diff options
Diffstat (limited to 'net')
| -rw-r--r-- | net/ipv4/Kconfig | 10 | ||||
| -rw-r--r-- | net/ipv4/Makefile | 1 | ||||
| -rw-r--r-- | net/ipv4/tcp_compound.c | 448 |
3 files changed, 0 insertions, 459 deletions
diff --git a/net/ipv4/Kconfig b/net/ipv4/Kconfig index da33393be45..8514106761b 100644 --- a/net/ipv4/Kconfig +++ b/net/ipv4/Kconfig @@ -572,16 +572,6 @@ config TCP_CONG_VENO loss packets. See http://www.ntu.edu.sg/home5/ZHOU0022/papers/CPFu03a.pdf -config TCP_CONG_COMPOUND - tristate "TCP Compound" - depends on EXPERIMENTAL - default n - ---help--- - TCP Compound is a sender-side only change to TCP that uses - a mixed Reno/Vegas approach to calculate the cwnd. - For further details look here: - ftp://ftp.research.microsoft.com/pub/tr/TR-2005-86.pdf - endmenu config TCP_CONG_BIC diff --git a/net/ipv4/Makefile b/net/ipv4/Makefile index 38b8039bdd5..4878fc5be85 100644 --- a/net/ipv4/Makefile +++ b/net/ipv4/Makefile @@ -47,7 +47,6 @@ obj-$(CONFIG_TCP_CONG_VEGAS) += tcp_vegas.o obj-$(CONFIG_TCP_CONG_VENO) += tcp_veno.o obj-$(CONFIG_TCP_CONG_SCALABLE) += tcp_scalable.o obj-$(CONFIG_TCP_CONG_LP) += tcp_lp.o -obj-$(CONFIG_TCP_CONG_COMPOUND) += tcp_compound.o obj-$(CONFIG_XFRM) += xfrm4_policy.o xfrm4_state.o xfrm4_input.o \ xfrm4_output.o diff --git a/net/ipv4/tcp_compound.c b/net/ipv4/tcp_compound.c deleted file mode 100644 index bc54f7e9aea..00000000000 --- a/net/ipv4/tcp_compound.c +++ /dev/null @@ -1,448 +0,0 @@ -/* - * TCP Vegas congestion control - * - * This is based on the congestion detection/avoidance scheme described in - * Lawrence S. Brakmo and Larry L. Peterson. - * "TCP Vegas: End to end congestion avoidance on a global internet." - * IEEE Journal on Selected Areas in Communication, 13(8):1465--1480, - * October 1995. Available from: - * ftp://ftp.cs.arizona.edu/xkernel/Papers/jsac.ps - * - * See http://www.cs.arizona.edu/xkernel/ for their implementation. - * The main aspects that distinguish this implementation from the - * Arizona Vegas implementation are: - * o We do not change the loss detection or recovery mechanisms of - * Linux in any way. Linux already recovers from losses quite well, - * using fine-grained timers, NewReno, and FACK. - * o To avoid the performance penalty imposed by increasing cwnd - * only every-other RTT during slow start, we increase during - * every RTT during slow start, just like Reno. - * o Largely to allow continuous cwnd growth during slow start, - * we use the rate at which ACKs come back as the "actual" - * rate, rather than the rate at which data is sent. - * o To speed convergence to the right rate, we set the cwnd - * to achieve the right ("actual") rate when we exit slow start. - * o To filter out the noise caused by delayed ACKs, we use the - * minimum RTT sample observed during the last RTT to calculate - * the actual rate. - * o When the sender re-starts from idle, it waits until it has - * received ACKs for an entire flight of new data before making - * a cwnd adjustment decision. The original Vegas implementation - * assumed senders never went idle. - * - * - * TCP Compound based on TCP Vegas - * - * further details can be found here: - * ftp://ftp.research.microsoft.com/pub/tr/TR-2005-86.pdf - */ - -#include <linux/config.h> -#include <linux/mm.h> -#include <linux/module.h> -#include <linux/skbuff.h> -#include <linux/inet_diag.h> - -#include <net/tcp.h> - -/* Default values of the Vegas variables, in fixed-point representation - * with V_PARAM_SHIFT bits to the right of the binary point. - */ -#define V_PARAM_SHIFT 