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linux-stable/include/uapi/linux/tcp.h
Eric Dumazet a842fe1425 tcp: add optional per socket transmit delay 
Adding delays to TCP flows is crucial for studying behavior
of TCP stacks, including congestion control modules.

Linux offers netem module, but it has unpractical constraints :
- Need root access to change qdisc
- Hard to setup on egress if combined with non trivial qdisc like FQ
- Single delay for all flows.

EDT (Earliest Departure Time) adoption in TCP stack allows us
to enable a per socket delay at a very small cost.

Networking tools can now establish thousands of flows, each of them
with a different delay, simulating real world conditions.

This requires FQ packet scheduler or a EDT-enabled NIC.

This patchs adds TCP_TX_DELAY socket option, to set a delay in
usec units.

  unsigned int tx_delay = 10000; /* 10 msec */

  setsockopt(fd, SOL_TCP, TCP_TX_DELAY, &tx_delay, sizeof(tx_delay));

Note that FQ packet scheduler limits might need some tweaking :

man tc-fq

PARAMETERS
   limit
       Hard  limit  on  the  real  queue  size. When this limit is
       reached, new packets are dropped. If the value is  lowered,
       packets  are  dropped so that the new limit is met. Default
       is 10000 packets.

   flow_limit
       Hard limit on the maximum  number  of  packets  queued  per
       flow.  Default value is 100.

Use of TCP_TX_DELAY option will increase number of skbs in FQ qdisc,
so packets would be dropped if any of the previous limit is hit.

Use of a jump label makes this support runtime-free, for hosts
never using the option.

Also note that TSQ (TCP Small Queues) limits are slightly changed
with this patch : we need to account that skbs artificially delayed
wont stop us providind more skbs to feed the pipe (netem uses
skb_orphan_partial() for this purpose, but FQ can not use this trick)

Because of that, using big delays might very well trigger
old bugs in TSO auto defer logic and/or sndbuf limited detection.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2019-06-12 13:05:43 -07:00

