136 lines
3.7 KiB
C
136 lines
3.7 KiB
C
#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/inet_diag.h>
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#include <asm/div64.h>
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#include <net/tcp.h>
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/* Vegas variables */
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struct vegas {
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u32 beg_snd_nxt; /* right edge during last RTT */
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u32 beg_snd_una; /* left edge during last RTT */
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u32 beg_snd_cwnd; /* saves the size of the cwnd */
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u8 doing_vegas_now;/* if true, do vegas for this RTT */
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u16 cntRTT; /* # of RTTs measured within last RTT */
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u32 minRTT; /* min of RTTs measured within last RTT (in usec) */
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u32 baseRTT; /* the min of all Vegas RTT measurements seen (in usec) */
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};
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/* There are several situations when we must "re-start" Vegas:
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*
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* o when a connection is established
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* o after an RTO
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* o after fast recovery
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* o when we send a packet and there is no outstanding
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* unacknowledged data (restarting an idle connection)
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*
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* In these circumstances we cannot do a Vegas calculation at the
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* end of the first RTT, because any calculation we do is using
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* stale info -- both the saved cwnd and congestion feedback are
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* stale.
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*
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* Instead we must wait until the completion of an RTT during
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* which we actually receive ACKs.
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*/
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static inline void vegas_enable(struct sock *sk)
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{
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const struct tcp_sock *tp = tcp_sk(sk);
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struct vegas *vegas = inet_csk_ca(sk);
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/* Begin taking Vegas samples next time we send something. */
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vegas->doing_vegas_now = 1;
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/* Set the beginning of the next send window. */
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vegas->beg_snd_nxt = tp->snd_nxt;
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vegas->cntRTT = 0;
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vegas->minRTT = 0x7fffffff;
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}
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/* Stop taking Vegas samples for now. */
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static inline void vegas_disable(struct sock *sk)
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{
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struct vegas *vegas = inet_csk_ca(sk);
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vegas->doing_vegas_now = 0;
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}
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static void tcp_vegas_init(struct sock *sk)
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{
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struct vegas *vegas = inet_csk_ca(sk);
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vegas->baseRTT = 0x7fffffff;
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vegas_enable(sk);
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}
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static void tcp_vegas_state(struct sock *sk, u8 ca_state)
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{
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if (ca_state == TCP_CA_Open)
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vegas_enable(sk);
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else
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vegas_disable(sk);
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}
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/* Do RTT sampling needed for Vegas.
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* Basically we:
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* o min-filter RTT samples from within an RTT to get the current
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* propagation delay + queuing delay (we are min-filtering to try to
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* avoid the effects of delayed ACKs)
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* o min-filter RTT samples from a much longer window (forever for now)
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* to find the propagation delay (baseRTT)
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*/
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static void tcp_vegas_rtt_calc(struct sock *sk, u32 usrtt)
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{
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struct vegas *vegas = inet_csk_ca(sk);
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u32 vrtt = usrtt + 1; /* Never allow zero rtt or baseRTT */
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/* Filter to find propagation delay: */
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if (vrtt < vegas->baseRTT)
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vegas->baseRTT = vrtt;
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/* Find the min RTT during the last RTT to find
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* the current prop. delay + queuing delay:
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*/
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vegas->minRTT = min(vegas->minRTT, vrtt);
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vegas->cntRTT++;
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}
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/*
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* If the connection is idle and we are restarting,
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* then we don't want to do any Vegas calculations
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* until we get fresh RTT samples. So when we
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* restart, we reset our Vegas state to a clean
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* slate. After we get acks for this flight of
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* packets, _then_ we can make Vegas calculations
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* again.
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*/
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static void tcp_vegas_cwnd_event(struct sock *sk, enum tcp_ca_event event)
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{
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if (event == CA_EVENT_CWND_RESTART ||
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event == CA_EVENT_TX_START)
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tcp_vegas_init(sk);
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}
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/* Extract info for Tcp socket info provided via netlink. */
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static void tcp_vegas_get_info(struct sock *sk, u32 ext,
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struct sk_buff *skb)
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{
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const struct vegas *ca = inet_csk_ca(sk);
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if (ext & (1 << (INET_DIAG_VEGASINFO - 1))) {
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struct tcpvegas_info *info;
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info = RTA_DATA(__RTA_PUT(skb, INET_DIAG_VEGASINFO,
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sizeof(*info)));
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info->tcpv_enabled = ca->doing_vegas_now;
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info->tcpv_rttcnt = ca->cntRTT;
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info->tcpv_rtt = ca->baseRTT;
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info->tcpv_minrtt = ca->minRTT;
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rtattr_failure: ;
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}
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}
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