1 - -#define TCP_COMPOUND_ALPHA 3U -#define TCP_COMPOUND_BETA 1U -#define TCP_COMPOUND_GAMMA 30 -#define TCP_COMPOUND_ZETA 1 - -/* TCP compound variables */ -struct compound { - u32 beg_snd_nxt; /* right edge during last RTT */ - u32 beg_snd_una; /* left edge during last RTT */ - u32 beg_snd_cwnd; /* saves the size of the cwnd */ - u8 doing_vegas_now; /* if true, do vegas for this RTT */ - u16 cntRTT; /* # of RTTs measured within last RTT */ - u32 minRTT; /* min of RTTs measured within last RTT (in usec) */ - u32 baseRTT; /* the min of all Vegas RTT measurements seen (in usec) */ - - u32 cwnd; - u32 dwnd; -}; - -/* There are several situations when we must "re-start" Vegas: - * - * o when a connection is established - * o after an RTO - * o after fast recovery - * o when we send a packet and there is no outstanding - * unacknowledged data (restarting an idle connection) - * - * In these circumstances we cannot do a Vegas calculation at the - * end of the first RTT, because any calculation we do is using - * stale info -- both the saved cwnd and congestion feedback are - * stale. - * - * Instead we must wait until the completion of an RTT during - * which we actually receive ACKs. - */ -static inline void vegas_enable(struct sock *sk) -{ - const struct tcp_sock *tp = tcp_sk(sk); - struct compound *vegas = inet_csk_ca(sk); - - /* Begin taking Vegas samples next time we send something. */ - vegas->doing_vegas_now = 1; - - /* Set the beginning of the next send window. */ - vegas->beg_snd_nxt = tp->snd_nxt; - - vegas->cntRTT = 0; - vegas->minRTT = 0x7fffffff; -} - -/* Stop taking Vegas samples for now. */ -static inline void vegas_disable(struct sock *sk) -{ - struct compound *vegas = inet_csk_ca(sk); - - vegas->doing_vegas_now = 0; -} - -static void tcp_compound_init(struct sock *sk) -{ - struct compound *vegas = inet_csk_ca(sk); - const struct tcp_sock *tp = tcp_sk(sk); - - vegas->baseRTT = 0x7fffffff; - vegas_enable(sk); - - vegas->dwnd = 0; - vegas->cwnd = tp->snd_cwnd; -} - -/* Do RTT sampling needed for Vegas. - * Basically we: - * o min-filter RTT samples from within an RTT to get the current - * propagation delay + queuing delay (we are min-filtering to try to - * avoid the effects of delayed ACKs) - * o min-filter RTT samples from a much longer window (forever for now) - * to find the propagation delay (baseRTT) - */ -static void tcp_compound_rtt_calc(struct sock *sk, u32 usrtt) -{ - struct compound *vegas = inet_csk_ca(sk); - u32 vrtt = usrtt + 1; /* Never allow zero rtt or baseRTT */ - - /* Filter to find propagation delay: */ - if (vrtt < vegas->baseRTT) - vegas->baseRTT = vrtt; - - /* Find the min RTT during the last RTT to find - * the current prop. delay + queuing delay: - */ - - vegas->minRTT = min(vegas->minRTT, vrtt); - vegas->cntRTT++; -} - -static void tcp_compound_state(struct sock *sk, u8 ca_state) -{ - - if (ca_state == TCP_CA_Open) - vegas_enable(sk); - else - vegas_disable(sk); -} - - -/* 64bit divisor, dividend and result. dynamic precision */ -static inline u64 div64_64(u64 dividend, u64 divisor) -{ - u32 d = divisor; - - if (divisor > 0xffffffffULL) { - unsigned int shift = fls(divisor >> 32); - - d = divisor >> shift; - dividend >>= shift; - } - - /* avoid 64 bit division if possible */ - if (dividend >> 32) - do_div(dividend, d); - else - dividend = (u32) dividend / d; - - return dividend; -} - -/* calculate the quartic root of "a" using Newton-Raphson */ -static u32 qroot(u64 a) -{ - u32 x, x1; - - /* Initial estimate is based on: - * qrt(x) = exp(log(x) / 