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/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */
/*
* INET An implementation of the TCP/IP protocol suite for the LINUX
* operating system. INET is implemented using the BSD Socket
* interface as the means of communication with the user level.
*
* Definitions for the TCP protocol.
*
* Version: @(#)tcp.h 1.0.2 04/28/93
*
* Author: Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
*
* 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.
*/
#ifndef _UAPI_LINUX_TCP_H
#define _UAPI_LINUX_TCP_H
#include <linux/types.h>
#include <asm/byteorder.h>
#include <linux/socket.h>
struct tcphdr {
__be16 source;
__be16 dest;
__be32 seq;
__be32 ack_seq;
#if defined(__LITTLE_ENDIAN_BITFIELD)
__u16 res1:4,
doff:4,
fin:1,
syn:1,
rst:1,
psh:1,
ack:1,
urg:1,
ece:1,
cwr:1;
#elif defined(__BIG_ENDIAN_BITFIELD)
__u16 doff:4,
res1:4,
cwr:1,
ece:1,
urg:1,
ack:1,
psh:1,
rst:1,
syn:1,
fin:1;
#else
#error "Adjust your <asm/byteorder.h> defines"
#endif
__be16 window;
__sum16 check;
__be16 urg_ptr;
};
/*
* The union cast uses a gcc extension to avoid aliasing problems
* (union is compatible to any of its members)
* This means this part of the code is -fstrict-aliasing safe now.
*/
union tcp_word_hdr {
struct tcphdr hdr;
__be32 words[5];
};
#define tcp_flag_word(tp) ( ((union tcp_word_hdr *)(tp))->words [3])
enum {
TCP_FLAG_CWR = __constant_cpu_to_be32(0x00800000),
TCP_FLAG_ECE = __constant_cpu_to_be32(0x00400000),
TCP_FLAG_URG = __constant_cpu_to_be32(0x00200000),
TCP_FLAG_ACK = __constant_cpu_to_be32(0x00100000),
TCP_FLAG_PSH = __constant_cpu_to_be32(0x00080000),
TCP_FLAG_RST = __constant_cpu_to_be32(0x00040000),
TCP_FLAG_SYN = __constant_cpu_to_be32(0x00020000),
TCP_FLAG_FIN = __constant_cpu_to_be32(0x00010000),
TCP_RESERVED_BITS = __constant_cpu_to_be32(0x0F000000),
TCP_DATA_OFFSET = __constant_cpu_to_be32(0xF0000000)
};
/*
* TCP general constants
*/
#define TCP_MSS_DEFAULT 536U /* IPv4 (RFC1122, RFC2581) */
#define TCP_MSS_DESIRED 1220U /* IPv6 (tunneled), EDNS0 (RFC3226) */
/* TCP socket options */
#define TCP_NODELAY 1 /* Turn off Nagle's algorithm. */
#define TCP_MAXSEG 2 /* Limit MSS */
#define TCP_CORK 3 /* Never send partially complete segments */
#define TCP_KEEPIDLE 4 /* Start keeplives after this period */
#define TCP_KEEPINTVL 5 /* Interval between keepalives */
#define TCP_KEEPCNT 6 /* Number of keepalives before death */
#define TCP_SYNCNT 7 /* Number of SYN retransmits */
#define TCP_LINGER2 8 /* Life time of orphaned FIN-WAIT-2 state */
#define TCP_DEFER_ACCEPT 9 /* Wake up listener only when data arrive */
#define TCP_WINDOW_CLAMP 10 /* Bound advertised window */
#define TCP_INFO 11 /* Information about this connection. */
#define TCP_QUICKACK 12 /* Block/reenable quick acks */
#define TCP_CONGESTION 13 /* Congestion control algorithm */
#define TCP_MD5SIG 14 /* TCP MD5 Signature (RFC2385) */
#define TCP_THIN_LINEAR_TIMEOUTS 16 /* Use linear timeouts for thin streams*/
#define TCP_THIN_DUPACK 17 /* Fast retrans. after 1 dupack */
#define TCP_USER_TIMEOUT 18 /* How long for loss retry before timeout */
#define TCP_REPAIR 19 /* TCP sock is under repair right now */
#define TCP_REPAIR_QUEUE 20
#define TCP_QUEUE_SEQ 21
#define TCP_REPAIR_OPTIONS 22
#define TCP_FASTOPEN 23 /* Enable FastOpen on listeners */
#define TCP_TIMESTAMP 24
#define TCP_NOTSENT_LOWAT 25 /* limit number of unsent bytes in write queue */
