diff --git a/fs/afs/fs_probe.c b/fs/afs/fs_probe.c index e1b9ed679045..02e976ca5732 100644 --- a/fs/afs/fs_probe.c +++ b/fs/afs/fs_probe.c @@ -32,9 +32,8 @@ void afs_fileserver_probe_result(struct afs_call *call) struct afs_server *server = call->server; unsigned int server_index = call->server_index; unsigned int index = call->addr_ix; - unsigned int rtt = UINT_MAX; + unsigned int rtt_us; bool have_result = false; - u64 _rtt; int ret = call->error; _enter("%pU,%u", &server->uuid, index); @@ -93,15 +92,9 @@ responded: } } - /* Get the RTT and scale it to fit into a 32-bit value that represents - * over a minute of time so that we can access it with one instruction - * on a 32-bit system. - */ - _rtt = rxrpc_kernel_get_rtt(call->net->socket, call->rxcall); - _rtt /= 64; - rtt = (_rtt > UINT_MAX) ? UINT_MAX : _rtt; - if (rtt < server->probe.rtt) { - server->probe.rtt = rtt; + rtt_us = rxrpc_kernel_get_srtt(call->net->socket, call->rxcall); + if (rtt_us < server->probe.rtt) { + server->probe.rtt = rtt_us; alist->preferred = index; have_result = true; } @@ -113,8 +106,7 @@ out: spin_unlock(&server->probe_lock); _debug("probe [%u][%u] %pISpc rtt=%u ret=%d", - server_index, index, &alist->addrs[index].transport, - (unsigned int)rtt, ret); + server_index, index, &alist->addrs[index].transport, rtt_us, ret); have_result |= afs_fs_probe_done(server); if (have_result) { diff --git a/fs/afs/vl_probe.c b/fs/afs/vl_probe.c index 858498cc1b05..e3aa013c2177 100644 --- a/fs/afs/vl_probe.c +++ b/fs/afs/vl_probe.c @@ -31,10 +31,9 @@ void afs_vlserver_probe_result(struct afs_call *call) struct afs_addr_list *alist = call->alist; struct afs_vlserver *server = call->vlserver; unsigned int server_index = call->server_index; + unsigned int rtt_us = 0; unsigned int index = call->addr_ix; - unsigned int rtt = UINT_MAX; bool have_result = false; - u64 _rtt; int ret = call->error; _enter("%s,%u,%u,%d,%d", server->name, server_index, index, ret, call->abort_code); @@ -93,15 +92,9 @@ responded: } } - /* Get the RTT and scale it to fit into a 32-bit value that represents - * over a minute of time so that we can access it with one instruction - * on a 32-bit system. - */ - _rtt = rxrpc_kernel_get_rtt(call->net->socket, call->rxcall); - _rtt /= 64; - rtt = (_rtt > UINT_MAX) ? UINT_MAX : _rtt; - if (rtt < server->probe.rtt) { - server->probe.rtt = rtt; + rtt_us = rxrpc_kernel_get_srtt(call->net->socket, call->rxcall); + if (rtt_us < server->probe.rtt) { + server->probe.rtt = rtt_us; alist->preferred = index; have_result = true; } @@ -113,8 +106,7 @@ out: spin_unlock(&server->probe_lock); _debug("probe [%u][%u] %pISpc rtt=%u ret=%d", - server_index, index, &alist->addrs[index].transport, - (unsigned int)rtt, ret); + server_index, index, &alist->addrs[index].transport, rtt_us, ret); have_result |= afs_vl_probe_done(server); if (have_result) { diff --git a/include/net/af_rxrpc.h b/include/net/af_rxrpc.h index 