ 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	app_limited;	/* limited until "delivered" reaches this val */
+	struct skb_mstamp first_tx_mstamp;  /* start of window send phase */
+	struct skb_mstamp delivered_mstamp; /* time we reached "delivered" */
+	u32	rate_delivered;    /* saved rate sample: packets delivered */
+	u32	rate_interval_us;  /* saved rate sample: time elapsed */
 
  	u32	rcv_wnd;	/* Current receiver window		*/
 	u32	write_seq;	/* Tail(+1) of data held in tcp send buffer */
diff --git a/include/linux/win_minmax.h b/include/linux/win_minmax.h
new file mode 100644
index 000000000000..56569604278f
--- /dev/null
+++ b/include/linux/win_minmax.h
@@ -0,0 +1,37 @@
+/**
+ * lib/minmax.c: windowed min/max tracker by Kathleen Nichols.
+ *
+ */
+#ifndef MINMAX_H
+#define MINMAX_H
+
+#include <linux/types.h>
+
+/* A single data point for our parameterized min-max tracker */
+struct minmax_sample {
+	u32	t;	/* time measurement was taken */
+	u32	v;	/* value measured */
+};
+
+/* State for the parameterized min-max tracker */
+struct minmax {
+	struct minmax_sample s[3];
+};
+
+static inline u32 minmax_get(const struct minmax *m)
+{
+	return m->s[0].v;
+}
+
+static inline u32 minmax_reset(struct minmax *m, u32 t, u32 meas)
+{
+	struct minmax_sample val = { .t = t, .v = meas };
+
+	m->s[2] = m->s[1] = m->s[0] = val;
+	return m->s[0].v;
+}
+
+u32 minmax_running_max(struct minmax *m, u32 win, u32 t, u32 meas);
+u32 minmax_running_min(struct minmax *m, u32 win, u32 t, u32 meas);
+
+#endif