Commit a11238ec authored by David S. Miller's avatar David S. Miller

Merge branch 'dctcp'

Daniel Borkmann says:

====================
net: tcp: DCTCP congestion control algorithm

This patch series adds support for the DataCenter TCP (DCTCP) congestion
control algorithm. Please see individual patches for the details.

The last patch adds DCTCP as a congestion control module, and previous
ones add needed infrastructure to extend the congestion control framework.

Joint work between Florian Westphal, Daniel Borkmann and Glenn Judd.

v3 -> v2:
 - No changes anywhere, just a resend as requested by Dave
 - Added Stephen's ACK
v1 -> v2:
 - Rebased to latest net-next
 - Addressed Eric's feedback, thanks!
  - Update stale comment wrt. DCTCP ECN usage
  - Don't call INET_ECN_xmit for every packet
 - Add dctcp ss/inetdiag support to expose internal stats to userspace
====================
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parents 53dfd501 e3118e83
DCTCP (DataCenter TCP)
----------------------
DCTCP is an enhancement to the TCP congestion control algorithm for data
center networks and leverages Explicit Congestion Notification (ECN) in
the data center network to provide multi-bit feedback to the end hosts.
To enable it on end hosts:
sysctl -w net.ipv4.tcp_congestion_control=dctcp
All switches in the data center network running DCTCP must support ECN
marking and be configured for marking when reaching defined switch buffer
thresholds. The default ECN marking threshold heuristic for DCTCP on
switches is 20 packets (30KB) at 1Gbps, and 65 packets (~100KB) at 10Gbps,
but might need further careful tweaking.
For more details, see below documents:
Paper:
The algorithm is further described in detail in the following two
SIGCOMM/SIGMETRICS papers:
i) Mohammad Alizadeh, Albert Greenberg, David A. Maltz, Jitendra Padhye,
Parveen Patel, Balaji Prabhakar, Sudipta Sengupta, and Murari Sridharan:
"Data Center TCP (DCTCP)", Data Center Networks session
Proc. ACM SIGCOMM, New Delhi, 2010.
http://simula.stanford.edu/~alizade/Site/DCTCP_files/dctcp-final.pdf
http://www.sigcomm.org/ccr/papers/2010/October/1851275.1851192
ii) Mohammad Alizadeh, Adel Javanmard, and Balaji Prabhakar:
"Analysis of DCTCP: Stability, Convergence, and Fairness"
Proc. ACM SIGMETRICS, San Jose, 2011.
http://simula.stanford.edu/~alizade/Site/DCTCP_files/dctcp_analysis-full.pdf
IETF informational draft:
http://tools.ietf.org/html/draft-bensley-tcpm-dctcp-00
DCTCP site:
http://simula.stanford.edu/~alizade/Site/DCTCP.html
......@@ -733,23 +733,6 @@ struct tcp_skb_cb {
#define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0]))
/* RFC3168 : 6.1.1 SYN packets must not have ECT/ECN bits set
*
* If we receive a SYN packet with these bits set, it means a network is
* playing bad games with TOS bits. In order to avoid possible false congestion
* notifications, we disable TCP ECN negociation.
*/
static inline void
TCP_ECN_create_request(struct request_sock *req, const struct sk_buff *skb,
struct net *net)
{
const struct tcphdr *th = tcp_hdr(skb);
if (net->ipv4.sysctl_tcp_ecn && th->ece && th->cwr &&
INET_ECN_is_not_ect(TCP_SKB_CB(skb)->ip_dsfield))
inet_rsk(req)->ecn_ok = 1;
}
/* Due to TSO, an SKB can be composed of multiple actual
* packets. To keep these tracked properly, we use this.