04e97bab6f28..ab988940bf04 100644 --- a/include/net/af_rxrpc.h +++ b/include/net/af_rxrpc.h @@ -59,7 +59,7 @@ bool rxrpc_kernel_abort_call(struct socket *, struct rxrpc_call *, void rxrpc_kernel_end_call(struct socket *, struct rxrpc_call *); void rxrpc_kernel_get_peer(struct socket *, struct rxrpc_call *, struct sockaddr_rxrpc *); -u64 rxrpc_kernel_get_rtt(struct socket *, struct rxrpc_call *); +u32 rxrpc_kernel_get_srtt(struct socket *, struct rxrpc_call *); int rxrpc_kernel_charge_accept(struct socket *, rxrpc_notify_rx_t, rxrpc_user_attach_call_t, unsigned long, gfp_t, unsigned int); diff --git a/include/trace/events/rxrpc.h b/include/trace/events/rxrpc.h index 191fe447f990..ab75f261f04a 100644 --- a/include/trace/events/rxrpc.h +++ b/include/trace/events/rxrpc.h @@ -1112,18 +1112,17 @@ TRACE_EVENT(rxrpc_rtt_tx, TRACE_EVENT(rxrpc_rtt_rx, TP_PROTO(struct rxrpc_call *call, enum rxrpc_rtt_rx_trace why, rxrpc_serial_t send_serial, rxrpc_serial_t resp_serial, - s64 rtt, u8 nr, s64 avg), + u32 rtt, u32 rto), - TP_ARGS(call, why, send_serial, resp_serial, rtt, nr, avg), + TP_ARGS(call, why, send_serial, resp_serial, rtt, rto), TP_STRUCT__entry( __field(unsigned int, call ) __field(enum rxrpc_rtt_rx_trace, why ) - __field(u8, nr ) __field(rxrpc_serial_t, send_serial ) __field(rxrpc_serial_t, resp_serial ) - __field(s64, rtt ) - __field(u64, avg ) + __field(u32, rtt ) + __field(u32, rto ) ), TP_fast_assign( @@ -1132,18 +1131,16 @@ TRACE_EVENT(rxrpc_rtt_rx, __entry->send_serial = send_serial; __entry->resp_serial = resp_serial; __entry->rtt = rtt; - __entry->nr = nr; - __entry->avg = avg; + __entry->rto = rto; ), - TP_printk("c=%08x %s sr=%08x rr=%08x rtt=%lld nr=%u avg=%lld", + TP_printk("c=%08x %s sr=%08x rr=%08x rtt=%u rto=%u", __entry->call, __print_symbolic(__entry->why, rxrpc_rtt_rx_traces), __entry->send_serial, __entry->resp_serial, __entry->rtt, - __entry->nr, - __entry->avg) + __entry->rto) ); TRACE_EVENT(rxrpc_timer, diff --git a/net/rxrpc/Makefile b/net/rxrpc/Makefile index 6ffb7e9887ce..ddd0f95713a9 100644 --- a/net/rxrpc/Makefile +++ b/net/rxrpc/Makefile @@ -25,6 +25,7 @@ rxrpc-y := \ peer_event.o \ peer_object.o \ recvmsg.o \ + rtt.o \ security.o \ sendmsg.o \ skbuff.o \ diff --git a/net/rxrpc/ar-internal.h b/net/rxrpc/ar-internal.h index 3eb1ab40ca5c..9fe264bec70c 100644 --- a/net/rxrpc/ar-internal.h +++ b/net/rxrpc/ar-internal.h @@ -7,6 +7,7 @@ #include #include +#include #include #include #include @@ -311,11 +312,14 @@ struct rxrpc_peer { #define RXRPC_RTT_CACHE_SIZE 32 spinlock_t rtt_input_lock; /* RTT lock for input routine */ ktime_t rtt_last_req; /* Time of last RTT request */ - u64 rtt; /* Current RTT estimate (in nS) */ - u64 rtt_sum; /* Sum of cache contents */ - u64 rtt_cache[RXRPC_RTT_CACHE_SIZE]; /* Determined RTT cache */ - u8 rtt_cursor; /* next entry at which to insert */ - u8 rtt_usage; /* amount of cache actually used */ + unsigned int rtt_count; /* Number