#define TCP_CC_INFO 26 /* Get Congestion Control (optional) info */
#define TCP_SAVE_SYN 27 /* Record SYN headers for new connections */
#define TCP_SAVED_SYN 28 /* Get SYN headers recorded for connection */
#define TCP_REPAIR_WINDOW 29 /* Get/set window parameters */
#define TCP_FASTOPEN_CONNECT 30 /* Attempt FastOpen with connect */
#define TCP_ULP 31 /* Attach a ULP to a TCP connection */
#define TCP_MD5SIG_EXT 32 /* TCP MD5 Signature with extensions */
#define TCP_FASTOPEN_KEY 33 /* Set the key for Fast Open (cookie) */
#define TCP_FASTOPEN_NO_COOKIE 34 /* Enable TFO without a TFO cookie */
#define TCP_ZEROCOPY_RECEIVE 35
#define TCP_INQ 36 /* Notify bytes available to read as a cmsg on read */
#define TCP_CM_INQ TCP_INQ
#define TCP_TX_DELAY 37 /* delay outgoing packets by XX usec */
#define TCP_REPAIR_ON 1
#define TCP_REPAIR_OFF 0
#define TCP_REPAIR_OFF_NO_WP -1 /* Turn off without window probes */
struct tcp_repair_opt {
__u32 opt_code;
__u32 opt_val;
};
struct tcp_repair_window {
__u32 snd_wl1;
__u32 snd_wnd;
__u32 max_window;
__u32 rcv_wnd;
__u32 rcv_wup;
};
enum {
TCP_NO_QUEUE,
TCP_RECV_QUEUE,
TCP_SEND_QUEUE,
TCP_QUEUES_NR,
};
/* for TCP_INFO socket option */
#define TCPI_OPT_TIMESTAMPS 1
#define TCPI_OPT_SACK 2
#define TCPI_OPT_WSCALE 4
#define TCPI_OPT_ECN 8 /* ECN was negociated at TCP session init */
#define TCPI_OPT_ECN_SEEN 16 /* we received at least one packet with ECT */
#define TCPI_OPT_SYN_DATA 32 /* SYN-ACK acked data in SYN sent or rcvd */
/*
* Sender's congestion state indicating normal or abnormal situations
* in the last round of packets sent. The state is driven by the ACK
* information and timer events.
*/
enum tcp_ca_state {
/*
* Nothing bad has been observed recently.
* No apparent reordering, packet loss, or ECN marks.
*/
TCP_CA_Open = 0,
#define TCPF_CA_Open (1<<TCP_CA_Open)
/*
* The sender enters disordered state when it has received DUPACKs or
* SACKs in the last round of packets sent. This could be due to packet
* loss or reordering but needs further information to confirm packets
* have been lost.
*/
TCP_CA_Disorder = 1,
#define TCPF_CA_Disorder (1<<TCP_CA_Disorder)
/*
* The sender enters Congestion Window Reduction (CWR) state when it
* has received ACKs with ECN-ECE marks, or has experienced congestion
* or packet discard on the sender host (e.g. qdisc).
*/
TCP_CA_CWR = 2,
#define TCPF_CA_CWR (1<<TCP_CA_CWR)
/*
* The sender is in fast recovery and retransmitting lost packets,
* typically triggered by ACK events.
*/
TCP_CA_Recovery = 3,
#define TCPF_CA_Recovery (1<<TCP_CA_Recovery)
/*
* The sender is in loss recovery triggered by retransmission timeout.
*/
TCP_CA_Loss = 4
#define TCPF_CA_Loss (1<<TCP_CA_Loss)
};
struct tcp_info {
__u8 tcpi_state;
__u8 tcpi_ca_state;
__u8 tcpi_retransmits;
__u8 tcpi_probes;
__u8 tcpi_backoff;
__u8 tcpi_options;
__u8 tcpi_snd_wscale : 4, tcpi_rcv_wscale : 4;
__u8 tcpi_delivery_rate_app_limited:1;
__u32 tcpi_rto;
__u32 tcpi_ato;
__u32 tcpi_snd_mss;
__u32 tcpi_rcv_mss;
__u32 tcpi_unacked;
__u32 tcpi_sacked;
__u32 tcpi_lost;
__u32 tcpi_retrans;
__u32 tcpi_fackets;
/* Times. */
__u32 tcpi_last_data_sent;
__u32 tcpi_last_ack_sent; /* Not remembered, sorry. */
__u32 tcpi_last_data_recv;
__u32 tcpi_last_ack_recv;
/* Metrics. */