4) - */ - x = 1u << (fls64(a) >> 2); - - /* - * Iteration based on: - * 3 - * x = ( 3 * x + a / x ) / 4 - * k+1 k k - */ - do { - u64 x3 = x; - - x1 = x; - x3 *= x; - x3 *= x; - - x = (3 * x + (u32) div64_64(a, x3)) / 4; - } while (abs(x1 - x) > 1); - - return x; -} - - -/* - * If the connection is idle and we are restarting, - * then we don't want to do any Vegas calculations - * until we get fresh RTT samples. So when we - * restart, we reset our Vegas state to a clean - * slate. After we get acks for this flight of - * packets, _then_ we can make Vegas calculations - * again. - */ -static void tcp_compound_cwnd_event(struct sock *sk, enum tcp_ca_event event) -{ - if (event == CA_EVENT_CWND_RESTART || event == CA_EVENT_TX_START) - tcp_compound_init(sk); -} - -static void tcp_compound_cong_avoid(struct sock *sk, u32 ack, - u32 seq_rtt, u32 in_flight, int flag) -{ - struct tcp_sock *tp = tcp_sk(sk); - struct compound *vegas = inet_csk_ca(sk); - u8 inc = 0; - - if (vegas->cwnd + vegas->dwnd > tp->snd_cwnd) { - if (vegas->cwnd > tp->snd_cwnd || vegas->dwnd > tp->snd_cwnd) { - vegas->cwnd = tp->snd_cwnd; - vegas->dwnd = 0; - } else - vegas->cwnd = tp->snd_cwnd - vegas->dwnd; - - } - - if (!tcp_is_cwnd_limited(sk, in_flight)) - return; - - if (vegas->cwnd <= tp->snd_ssthresh) - inc = 1; - else if (tp->snd_cwnd_cnt < tp->snd_cwnd) - tp->snd_cwnd_cnt++; - - if (tp->snd_cwnd_cnt >= tp->snd_cwnd) { - inc = 1; - tp->snd_cwnd_cnt = 0; - } - - if (inc && tp->snd_cwnd < tp->snd_cwnd_clamp) - vegas->cwnd++; - - /* The key players are v_beg_snd_una and v_beg_snd_nxt. - * - * These are so named because they represent the approximate values - * of snd_una and snd_nxt at the beginning of the current RTT. More - * precisely, they represent the amount of data sent during the RTT. - * At the end of the RTT, when we receive an ACK for v_beg_snd_nxt, - * we will calculate that (v_beg_snd_nxt - v_beg_snd_una) outstanding - * bytes of data have been ACKed during the course of the RTT, giving - * an "actual" rate of: - * - * (v_beg_snd_nxt - v_beg_snd_una) / (rtt duration) - * - * Unfortunately, v_beg_snd_una is not exactly equal to snd_una, - * because delayed ACKs can cover more than one segment, so they - * don't line up nicely with the boundaries of RTTs. - * - * Another unfortunate fact of life is that delayed ACKs delay the - * advance of the left edge of our send window, so that the number - * of bytes we send in an RTT is often less than our cwnd will allow. - * So we keep track of our cwnd separately, in v_beg_snd_cwnd. - */ - - if (after(ack, vegas->beg_snd_nxt)) { - /* Do the Vegas once-per-RTT cwnd adjustment. */ - u32 old_wnd, old_snd_cwnd; - - /* Here old_wnd is essentially the window of data that was - * sent during the previous RTT, and has all - * been acknowledged in the course of the RTT that ended - * with the ACK we just received. Likewise, old_snd_cwnd - * is the cwnd during the previous RTT. - */ - if (!tp->mss_cache) - return; - - old_wnd = (vegas->beg_snd_nxt - vegas->beg_snd_una) / - tp->mss_cache; - old_snd_cwnd = vegas->beg_snd_cwnd; - - /* Save the extent of the current window so we can use this - * at the end of the next RTT. - */ - vegas->beg_snd_una = vegas->beg_snd_nxt; - vegas->beg_snd_nxt = tp->snd_nxt; - vegas->beg_snd_cwnd = tp->snd_cwnd; - - /* We do the Vegas calculations only if we got enough RTT - * samples that we can be reasonably sure that we got - * at least one RTT sample that wasn't from a delayed ACK. - * If we only had 2 samples total, - * then that means