*/
......@@ -780,8 +763,17 @@ enum tcp_ca_event {
CA_EVENT_CWND_RESTART, /* congestion window restart */
CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */
CA_EVENT_LOSS, /* loss timeout */
CA_EVENT_FAST_ACK, /* in sequence ack */
CA_EVENT_SLOW_ACK, /* other ack */
CA_EVENT_ECN_NO_CE, /* ECT set, but not CE marked */
CA_EVENT_ECN_IS_CE, /* received CE marked IP packet */
CA_EVENT_DELAYED_ACK, /* Delayed ack is sent */
CA_EVENT_NON_DELAYED_ACK,
};
/* Information about inbound ACK, passed to cong_ops->in_ack_event() */
enum tcp_ca_ack_event_flags {
CA_ACK_SLOWPATH = (1 << 0), /* In slow path processing */
CA_ACK_WIN_UPDATE = (1 << 1), /* ACK updated window */
CA_ACK_ECE = (1 << 2), /* ECE bit is set on ack */
};
/*
......@@ -791,7 +783,10 @@ enum tcp_ca_event {
#define TCP_CA_MAX 128
#define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX)
/* Algorithm can be set on socket without CAP_NET_ADMIN privileges */
#define TCP_CONG_NON_RESTRICTED 0x1
/* Requires ECN/ECT set on all packets */
#define TCP_CONG_NEEDS_ECN 0x2
struct tcp_congestion_ops {
struct list_head list;
......@@ -810,6 +805,8 @@ struct tcp_congestion_ops {
void (*set_state)(struct sock *sk, u8 new_state);
/* call when cwnd event occurs (optional) */
void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev);
/* call when ack arrives (optional) */
void (*in_ack_event)(struct sock *sk, u32 flags);
/* new value of cwnd after loss (optional) */
u32 (*undo_cwnd)(struct sock *sk);
/* hook for packet ack accounting (optional) */
......@@ -824,6 +821,7 @@ struct tcp_congestion_ops {
int tcp_register_congestion_control(struct tcp_congestion_ops *type);
void tcp_unregister_congestion_control(struct tcp_congestion_ops *type);
void tcp_assign_congestion_control(struct sock *sk);
void tcp_init_congestion_control(struct sock *sk);
void tcp_cleanup_congestion_control(struct sock *sk);
int tcp_set_default_congestion_control(const char *name);
......@@ -835,11 +833,17 @@ int tcp_set_congestion_control(struct sock *sk, const char *name);
int tcp_slow_start(struct tcp_sock *tp, u32 acked);
void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w);
extern struct tcp_congestion_ops tcp_init_congestion_ops;
u32 tcp_reno_ssthresh(struct sock *sk);
void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 acked);
extern struct tcp_congestion_ops tcp_reno;
static inline bool tcp_ca_needs_ecn(const struct sock *sk)
{
const struct inet_connection_sock *icsk = inet_csk(sk);
return icsk->icsk_ca_ops->flags & TCP_CONG_NEEDS_ECN;
}
static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state)
{
struct inet_connection_sock *icsk = inet_csk(sk);
......@@ -857,6 +861,40 @@ static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
icsk->icsk_ca_ops->cwnd_event(sk, event);
}
/* RFC3168 : 6.1.1 SYN packets must not have ECT/ECN bits set
*
* If we receive a SYN packet with these bits set, it means a
* network is playing bad games with TOS bits. In order to
* avoid possible false congestion notifications, we disable
* TCP ECN negociation.
*
* Exception: tcp_ca wants ECN. This is required for DCTCP
* congestion control; it requires setting ECT on all packets,
* including SYN. We inverse the test in this case: If our
* local socket wants ECN, but peer only set ece/cwr (but not
* ECT in IP header) its probably a non-DCTCP aware sender.
*/
static inline void
TCP_ECN_create_request(struct request_sock *req, const struct sk_buff *skb,
const struct sock *listen_sk)
{
const struct tcphdr *th = tcp_hdr(skb);
const struct net *net = sock_net(listen_sk);
bool th_ecn = th->ece && th->cwr;
bool ect, need_ecn;
if (!th_ecn)
return;
ect = !INET_ECN_is_not_ect(TCP_SKB_CB(skb)->ip_dsfield);
need_ecn = tcp_ca_needs_ecn(listen_sk);
if (!ect && !need_ecn && net->ipv4.sysctl_tcp_ecn)
inet_rsk(req)->ecn_ok = 1;
else if (ect && need_ecn)
inet_rsk(req)->ecn_ok = 1;
}
/* These functions determine how the current flow behaves in respect of SACK
* handling. SACK is negotiated with the peer, and therefore it can vary
* between different flows.
......
......@@ -110,10 +110,10 @@ enum {
INET_DIAG_TCLASS,
INET_DIAG_SKMEMINFO,
INET_DIAG_SHUTDOWN,
INET_DIAG_DCTCPINFO,
};
#define INET_DIAG_MAX INET_DIAG_SHUTDOWN
#define INET_DIAG_MAX INET_DIAG_DCTCPINFO
/* INET_DIAG_MEM */
......@@ -133,5 +133,14 @@ struct tcpvegas_info {
__u32 tcpv_minrtt;
};
/* INET_DIAG_DCTCPINFO */
struct tcp_dctcp_info {
__u16 dctcp_enabled;
__u16 dctcp_ce_state;
__u32 dctcp_alpha;
__u32 dctcp_ab_ecn;
__u32 dctcp_ab_tot;
};
#endif /* _UAPI_INET_DIAG_H_ */
......@@ -570,6 +570,27 @@ config TCP_CONG_ILLINOIS
For further details see:
http://www.ews.uiuc.edu/~shaoliu/tcpillinois/index.html
config TCP_CONG_DCTCP
tristate "DataCenter TCP (DCTCP)"
default n
---help---
DCTCP leverages Explicit Congestion Notification (ECN) in the network to
provide multi-bit feedback to the end hosts. It is designed to provide:
- High burst tolerance (incast due to partition/aggregate),
- Low latency (short flows, queries),
- High throughput (continuous data updates, large file transfers) with
commodity, shallow-buffered switches.
