![Arnaldo Carvalho de Melo](/assets/img/avatar_default.png)
This changeset basically moves tcp_sk()->{ca_ops,ca_state,etc} to inet_csk(), minimal renaming/moving done in this changeset to ease review. Most of it is just changes of struct tcp_sock * to struct sock * parameters. With this we move to a state closer to two interesting goals: 1. Generalisation of net/ipv4/tcp_diag.c, becoming inet_diag.c, being used for any INET transport protocol that has struct inet_hashinfo and are derived from struct inet_connection_sock. Keeps the userspace API, that will just not display DCCP sockets, while newer versions of tools can support DCCP. 2. INET generic transport pluggable Congestion Avoidance infrastructure, using the current TCP CA infrastructure with DCCP. Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com> Signed-off-by: David S. Miller <davem@davemloft.net>
264 lines
6.7 KiB
C
264 lines
6.7 KiB
C
/*
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* TCP Westwood+
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*
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* Angelo Dell'Aera: TCP Westwood+ support
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*/
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#include <linux/config.h>
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#include <linux/mm.h>
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#include <linux/module.h>
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#include <linux/skbuff.h>
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#include <linux/tcp_diag.h>
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#include <net/tcp.h>
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/* TCP Westwood structure */
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struct westwood {
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u32 bw_ns_est; /* first bandwidth estimation..not too smoothed 8) */
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u32 bw_est; /* bandwidth estimate */
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u32 rtt_win_sx; /* here starts a new evaluation... */
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u32 bk;
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u32 snd_una; /* used for evaluating the number of acked bytes */
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u32 cumul_ack;
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u32 accounted;
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u32 rtt;
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u32 rtt_min; /* minimum observed RTT */
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};
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/* TCP Westwood functions and constants */
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#define TCP_WESTWOOD_RTT_MIN (HZ/20) /* 50ms */
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#define TCP_WESTWOOD_INIT_RTT (20*HZ) /* maybe too conservative?! */
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/*
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* @tcp_westwood_create
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* This function initializes fields used in TCP Westwood+,
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* it is called after the initial SYN, so the sequence numbers
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* are correct but new passive connections we have no
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* information about RTTmin at this time so we simply set it to
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* TCP_WESTWOOD_INIT_RTT. This value was chosen to be too conservative
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* since in this way we're sure it will be updated in a consistent
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* way as soon as possible. It will reasonably happen within the first
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* RTT period of the connection lifetime.
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*/
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static void tcp_westwood_init(struct sock *sk)
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{
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struct westwood *w = inet_csk_ca(sk);
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w->bk = 0;
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w->bw_ns_est = 0;
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w->bw_est = 0;
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w->accounted = 0;
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w->cumul_ack = 0;
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w->rtt_min = w->rtt = TCP_WESTWOOD_INIT_RTT;
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w->rtt_win_sx = tcp_time_stamp;
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w->snd_una = tcp_sk(sk)->snd_una;
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}
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/*
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* @westwood_do_filter
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* Low-pass filter. Implemented using constant coefficients.
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*/
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static inline u32 westwood_do_filter(u32 a, u32 b)
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{
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return (((7 * a) + b) >> 3);
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}
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static inline void westwood_filter(struct westwood *w, u32 delta)
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{
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w->bw_ns_est = westwood_do_filter(w->bw_ns_est, w->bk / delta);
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w->bw_est = westwood_do_filter(w->bw_est, w->bw_ns_est);
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}
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/*
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* @westwood_pkts_acked
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* Called after processing group of packets.
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* but all westwood needs is the last sample of srtt.
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*/
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static void tcp_westwood_pkts_acked(struct sock *sk, u32 cnt)
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{
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struct westwood *w = inet_csk_ca(sk);
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if (cnt > 0)
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w->rtt = tcp_sk(sk)->srtt >> 3;
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}
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/*
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* @westwood_update_window
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* It updates RTT evaluation window if it is the right moment to do
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* it. If so it calls filter for evaluating bandwidth.
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*/
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static void westwood_update_window(struct sock *sk)
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{
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struct westwood *w = inet_csk_ca(sk);
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s32 delta = tcp_time_stamp - w->rtt_win_sx;
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/*
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* See if a RTT-window has passed.
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* Be careful since if RTT is less than
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* 50ms we don't filter but we continue 'building the sample'.
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* This minimum limit was chosen since an estimation on small
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* time intervals is better to avoid...
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* Obviously on a LAN we reasonably will always have
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* right_bound = left_bound + WESTWOOD_RTT_MIN
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*/
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if (w->rtt && delta > max_t(u32, w->rtt, TCP_WESTWOOD_RTT_MIN)) {
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westwood_filter(w, delta);
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w->bk = 0;
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w->rtt_win_sx = tcp_time_stamp;
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}
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}
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/*
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* @westwood_fast_bw
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* It is called when we are in fast path. In particular it is called when
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* header prediction is successful. In such case in fact update is
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* straight forward and doesn't need any particular care.