we're getting only 1 ACK per RTT, which - * means they're almost certainly delayed ACKs. - * If we have 3 samples, we should be OK. - */ - - if (vegas->cntRTT > 2) { - u32 rtt, target_cwnd, diff; - u32 brtt, dwnd; - - /* We have enough RTT samples, so, using the Vegas - * algorithm, we determine if we should increase or - * decrease cwnd, and by how much. - */ - - /* Pluck out the RTT we are using for the Vegas - * calculations. This is the min RTT seen during the - * last RTT. Taking the min filters out the effects - * of delayed ACKs, at the cost of noticing congestion - * a bit later. - */ - rtt = vegas->minRTT; - - /* Calculate the cwnd we should have, if we weren't - * going too fast. - * - * This is: - * (actual rate in segments) * baseRTT - * We keep it as a fixed point number with - * V_PARAM_SHIFT bits to the right of the binary point. - */ - if (!rtt) - return; - - brtt = vegas->baseRTT; - target_cwnd = ((old_wnd * brtt) - << V_PARAM_SHIFT) / rtt; - - /* Calculate the difference between the window we had, - * and the window we would like to have. This quantity - * is the "Diff" from the Arizona Vegas papers. - * - * Again, this is a fixed point number with - * V_PARAM_SHIFT bits to the right of the binary - * point. - */ - - diff = (old_wnd << V_PARAM_SHIFT) - target_cwnd; - - dwnd = vegas->dwnd; - - if (diff < (TCP_COMPOUND_GAMMA << V_PARAM_SHIFT)) { - u64 v; - u32 x; - - /* - * The TCP Compound paper describes the choice - * of "k" determines the agressiveness, - * ie. slope of the response function. - * - * For same value as HSTCP would be 0.8 - * but for computaional reasons, both the - * original authors and this implementation - * use 0.75. - */ - v = old_wnd; - x = qroot(v * v * v) >> TCP_COMPOUND_ALPHA; - if (x > 1) - dwnd = x - 1; - else - dwnd = 0; - - dwnd += vegas->dwnd; - - } else if ((dwnd << V_PARAM_SHIFT) < - (diff * TCP_COMPOUND_BETA)) - dwnd = 0; - else - dwnd = - ((dwnd << V_PARAM_SHIFT) - - (diff * - TCP_COMPOUND_BETA)) >> V_PARAM_SHIFT; - - vegas->dwnd = dwnd; - - } - - /* Wipe the slate clean for the next RTT. */ - vegas->cntRTT = 0; - vegas->minRTT = 0x7fffffff; - } - - tp->snd_cwnd = vegas->cwnd + vegas->dwnd; -} - -/* Extract info for Tcp socket info provided via netlink. */ -static void tcp_compound_get_info(struct sock *sk, u32 ext, struct sk_buff *skb) -{ - const struct compound *ca = inet_csk_ca(sk); - if (ext & (1 << (INET_DIAG_VEGASINFO - 1))) { - struct tcpvegas_info *info; - - info = RTA_DATA(__RTA_PUT(skb, INET_DIAG_VEGASINFO, - sizeof(*info))); - - info->tcpv_enabled = ca->doing_vegas_now; - info->tcpv_rttcnt = ca->cntRTT; - info->tcpv_rtt = ca->baseRTT; - info->tcpv_minrtt = ca->minRTT; - rtattr_failure:; - } -} - -static struct tcp_congestion_ops tcp_compound = { - .init = tcp_compound_init, - .ssthresh = tcp_reno_ssthresh, - .cong_avoid = tcp_compound_cong_avoid, - .rtt_sample = tcp_compound_rtt_calc, - .set_state = tcp_compound_state, - .cwnd_event = tcp_compound_cwnd_event, - .get_info = tcp_compound_get_info, - - .owner = THIS_MODULE, - .name = "compound", -}; - -static int __init tcp_compound_register(void) -{ - BUG_ON(sizeof(struct compound) > ICSK_CA_PRIV_SIZE); - tcp_register_congestion_control(&tcp_compound); - return 0; -} - -static void __exit tcp_compound_unregister(void) -{ - tcp_unregister_congestion_control(&tcp_compound); -} - -module_init(tcp_compound_register); -module_exit(tcp_compound_unregister); - -MODULE_AUTHOR("Angelo P. Castellani, Stephen Hemminger"); -MODULE_LICENSE("GPL"); -MODULE_DESCRIPTION("TCP Compound"); |