All switches in the data center network running DCTCP must support
ECN marking and be configured for marking when reaching defined switch
buffer thresholds. The default ECN marking threshold heuristic for
DCTCP on switches is 20 packets (30KB) at 1Gbps, and 65 packets
(~100KB) at 10Gbps, but might need further careful tweaking.
For further details see:
http://simula.stanford.edu/~alizade/Site/DCTCP_files/dctcp-final.pdf
choice
prompt "Default TCP congestion control"
default DEFAULT_CUBIC
......@@ -598,9 +619,11 @@ choice
config DEFAULT_WESTWOOD
bool "Westwood" if TCP_CONG_WESTWOOD=y
config DEFAULT_DCTCP
bool "DCTCP" if TCP_CONG_DCTCP=y
config DEFAULT_RENO
bool "Reno"
endchoice
endif
......@@ -620,6 +643,7 @@ config DEFAULT_TCP_CONG
default "westwood" if DEFAULT_WESTWOOD
default "veno" if DEFAULT_VENO
default "reno" if DEFAULT_RENO
default "dctcp" if DEFAULT_DCTCP
default "cubic"
config TCP_MD5SIG
......
......@@ -43,6 +43,7 @@ obj-$(CONFIG_INET_UDP_DIAG) += udp_diag.o
obj-$(CONFIG_NET_TCPPROBE) += tcp_probe.o
obj-$(CONFIG_TCP_CONG_BIC) += tcp_bic.o
obj-$(CONFIG_TCP_CONG_CUBIC) += tcp_cubic.o
obj-$(CONFIG_TCP_CONG_DCTCP) += tcp_dctcp.o
obj-$(CONFIG_TCP_CONG_WESTWOOD) += tcp_westwood.o
obj-$(CONFIG_TCP_CONG_HSTCP) += tcp_highspeed.o
obj-$(CONFIG_TCP_CONG_HYBLA) += tcp_hybla.o
......
......@@ -405,7 +405,7 @@ void tcp_init_sock(struct sock *sk)
tp->reordering = sysctl_tcp_reordering;
tcp_enable_early_retrans(tp);
icsk->icsk_ca_ops = &tcp_init_congestion_ops;
tcp_assign_congestion_control(sk);
tp->tsoffset = 0;
......@@ -3258,8 +3258,6 @@ void __init tcp_init(void)
tcp_hashinfo.ehash_mask + 1, tcp_hashinfo.bhash_size);
tcp_metrics_init();
tcp_register_congestion_control(&tcp_reno);
BUG_ON(tcp_register_congestion_control(&tcp_reno) != 0);
tcp_tasklet_init();
}
......@@ -74,24 +74,34 @@ void tcp_unregister_congestion_control(struct tcp_congestion_ops *ca)
EXPORT_SYMBOL_GPL(tcp_unregister_congestion_control);
/* Assign choice of congestion control. */
void tcp_init_congestion_control(struct sock *sk)
void tcp_assign_congestion_control(struct sock *sk)
{
struct inet_connection_sock *icsk = inet_csk(sk);
struct tcp_congestion_ops *ca;
/* if no choice made yet assign the current value set as default */
if (icsk->icsk_ca_ops == &tcp_init_congestion_ops) {
rcu_read_lock();
list_for_each_entry_rcu(ca, &tcp_cong_list, list) {
if (try_module_get(ca->owner)) {
if (likely(try_module_get(ca->owner))) {
icsk->icsk_ca_ops = ca;
break;
goto out;
}
/* fallback to next available */
/* Fallback to next available. The last really
* guaranteed fallback is Reno from this list.
*/
}
out:
rcu_read_unlock();
}
/* Clear out private data before diag gets it and
* the ca has not been initialized.
