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linux-next/include/uapi/linux/tcp_metrics.h
Eric Dumazet 740b0f1841 tcp: switch rtt estimations to usec resolution
Upcoming congestion controls for TCP require usec resolution for RTT
estimations. Millisecond resolution is simply not enough these days.

FQ/pacing in DC environments also require this change for finer control
and removal of bimodal behavior due to the current hack in
tcp_update_pacing_rate() for 'small rtt'

TCP_CONG_RTT_STAMP is no longer needed.

As Julian Anastasov pointed out, we need to keep user compatibility :
tcp_metrics used to export RTT and RTTVAR in msec resolution,
so we added RTT_US and RTTVAR_US. An iproute2 patch is needed
to use the new attributes if provided by the kernel.

In this example ss command displays a srtt of 32 usecs (10Gbit link)

lpk51:~# ./ss -i dst lpk52
Netid  State      Recv-Q Send-Q   Local Address:Port       Peer
Address:Port
tcp    ESTAB      0      1         10.246.11.51:42959
10.246.11.52:64614
         cubic wscale:6,6 rto:201 rtt:0.032/0.001 ato:40 mss:1448
cwnd:10 send
3620.0Mbps pacing_rate 7240.0Mbps unacked:1 rcv_rtt:993 rcv_space:29559

Updated iproute2 ip command displays :

lpk51:~# ./ip tcp_metrics | grep 10.246.11.52
10.246.11.52 age 561.914sec cwnd 10 rtt 274us rttvar 213us source
10.246.11.51

Old binary displays :

lpk51:~# ip tcp_metrics | grep 10.246.11.52
10.246.11.52 age 561.914sec cwnd 10 rtt 250us rttvar 125us source
10.246.11.51

With help from Julian Anastasov, Stephen Hemminger and Yuchung Cheng

Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Cc: Stephen Hemminger <stephen@networkplumber.org>
Cc: Yuchung Cheng <ycheng@google.com>
Cc: Larry Brakmo <brakmo@google.com>
Cc: Julian Anastasov <ja@ssi.bg>
Signed-off-by: David S. Miller <davem@davemloft.net>
2014-02-26 17:08:40 -05:00

60 lines
1.4 KiB
C

/* tcp_metrics.h - TCP Metrics Interface */
#ifndef _LINUX_TCP_METRICS_H
#define _LINUX_TCP_METRICS_H
#include <linux/types.h>
/* NETLINK_GENERIC related info
*/
#define TCP_METRICS_GENL_NAME "tcp_metrics"
#define TCP_METRICS_GENL_VERSION 0x1
enum tcp_metric_index {
TCP_METRIC_RTT, /* in ms units */
TCP_METRIC_RTTVAR, /* in ms units */
TCP_METRIC_SSTHRESH,
TCP_METRIC_CWND,
TCP_METRIC_REORDERING,
TCP_METRIC_RTT_US, /* in usec units */
TCP_METRIC_RTTVAR_US, /* in usec units */
/* Always last. */
__TCP_METRIC_MAX,
};
#define TCP_METRIC_MAX (__TCP_METRIC_MAX - 1)
enum {
TCP_METRICS_ATTR_UNSPEC,
TCP_METRICS_ATTR_ADDR_IPV4, /* u32 */
TCP_METRICS_ATTR_ADDR_IPV6, /* binary */
TCP_METRICS_ATTR_AGE, /* msecs */
TCP_METRICS_ATTR_TW_TSVAL, /* u32, raw, rcv tsval */
TCP_METRICS_ATTR_TW_TS_STAMP, /* s32, sec age */
TCP_METRICS_ATTR_VALS, /* nested +1, u32 */
TCP_METRICS_ATTR_FOPEN_MSS, /* u16 */
TCP_METRICS_ATTR_FOPEN_SYN_DROPS, /* u16, count of drops */
TCP_METRICS_ATTR_FOPEN_SYN_DROP_TS, /* msecs age */
TCP_METRICS_ATTR_FOPEN_COOKIE, /* binary */
TCP_METRICS_ATTR_SADDR_IPV4, /* u32 */
TCP_METRICS_ATTR_SADDR_IPV6, /* binary */
__TCP_METRICS_ATTR_MAX,
};
#define TCP_METRICS_ATTR_MAX (__TCP_METRICS_ATTR_MAX - 1)
enum {
TCP_METRICS_CMD_UNSPEC,
TCP_METRICS_CMD_GET,
TCP_METRICS_CMD_DEL,
__TCP_METRICS_CMD_MAX,
};
#define TCP_METRICS_CMD_MAX (__TCP_METRICS_CMD_MAX - 1)
#endif /* _LINUX_TCP_METRICS_H */