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*/
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static inline void westwood_fast_bw(struct sock *sk)
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{
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const struct tcp_sock *tp = tcp_sk(sk);
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struct westwood *w = inet_csk_ca(sk);
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westwood_update_window(sk);
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w->bk += tp->snd_una - w->snd_una;
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w->snd_una = tp->snd_una;
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w->rtt_min = min(w->rtt, w->rtt_min);
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}
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/*
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* @westwood_acked_count
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* This function evaluates cumul_ack for evaluating bk in case of
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* delayed or partial acks.
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*/
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static inline u32 westwood_acked_count(struct sock *sk)
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{
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const struct tcp_sock *tp = tcp_sk(sk);
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struct westwood *w = inet_csk_ca(sk);
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w->cumul_ack = tp->snd_una - w->snd_una;
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/* If cumul_ack is 0 this is a dupack since it's not moving
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* tp->snd_una.
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*/
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if (!w->cumul_ack) {
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w->accounted += tp->mss_cache;
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w->cumul_ack = tp->mss_cache;
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}
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if (w->cumul_ack > tp->mss_cache) {
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/* Partial or delayed ack */
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if (w->accounted >= w->cumul_ack) {
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w->accounted -= w->cumul_ack;
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w->cumul_ack = tp->mss_cache;
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} else {
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w->cumul_ack -= w->accounted;
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w->accounted = 0;
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}
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}
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w->snd_una = tp->snd_una;
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return w->cumul_ack;
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}
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static inline u32 westwood_bw_rttmin(const struct sock *sk)
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{
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const struct tcp_sock *tp = tcp_sk(sk);
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const struct westwood *w = inet_csk_ca(sk);
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return max_t(u32, (w->bw_est * w->rtt_min) / tp->mss_cache, 2);
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}
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/*
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* TCP Westwood
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* Here limit is evaluated as Bw estimation*RTTmin (for obtaining it
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* in packets we use mss_cache). Rttmin is guaranteed to be >= 2
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* so avoids ever returning 0.
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*/
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static u32 tcp_westwood_cwnd_min(struct sock *sk)
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{
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return westwood_bw_rttmin(sk);
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}
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static void tcp_westwood_event(struct sock *sk, enum tcp_ca_event event)
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{
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struct tcp_sock *tp = tcp_sk(sk);
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struct westwood *w = inet_csk_ca(sk);
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switch(event) {
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case CA_EVENT_FAST_ACK:
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westwood_fast_bw(sk);
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break;
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case CA_EVENT_COMPLETE_CWR:
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tp->snd_cwnd = tp->snd_ssthresh = westwood_bw_rttmin(sk);
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break;
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case CA_EVENT_FRTO:
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tp->snd_ssthresh = westwood_bw_rttmin(sk);
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break;
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case CA_EVENT_SLOW_ACK:
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westwood_update_window(sk);
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w->bk += westwood_acked_count(sk);
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w->rtt_min = min(w->rtt, w->rtt_min);
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break;
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default:
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/* don't care */
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break;
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}
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}
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/* Extract info for Tcp socket info provided via netlink. */
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static void tcp_westwood_info(struct sock *sk, u32 ext,
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struct sk_buff *skb)
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{
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const struct westwood *ca = inet_csk_ca(sk);
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if (ext & (1<<(TCPDIAG_VEGASINFO-1))) {
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struct rtattr *rta;
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struct tcpvegas_info *info;
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rta = __RTA_PUT(skb, TCPDIAG_VEGASINFO, sizeof(*info));
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info = RTA_DATA(rta);
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info->tcpv_enabled = 1;
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info->tcpv_rttcnt = 0;
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info->tcpv_rtt = jiffies_to_usecs(ca->rtt);
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info->tcpv_minrtt = jiffies_to_usecs(ca->rtt_min);
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rtattr_failure: ;
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}
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}
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static struct tcp_congestion_ops tcp_westwood = {
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.init = tcp_westwood_init,
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.ssthresh = tcp_reno_ssthresh,
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.cong_avoid = tcp_reno_cong_avoid,
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.min_cwnd = tcp_westwood_cwnd_min,
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.cwnd_event = tcp_westwood_event,
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.get_info = tcp_westwood_info,
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.pkts_acked = tcp_westwood_pkts_acked,
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.owner = THIS_MODULE,
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.name = "westwood"
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};
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static int __init tcp_westwood_register(void)
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{
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BUG_ON(sizeof(struct westwood) > ICSK_CA_PRIV_SIZE);
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return tcp_register_congestion_control(&tcp_westwood);
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}
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static void __exit tcp_westwood_unregister(void)
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{
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tcp_unregister_congestion_control(&tcp_westwood);
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}
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module_init(tcp_westwood_register);
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module_exit(tcp_westwood_unregister);
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MODULE_AUTHOR("Stephen Hemminger, Angelo Dell'Aera");
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MODULE_LICENSE("GPL");
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MODULE_DESCRIPTION("TCP Westwood+");
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