*/
if (ca->get_info)
memset(icsk->icsk_ca_priv, 0, sizeof(icsk->icsk_ca_priv));
}
void tcp_init_congestion_control(struct sock *sk)
{
const struct inet_connection_sock *icsk = inet_csk(sk);
if (icsk->icsk_ca_ops->init)
icsk->icsk_ca_ops->init(sk);
......@@ -345,15 +355,3 @@ struct tcp_congestion_ops tcp_reno = {
.ssthresh = tcp_reno_ssthresh,
.cong_avoid = tcp_reno_cong_avoid,
};
/* Initial congestion control used (until SYN)
* really reno under another name so we can tell difference
* during tcp_set_default_congestion_control
*/
struct tcp_congestion_ops tcp_init_congestion_ops = {
.name = "",
.owner = THIS_MODULE,
.ssthresh = tcp_reno_ssthresh,
.cong_avoid = tcp_reno_cong_avoid,
};
EXPORT_SYMBOL_GPL(tcp_init_congestion_ops);
/* DataCenter TCP (DCTCP) congestion control.
*
* http://simula.stanford.edu/~alizade/Site/DCTCP.html
*
* This is an implementation of DCTCP over Reno, an enhancement to the
* TCP congestion control algorithm designed for data centers. DCTCP
* leverages Explicit Congestion Notification (ECN) in the network to
* provide multi-bit feedback to the end hosts. DCTCP's goal is to meet
* the following three data center transport requirements:
*
* - High burst tolerance (incast due to partition/aggregate)
* - Low latency (short flows, queries)
* - High throughput (continuous data updates, large file transfers)
* with commodity shallow buffered switches
*
* The algorithm is described in detail in the following two papers:
*
* 1) Mohammad Alizadeh, Albert Greenberg, David A. Maltz, Jitendra Padhye,
* Parveen Patel, Balaji Prabhakar, Sudipta Sengupta, and Murari Sridharan:
* "Data Center TCP (DCTCP)", Data Center Networks session
* Proc. ACM SIGCOMM, New Delhi, 2010.
* http://simula.stanford.edu/~alizade/Site/DCTCP_files/dctcp-final.pdf
*
* 2) Mohammad Alizadeh, Adel Javanmard, and Balaji Prabhakar:
* "Analysis of DCTCP: Stability, Convergence, and Fairness"
* Proc. ACM SIGMETRICS, San Jose, 2011.
* http://simula.stanford.edu/~alizade/Site/DCTCP_files/dctcp_analysis-full.pdf
*
* Initial prototype from Abdul Kabbani, Masato Yasuda and Mohammad Alizadeh.
*
* Authors:
*
* Daniel Borkmann <dborkman@redhat.com>
* Florian Westphal <fw@strlen.de>
* Glenn Judd <glenn.judd@morganstanley.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or (at
* your option) any later version.
*/
#include <linux/module.h>
#include <linux/mm.h>
#include <net/tcp.h>
#include <linux/inet_diag.h>
#define DCTCP_MAX_ALPHA 1024U
struct dctcp {
u32 acked_bytes_ecn;
u32 acked_bytes_total;
u32 prior_snd_una;
u32 prior_rcv_nxt;
u32 dctcp_alpha;
u32 next_seq;
u32 ce_state;
u32 delayed_ack_reserved;
};
static unsigned int dctcp_shift_g __read_mostly = 4; /* g = 1/2^4 */
module_param(dctcp_shift_g, uint, 0644);
MODULE_PARM_DESC(dctcp_shift_g, "parameter g for updating dctcp_alpha");
static unsigned int dctcp_alpha_on_init __read_mostly = DCTCP_MAX_ALPHA;
module_param(dctcp_alpha_on_init, uint, 0644);
MODULE_PARM_DESC(dctcp_alpha_on_init, "parameter for initial alpha value");
static unsigned int dctcp_clamp_alpha_on_loss __read_mostly;
module_param(dctcp_clamp_alpha_on_loss, uint, 0644);
MODULE_PARM_DESC(dctcp_clamp_alpha_on_loss,
"parameter for clamping alpha on loss");
static struct tcp_congestion_ops dctcp_reno;
static void dctcp_reset(const struct tcp_sock *tp, struct dctcp *ca)
{
ca->next_seq = tp->snd_nxt;
ca->acked_bytes_ecn = 0;
ca->acked_bytes_total = 0;
}
static void dctcp_init(struct sock *sk)
{
const struct tcp_sock *tp = tcp_sk(sk);
if ((tp->ecn_flags & TCP_ECN_OK) ||
(sk->sk_state == TCP_LISTEN ||
sk->sk_state == TCP_CLOSE)) {
struct dctcp *ca = inet_csk_ca(sk);
ca->prior_snd_una = tp->snd_una;
ca->prior_rcv_nxt = tp->rcv_nxt;
ca->dctcp_alpha = min(dctcp_alpha_on_init, DCTCP_MAX_ALPHA);
ca->delayed_ack_reserved = 0;
ca->ce_state = 0;
dctcp_reset(tp, ca);
return;
}
/* No ECN support? Fall back to Reno. Also need to clear
* ECT from sk since it is set during 3WHS for DCTCP.