__u32 tcpi_pmtu;
__u32 tcpi_rcv_ssthresh;
__u32 tcpi_rtt;
__u32 tcpi_rttvar;
__u32 tcpi_snd_ssthresh;
__u32 tcpi_snd_cwnd;
__u32 tcpi_advmss;
__u32 tcpi_reordering;
__u32 tcpi_rcv_rtt;
__u32 tcpi_rcv_space;
__u32 tcpi_total_retrans;
__u64 tcpi_pacing_rate;
__u64 tcpi_max_pacing_rate;
__u64 tcpi_bytes_acked; /* RFC4898 tcpEStatsAppHCThruOctetsAcked */
__u64 tcpi_bytes_received; /* RFC4898 tcpEStatsAppHCThruOctetsReceived */
__u32 tcpi_segs_out; /* RFC4898 tcpEStatsPerfSegsOut */
__u32 tcpi_segs_in; /* RFC4898 tcpEStatsPerfSegsIn */
__u32 tcpi_notsent_bytes;
__u32 tcpi_min_rtt;
__u32 tcpi_data_segs_in; /* RFC4898 tcpEStatsDataSegsIn */
__u32 tcpi_data_segs_out; /* RFC4898 tcpEStatsDataSegsOut */
__u64 tcpi_delivery_rate;
__u64 tcpi_busy_time; /* Time (usec) busy sending data */
__u64 tcpi_rwnd_limited; /* Time (usec) limited by receive window */
__u64 tcpi_sndbuf_limited; /* Time (usec) limited by send buffer */
__u32 tcpi_delivered;
__u32 tcpi_delivered_ce;
__u64 tcpi_bytes_sent; /* RFC4898 tcpEStatsPerfHCDataOctetsOut */
__u64 tcpi_bytes_retrans; /* RFC4898 tcpEStatsPerfOctetsRetrans */
__u32 tcpi_dsack_dups; /* RFC4898 tcpEStatsStackDSACKDups */
__u32 tcpi_reord_seen; /* reordering events seen */
};
/* netlink attributes types for SCM_TIMESTAMPING_OPT_STATS */
enum {
TCP_NLA_PAD,
TCP_NLA_BUSY, /* Time (usec) busy sending data */
TCP_NLA_RWND_LIMITED, /* Time (usec) limited by receive window */
TCP_NLA_SNDBUF_LIMITED, /* Time (usec) limited by send buffer */
TCP_NLA_DATA_SEGS_OUT, /* Data pkts sent including retransmission */
TCP_NLA_TOTAL_RETRANS, /* Data pkts retransmitted */
TCP_NLA_PACING_RATE, /* Pacing rate in bytes per second */
TCP_NLA_DELIVERY_RATE, /* Delivery rate in bytes per second */
TCP_NLA_SND_CWND, /* Sending congestion window */
TCP_NLA_REORDERING, /* Reordering metric */
TCP_NLA_MIN_RTT, /* minimum RTT */
TCP_NLA_RECUR_RETRANS, /* Recurring retransmits for the current pkt */
TCP_NLA_DELIVERY_RATE_APP_LMT, /* delivery rate application limited ? */
TCP_NLA_SNDQ_SIZE, /* Data (bytes) pending in send queue */
TCP_NLA_CA_STATE, /* ca_state of socket */
TCP_NLA_SND_SSTHRESH, /* Slow start size threshold */
TCP_NLA_DELIVERED, /* Data pkts delivered incl. out-of-order */
TCP_NLA_DELIVERED_CE, /* Like above but only ones w/ CE marks */
TCP_NLA_BYTES_SENT, /* Data bytes sent including retransmission */
TCP_NLA_BYTES_RETRANS, /* Data bytes retransmitted */
TCP_NLA_DSACK_DUPS, /* DSACK blocks received */
TCP_NLA_REORD_SEEN, /* reordering events seen */
TCP_NLA_SRTT, /* smoothed RTT in usecs */
};
/* for TCP_MD5SIG socket option */
#define TCP_MD5SIG_MAXKEYLEN 80
/* tcp_md5sig extension flags for TCP_MD5SIG_EXT */
#define TCP_MD5SIG_FLAG_PREFIX 1 /* address prefix length */
struct tcp_md5sig {
struct __kernel_sockaddr_storage tcpm_addr; /* address associated */
__u8 tcpm_flags; /* extension flags */
__u8 tcpm_prefixlen; /* address prefix */
__u16 tcpm_keylen; /* key length */
__u32 __tcpm_pad; /* zero */
__u8 tcpm_key[TCP_MD5SIG_MAXKEYLEN]; /* key (binary) */
};
/* INET_DIAG_MD5SIG */
struct tcp_diag_md5sig {
__u8 tcpm_family;
__u8 tcpm_prefixlen;
__u16 tcpm_keylen;
__be32 tcpm_addr[4];
__u8 tcpm_key[TCP_MD5SIG_MAXKEYLEN];
};
/* setsockopt(fd, IPPROTO_TCP, TCP_ZEROCOPY_RECEIVE, ...) */
struct tcp_zerocopy_receive {
__u64 address; /* in: address of mapping */
__u32 length; /* in/out: number of bytes to map/mapped */
__u32 recv_skip_hint; /* out: amount of bytes to skip */
};
#endif /* _UAPI_LINUX_TCP_H */
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