*/
inet_csk(sk)->icsk_ca_ops = &dctcp_reno;
INET_ECN_dontxmit(sk);
}
static u32 dctcp_ssthresh(struct sock *sk)
{
const struct dctcp *ca = inet_csk_ca(sk);
struct tcp_sock *tp = tcp_sk(sk);
return max(tp->snd_cwnd - ((tp->snd_cwnd * ca->dctcp_alpha) >> 11U), 2U);
}
/* Minimal DCTP CE state machine:
*
* S: 0 <- last pkt was non-CE
* 1 <- last pkt was CE
*/
static void dctcp_ce_state_0_to_1(struct sock *sk)
{
struct dctcp *ca = inet_csk_ca(sk);
struct tcp_sock *tp = tcp_sk(sk);
/* State has changed from CE=0 to CE=1 and delayed
* ACK has not sent yet.
*/
if (!ca->ce_state && ca->delayed_ack_reserved) {
u32 tmp_rcv_nxt;
/* Save current rcv_nxt. */
tmp_rcv_nxt = tp->rcv_nxt;
/* Generate previous ack with CE=0. */
tp->ecn_flags &= ~TCP_ECN_DEMAND_CWR;
tp->rcv_nxt = ca->prior_rcv_nxt;
tcp_send_ack(sk);
/* Recover current rcv_nxt. */
tp->rcv_nxt = tmp_rcv_nxt;
}
ca->prior_rcv_nxt = tp->rcv_nxt;
ca->ce_state = 1;
tp->ecn_flags |= TCP_ECN_DEMAND_CWR;
}
static void dctcp_ce_state_1_to_0(struct sock *sk)
{
struct dctcp *ca = inet_csk_ca(sk);
struct tcp_sock *tp = tcp_sk(sk);
/* State has changed from CE=1 to CE=0 and delayed
* ACK has not sent yet.
*/
if (ca->ce_state && ca->delayed_ack_reserved) {
u32 tmp_rcv_nxt;
/* Save current rcv_nxt. */
tmp_rcv_nxt = tp->rcv_nxt;
/* Generate previous ack with CE=1. */
tp->ecn_flags |= TCP_ECN_DEMAND_CWR;
tp->rcv_nxt = ca->prior_rcv_nxt;
tcp_send_ack(sk);
/* Recover current rcv_nxt. */
tp->rcv_nxt = tmp_rcv_nxt;
}
ca->prior_rcv_nxt = tp->rcv_nxt;
ca->ce_state = 0;
tp->ecn_flags &= ~TCP_ECN_DEMAND_CWR;
}
static void dctcp_update_alpha(struct sock *sk, u32 flags)
{
const struct tcp_sock *tp = tcp_sk(sk);
struct dctcp *ca = inet_csk_ca(sk);
u32 acked_bytes = tp->snd_una - ca->prior_snd_una;
/* If ack did not advance snd_una, count dupack as MSS size.
* If ack did update window, do not count it at all.
*/
if (acked_bytes == 0 && !(flags & CA_ACK_WIN_UPDATE))
acked_bytes = inet_csk(sk)->icsk_ack.rcv_mss;
if (acked_bytes) {
ca->acked_bytes_total += acked_bytes;
ca->prior_snd_una = tp->snd_una;
if (flags & CA_ACK_ECE)
ca->acked_bytes_ecn += acked_bytes;
}
/* Expired RTT */
if (!before(tp->snd_una, ca->next_seq)) {
/* For avoiding denominator == 1. */
if (ca->acked_bytes_total == 0)
ca->acked_bytes_total = 1;
/* alpha = (1 - g) * alpha + g * F */
ca->dctcp_alpha = ca->dctcp_alpha -
(ca->dctcp_alpha >> dctcp_shift_g) +
(ca->acked_bytes_ecn << (10U - dctcp_shift_g)) /
ca->acked_bytes_total;
if (ca->dctcp_alpha > DCTCP_MAX_ALPHA)
/* Clamp dctcp_alpha to max. */
ca->dctcp_alpha = DCTCP_MAX_ALPHA;
dctcp_reset(tp, ca);
}
}
static void dctcp_state(struct sock *sk, u8 new_state)
{
if (dctcp_clamp_alpha_on_loss && new_state == TCP_CA_Loss) {
struct dctcp *ca = inet_csk_ca(sk);
/* If this extension is enabled, we clamp dctcp_alpha to
* max on packet loss; the motivation is that dctcp_alpha
* is an indicator to the extend of congestion and packet
* loss is an indicator of extreme congestion; setting
* this in practice turned out to be beneficial, and
* effectively assumes total congestion which reduces the
* window by half.
*/
ca->dctcp_alpha = DCTCP_MAX_ALPHA;
}
}
static void dctcp_update_ack_reserved(struct sock *sk, enum tcp_ca_event ev)
{
struct dctcp *ca = inet_csk_ca(sk);
switch (ev) {
case CA_EVENT_DELAYED_ACK:
if (!ca->delayed_ack_reserved)
ca->delayed_ack_reserved = 1;
break;
case CA_EVENT_NON_DELAYED_ACK:
if (ca->delayed_ack_reserved)
ca->delayed_ack_reserved = 0;
break;
default:
/* Don't care for the rest. */
break;
}
}
static void dctcp_cwnd_event(struct sock *sk, enum tcp_ca_event ev)
{
switch (ev) {
case CA_EVENT_ECN_IS_CE:
dctcp_ce_state_0_to_1(sk);
break;
case CA_EVENT_ECN_NO_CE:
dctcp_ce_state_1_to_0(sk);
break;
case CA_EVENT_DELAYED_ACK:
case CA_EVENT_NON_DELAYED_ACK:
dctcp_update_ack_reserved(sk, ev);
break;
default:
/* Don't care for the rest. */
break;
}
}
static void dctcp_get_info(struct sock *sk, u32 ext, struct sk_buff *skb)
{
const struct dctcp *ca = inet_csk_ca(sk);
/* Fill it also in case of VEGASINFO due to req struct limits.
* We can still correctly retrieve it later.
*/
if (ext & (1 << (INET_DIAG_DCTCPINFO - 1)) ||
ext & (1 << (INET_DIAG_VEGASINFO - 1))) {
struct tcp_dctcp_info info;
memset(&info, 0, sizeof(info));
if (inet_csk(sk)->icsk_ca_ops != &dctcp_reno) {
info.dctcp_enabled = 1;
info.dctcp_ce_state = (u16) ca->ce_state;
info.dctcp_alpha = ca->dctcp_alpha;
info.dctcp_ab_ecn = ca->acked_bytes_ecn;
info.dctcp_ab_tot = ca->acked_bytes_total;
}
nla_put(skb, INET_DIAG_DCTCPINFO, sizeof(info), &info);
}
}
static struct tcp_congestion_ops dctcp __read_mostly = {
.init = dctcp_init,
.in_ack_event = dctcp_update_alpha,
.cwnd_event = dctcp_cwnd_event,
.ssthresh = dctcp_ssthresh,
.cong_avoid = tcp_reno_cong_avoid,
.set_state = dctcp_state,
.get_info = dctcp_get_info,
.flags = TCP_CONG_NEEDS_ECN,
.owner = THIS_MODULE,
.name = "dctcp",
};
static struct tcp_congestion_ops dctcp_reno __read_mostly = {
.ssthresh = tcp_reno_ssthresh,
.cong_avoid = tcp_reno_cong_avoid,
.get_info = dctcp_get_info,
.owner = THIS_MODULE,
.name = "dctcp-reno",
};
static int __init dctcp_register(void)
{
BUILD_BUG_ON(sizeof(struct dctcp) > ICSK_CA_PRIV_SIZE);
return tcp_register_congestion_control(&dctcp);
}
static void __exit dctcp_unregister(void)
{
tcp_unregister_congestion_control(&dctcp);
}
module_init(dctcp_register);
module_exit(dctcp_unregister);
MODULE_AUTHOR("Daniel Borkmann <dborkman@redhat.com>");
MODULE_AUTHOR("Florian Westphal <fw@strlen.de>");
MODULE_AUTHOR("Glenn Judd <glenn.judd@morganstanley.com>");
MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("DataCenter TCP (DCTCP)");
......@@ -233,14 +233,21 @@ static inline void TCP_ECN_check_ce(struct tcp_sock *tp, const struct sk_buff *s
tcp_enter_quickack_mode((struct sock *)tp);
break;
case INET_ECN_CE:
if (tcp_ca_needs_ecn((struct sock *)tp))
tcp_ca_event((struct sock *)tp, CA_EVENT_ECN_IS_CE);
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);
tp->ecn_flags |= TCP_ECN_DEMAND_CWR;
}
/* fallinto */
tp->ecn_flags |= TCP_ECN_SEEN;
break;
default:
if (tcp_ca_needs_ecn((struct sock *)tp))
tcp_ca_event((struct sock *)tp, CA_EVENT_ECN_NO_CE);
tp->ecn_flags |= TCP_ECN_SEEN;
break;
}
}
......@@ -3362,6 +3369,14 @@ static void tcp_process_tlp_ack(struct sock *sk, u32 ack, int flag)
}
}
static inline void tcp_in_ack_event(struct sock *sk, u32 flags)
{
const struct inet_connection_sock *icsk = inet_csk(sk);
if (icsk->icsk_ca_ops->in_ack_event)
icsk->icsk_ca_ops->in_ack_event(sk, flags);
}
/* This routine deals with incoming acks, but not outgoing ones. */
static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
{
......@@ -3421,10 +3436,12 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
tp->snd_una = ack;
flag |= FLAG_WIN_UPDATE;
tcp_ca_event(sk, CA_EVENT_FAST_ACK);
tcp_in_ack_event(sk, CA_ACK_WIN_UPDATE);
NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPHPACKS);
} else {
u32 ack_ev_flags = CA_ACK_SLOWPATH;
if (ack_seq != TCP_SKB_CB(skb)->end_seq)
flag |= FLAG_DATA;
else
......@@ -3436,10 +3453,15 @@ static int tcp_ack(struct sock *sk, const struct sk_buff *skb, int flag)
flag |= tcp_sacktag_write_queue(sk, skb, prior_snd_una,
&sack_rtt_us);
if (TCP_ECN_rcv_ecn_echo(tp, tcp_hdr(skb)))
if (TCP_ECN_rcv_ecn_echo(tp, tcp_hdr(skb))) {
flag |= FLAG_ECE;
ack_ev_flags |= CA_ACK_ECE;
}
if (flag & FLAG_WIN_UPDATE)
ack_ev_flags |= CA_ACK_WIN_UPDATE;
tcp_ca_event(sk, CA_EVENT_SLOW_ACK);
tcp_in_ack_event(sk, ack_ev_flags);
}
/* We passed data and got it acked, remove any soft error
......@@ -5944,7 +5966,7 @@ int tcp_conn_request(struct request_sock_ops *rsk_ops,
goto drop_and_free;
if (!want_cookie || tmp_opt.tstamp_ok)
TCP_ECN_create_request(req, skb, sock_net(sk));
TCP_ECN_create_request(req, skb, sk);
if (want_cookie) {
isn = cookie_init_sequence(af_ops, sk, skb, &req->mss);
......
......@@ -451,9 +451,8 @@ struct sock *tcp_create_openreq_child(struct sock *sk, struct request_sock *req,
newtp->snd_cwnd = TCP_INIT_CWND;
newtp->snd_cwnd_cnt = 0;
if (newicsk->icsk_ca_ops != &tcp_init_congestion_ops &&
!try_module_get(newicsk->icsk_ca_ops->owner))
newicsk->icsk_ca_ops = &tcp_init_congestion_ops;
if (!try_module_get(newicsk->icsk_ca_ops->owner))
tcp_assign_congestion_control(newsk);
tcp_set_ca_state(newsk, TCP_CA_Open);
tcp_init_xmit_timers(newsk);
......
......@@ -318,11 +318,15 @@ static u16 tcp_select_window(struct sock *sk)
}
/* Packet ECN state for a SYN-ACK */
static inline void TCP_ECN_send_synack(const struct tcp_sock *tp, struct sk_buff *skb)
static inline void TCP_ECN_send_synack(struct sock *sk, struct sk_buff *skb)
{
const struct tcp_sock *tp = tcp_sk(sk);
TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_CWR;
if (!(tp->ecn_flags & TCP_ECN_OK))
TCP_SKB_CB(skb)->tcp_flags &= ~TCPHDR_ECE;
else if (tcp_ca_needs_ecn(sk))
INET_ECN_xmit(sk);
}
/* Packet ECN state for a SYN. */
......@@ -331,17 +335,24 @@ static inline void TCP_ECN_send_syn(struct sock *sk, struct sk_buff *skb)
struct tcp_sock *tp = tcp_sk(sk);
tp->ecn_flags = 0;
if (sock_net(sk)->ipv4.sysctl_tcp_ecn == 1) {
if (sock_net(sk)->ipv4.sysctl_tcp_ecn == 1 ||
tcp_ca_needs_ecn(sk)) {
TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_ECE | TCPHDR_CWR;
tp->ecn_flags = TCP_ECN_OK;
if (tcp_ca_needs_ecn(sk))
INET_ECN_xmit(sk);
}
}
static __inline__ void
TCP_ECN_make_synack(const struct request_sock *req, struct tcphdr *th)
TCP_ECN_make_synack(const struct request_sock *req, struct tcphdr *th,
struct sock *sk)
{
if (inet_rsk(req)->ecn_ok)
if (inet_rsk(req)->ecn_ok) {
th->ece = 1;
if (tcp_ca_needs_ecn(sk))
INET_ECN_xmit(sk);
}
}
/* Set up ECN state for a packet on a ESTABLISHED socket that is about to
......@@ -362,7 +373,7 @@ static inline void TCP_ECN_send(struct sock *sk, struct sk_buff *skb,
tcp_hdr(skb)->cwr = 1;
skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ECN;
}
} else {
} else if (!tcp_ca_needs_ecn(sk)) {
/* ACK or retransmitted segment: clear ECT|CE */
INET_ECN_dontxmit(sk);
}
......@@ -2789,7 +2800,7 @@ int tcp_send_synack(struct sock *sk)
}
TCP_SKB_CB(skb)->tcp_flags |= TCPHDR_ACK;
TCP_ECN_send_synack(tcp_sk(sk), skb);
TCP_ECN_send_synack(sk, skb);
}
return tcp_transmit_skb(sk, skb, 1, GFP_ATOMIC);
}
......@@ -2848,7 +2859,7 @@ struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst,
memset(th, 0, sizeof(struct tcphdr));
th->syn = 1;
th->ack = 1;
TCP_ECN_make_synack(req, th);
TCP_ECN_make_synack(req, th, sk);
th->source = htons(ireq->ir_num);
th->dest = ireq->ir_rmt_port;
/* Setting of flags are superfluous here for callers (and ECE is
......@@ -3119,6 +3130,8 @@ void tcp_send_delayed_ack(struct sock *sk)
int ato = icsk->icsk_ack.ato;
unsigned long timeout;
tcp_ca_event(sk, CA_EVENT_DELAYED_ACK);
if (ato > TCP_DELACK_MIN) {
const struct tcp_sock *tp = tcp_sk(sk);
int max_ato = HZ / 2;
......@@ -3175,6 +3188,8 @@ void tcp_send_ack(struct sock *sk)
if (sk->sk_state == TCP_CLOSE)
return;
tcp_ca_event(sk, CA_EVENT_NON_DELAYED_ACK);
/* We are not putting this on the write queue, so
* tcp_transmit_skb() will set the ownership to this
* sock.
......@@ -3196,6 +3211,7 @@ void tcp_send_ack(struct sock *sk)
skb_mstamp_get(&buff->skb_mstamp);
tcp_transmit_skb(sk, buff, 0, sk_gfp_atomic(sk, GFP_ATOMIC));
}
EXPORT_SYMBOL_GPL(tcp_send_ack);
/* This routine sends a packet with an out of date sequence
* number. It assumes the other end will try to ack it.
......
......@@ -220,32 +220,35 @@ static u32 tcp_westwood_bw_rttmin(const struct sock *sk)
return max_t(u32, (w->bw_est * w->rtt_min) / tp->mss_cache, 2);
}
static void tcp_westwood_ack(struct sock *sk, u32 ack_flags)
{
if (ack_flags & CA_ACK_SLOWPATH) {
struct westwood *w = inet_csk_ca(sk);
westwood_update_window(sk);
w->bk += westwood_acked_count(sk);
update_rtt_min(w);
return;
}
westwood_fast_bw(sk);
}
static void tcp_westwood_event(struct sock *sk, enum tcp_ca_event event)
{
struct tcp_sock *tp = tcp_sk(sk);
struct westwood *w = inet_csk_ca(sk);
switch (event) {
case CA_EVENT_FAST_ACK:
westwood_fast_bw(sk);
break;
case CA_EVENT_COMPLETE_CWR:
tp->snd_cwnd = tp->snd_ssthresh = tcp_westwood_bw_rttmin(sk);
break;
case CA_EVENT_LOSS:
tp->snd_ssthresh = tcp_westwood_bw_rttmin(sk);
/* Update RTT_min when next ack arrives */
w->reset_rtt_min = 1;
break;
case CA_EVENT_SLOW_ACK:
westwood_update_window(sk);
w->bk += westwood_acked_count(sk);
update_rtt_min(w);
break;
default:
/* don't care */
break;
......@@ -274,6 +277,7 @@ static struct tcp_congestion_ops tcp_westwood __read_mostly = {
.ssthresh = tcp_reno_ssthresh,
.cong_avoid = tcp_reno_cong_avoid,
.cwnd_event = tcp_westwood_event,
.in_ack_event = tcp_westwood_ack,
.get_info = tcp_westwood_info,
.pkts_acked = tcp_westwood_pkts_acked,
......
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