of samples we've got */ + + u32 srtt_us; /* smoothed round trip time << 3 in usecs */ + u32 mdev_us; /* medium deviation */ + u32 mdev_max_us; /* maximal mdev for the last rtt period */ + u32 rttvar_us; /* smoothed mdev_max */ + u32 rto_j; /* Retransmission timeout in jiffies */ + u8 backoff; /* Backoff timeout */ u8 cong_cwnd; /* Congestion window size */ }; @@ -1041,7 +1045,6 @@ extern unsigned long rxrpc_idle_ack_delay; extern unsigned int rxrpc_rx_window_size; extern unsigned int rxrpc_rx_mtu; extern unsigned int rxrpc_rx_jumbo_max; -extern unsigned long rxrpc_resend_timeout; extern const s8 rxrpc_ack_priority[]; @@ -1069,8 +1072,6 @@ void rxrpc_send_keepalive(struct rxrpc_peer *); * peer_event.c */ void rxrpc_error_report(struct sock *); -void rxrpc_peer_add_rtt(struct rxrpc_call *, enum rxrpc_rtt_rx_trace, - rxrpc_serial_t, rxrpc_serial_t, ktime_t, ktime_t); void rxrpc_peer_keepalive_worker(struct work_struct *); /* @@ -1102,6 +1103,14 @@ extern const struct seq_operations rxrpc_peer_seq_ops; void rxrpc_notify_socket(struct rxrpc_call *); int rxrpc_recvmsg(struct socket *, struct msghdr *, size_t, int); +/* + * rtt.c + */ +void rxrpc_peer_add_rtt(struct rxrpc_call *, enum rxrpc_rtt_rx_trace, + rxrpc_serial_t, rxrpc_serial_t, ktime_t, ktime_t); +unsigned long rxrpc_get_rto_backoff(struct rxrpc_peer *, bool); +void rxrpc_peer_init_rtt(struct rxrpc_peer *); + /* * rxkad.c */ diff --git a/net/rxrpc/call_accept.c b/net/rxrpc/call_accept.c index 70e44abf106c..b7611cc159e5 100644 --- a/net/rxrpc/call_accept.c +++ b/net/rxrpc/call_accept.c @@ -248,7 +248,7 @@ static void rxrpc_send_ping(struct rxrpc_call *call, struct sk_buff *skb) struct rxrpc_skb_priv *sp = rxrpc_skb(skb); ktime_t now = skb->tstamp; - if (call->peer->rtt_usage < 3 || + if (call->peer->rtt_count < 3 || ktime_before(ktime_add_ms(call->peer->rtt_last_req, 1000), now)) rxrpc_propose_ACK(call, RXRPC_ACK_PING, sp->hdr.serial, true, true, diff --git a/net/rxrpc/call_event.c b/net/rxrpc/call_event.c index cedbbb3a7c2e..2a65ac41055f 100644 --- a/net/rxrpc/call_event.c +++ b/net/rxrpc/call_event.c @@ -111,8 +111,8 @@ static void __rxrpc_propose_ACK(struct rxrpc_call *call, u8 ack_reason, } else { unsigned long now = jiffies, ack_at; - if (call->peer->rtt_usage > 0) - ack_at = nsecs_to_jiffies(call->peer->rtt); + if (call->peer->srtt_us != 0) + ack_at = usecs_to_jiffies(call->peer->srtt_us >> 3); else ack_at = expiry; @@ -157,24 +157,18 @@ static void rxrpc_congestion_timeout(struct rxrpc_call *call) static void rxrpc_resend(struct rxrpc_call *call, unsigned long now_j) { struct sk_buff *skb; - unsigned long resend_at; + unsigned long resend_at, rto_j; rxrpc_seq_t cursor, seq, top; - ktime_t now, max_age, oldest, ack_ts, timeout, min_timeo; + ktime_t now, max_age, oldest, ack_ts; int ix; u8 annotation, anno_type, retrans = 0, unacked = 0; _enter("{%d,%d}", call->tx_hard_ack, call->tx_top); - if (call->peer->rtt_usage > 1) - timeout = ns_to_ktime(call->peer->rtt * 3 / 2); - else - timeout = ms_to_ktime(rxrpc_resend_timeout); - min_timeo = ns_to_ktime((1000000000 / HZ) * 4); - if (ktime_before(timeout, min_timeo)) - timeout = min_timeo; + rto_j = call->peer->rto_j; now = ktime_get_real(); - max_age = ktime_sub(now, timeout); + max_age = ktime_sub(now, jiffies_to_usecs(rto_j)); spin_lock_bh(&call->lock); @@ -219,7 +213,7 @@ static void rxrpc_resend(struct rxrpc_call *call, unsigned long now_j) } resend_at = nsecs_to_jiffies(ktime_to_ns(ktime_sub(now, oldest))); - resend_at += jiffies + rxrpc_resend_timeout; + resend_at += jiffies + rto_j; WRITE_ONCE(call->resend_at, resend_at); if (unacked) @@ -234,7 +228,7 @@ static void rxrpc_resend(struct rxrpc_call *call, unsigned long now_j) rxrpc_timer_set_for_resend); spin_unlock_bh(&call->lock); ack_ts = ktime_sub(now, call->acks_latest_ts); - if (ktime_to_ns(ack_ts) < call->peer->rtt) + if (ktime_to_us(ack_ts) < (call->peer->srtt_us >> 3)) goto out; rxrpc_propose_ACK(call, RXRPC_ACK_PING, 0, true, false, rxrpc_propose_ack_ping_for_lost_ack); diff --git a/net/rxrpc/input.c b/net/rxrpc/input.c index 69e09d69c896..e438bfd3fdf5 100644 --- a/net/rxrpc/input.c +++ b/net/rxrpc/input.c @@ -91,11 +91,11 @@ static void rxrpc_congestion_management(struct rxrpc_call *call, /* We analyse the number of packets that get ACK'd per RTT * period and increase the window if we managed to fill it. */ - if (call->peer->rtt_usage == 0) + if (call->peer->rtt_count == 0) goto out; if (ktime_before(skb->tstamp, - ktime_add_ns(call->cong_tstamp, - call->peer->rtt))) + ktime_add_us(call->cong_tstamp, + call->peer->srtt_us >> 3))) goto out_no_clear_ca; change = rxrpc_cong_rtt_window_end; call->cong_tstamp = skb->tstamp; diff --git a/net/rxrpc/misc.c b/net/rxrpc/misc.c index 214405f75346..d4144fd86f84 100644 --- a/net/rxrpc/misc.c +++ b/net/rxrpc/misc.c @@ -63,11 +63,6 @@ unsigned int rxrpc_rx_mtu = 5692; */ unsigned int rxrpc_rx_jumbo_max = 4; -/* - * Time till packet resend (in milliseconds). - */ -unsigned long rxrpc_resend_timeout = 4 * HZ; - const s8 rxrpc_ack_priority[] = { [0] = 0, [RXRPC_ACK_DELAY] = 1, diff --git a/net/rxrpc/output.c b/net/rxrpc/output.c index 90e263c6aa69..f8b632a5c619 100644 --- a/net/rxrpc/output.c +++ b/net/rxrpc/output.c @@ -369,7 +369,7 @@ int rxrpc_send_data_packet(struct rxrpc_call *call, struct sk_buff *skb, (test_and_clear_bit(RXRPC_CALL_EV_ACK_LOST, &call->events) || retrans || call->cong_mode == RXRPC_CALL_SLOW_START || - (call->peer->rtt_usage < 3 && sp->hdr.seq & 1) || + (call->peer->rtt_count < 3 && sp->hdr.seq & 1) || ktime_before(ktime_add_ms(call->peer->rtt_last_req, 1000), ktime_get_real()))) whdr.flags |= RXRPC_REQUEST_ACK; @@ -423,13 +423,10 @@ done: if (whdr.flags & RXRPC_REQUEST_ACK) { call->peer->rtt_last_req = skb->tstamp; trace_rxrpc_rtt_tx(call, rxrpc_rtt_tx_data, serial); - if (call->peer->rtt_usage > 1) { + if (call->peer->rtt_count > 1) { unsigned long nowj = jiffies, ack_lost_at; - ack_lost_at = nsecs_to_jiffies(2 * call->peer->rtt); - if (ack_lost_at < 1) - ack_lost_at = 1; - + ack_lost_at = rxrpc_get_rto_backoff(call->peer, retrans); ack_lost_at += nowj; WRITE_ONCE(call->ack_lost_at, ack_lost_at); rxrpc_reduce_call_timer(call, ack_lost_at, nowj, diff --git a/net/rxrpc/peer_event.c b/net/rxrpc/peer_event.c index 923b263c401b..b1449d971883 100644 --- a/net/rxrpc/peer_event.c +++ b/net/rxrpc/peer_event.c @@ -295,52 +295,6 @@ static void rxrpc_distribute_error(struct rxrpc_peer *peer, int error, } } -/* - * Add RTT information to cache. This is called in softirq mode and has - * exclusive access to the peer RTT data. - */ -void rxrpc_peer_add_rtt(struct rxrpc_call *call, enum rxrpc_rtt_rx_trace why, - rxrpc_serial_t send_serial, rxrpc_serial_t resp_serial, - ktime_t send_time, ktime_t resp_time) -{ - struct rxrpc_peer *peer = call->peer; - s64 rtt; - u64 sum = peer->rtt_sum, avg; - u8 cursor = peer->rtt_cursor, usage = peer->rtt_usage; - - rtt = ktime_to_ns(ktime_sub(resp_time, send_time)); - if (rtt < 0) - return; - - spin_lock(&peer->rtt_input_lock); - - /* Replace the oldest datum in the RTT buffer */ - sum -= peer->rtt_cache[cursor]; - sum += rtt; - peer->rtt_cache[cursor] = rtt; - peer->rtt_cursor = (cursor + 1) & (RXRPC_RTT_CACHE_SIZE - 1); - peer->rtt_sum = sum; - if (usage < RXRPC_RTT_CACHE_SIZE) { - usage++; - peer->rtt_usage = usage; - } - - spin_unlock(&peer->rtt_input_lock); - - /* Now recalculate the average */ - if (usage == RXRPC_RTT_CACHE_SIZE) { - avg = sum / RXRPC_RTT_CACHE_SIZE; - } else { - avg = sum; - do_div(avg, usage); - } - - /* Don't need to update this under lock */ - peer->rtt = avg; - trace_rxrpc_rtt_rx(call, why, send_serial, resp_serial, rtt, - usage, avg); -} - /* * Perform keep-alive pings. */ diff --git a/net/rxrpc/peer_object.c b/net/rxrpc/peer_object.c index 64830d8c1fdb..efce27802a74 100644 --- a/net/rxrpc/peer_object.c +++ b/net/rxrpc/peer_object.c @@ -224,6 +224,8 @@ struct rxrpc_peer *rxrpc_alloc_peer(struct rxrpc_local *local, gfp_t gfp) spin_lock_init(&peer->rtt_input_lock); peer->debug_id = atomic_inc_return(&rxrpc_debug_id); + rxrpc_peer_init_rtt(peer); + if (RXRPC_TX_SMSS > 2190) peer->cong_cwnd = 2; else if (RXRPC_TX_SMSS > 1095) @@ -495,14 +497,14 @@ void rxrpc_kernel_get_peer(struct socket *sock, struct rxrpc_call *call, EXPORT_SYMBOL(rxrpc_kernel_get_peer); /** - * rxrpc_kernel_get_rtt - Get a call's peer RTT + * rxrpc_kernel_get_srtt - Get a call's peer smoothed RTT * @sock: The socket on which the call is in progress. * @call: The call to query * - * Get the call's peer RTT. + * Get the call's peer smoothed RTT. */ -u64 rxrpc_kernel_get_rtt(struct socket *sock, struct rxrpc_call *call) +u32 rxrpc_kernel_get_srtt(struct socket *sock, struct rxrpc_call *call) { - return call->peer->rtt; + return call->peer->srtt_us >> 3; } -EXPORT_SYMBOL(rxrpc_kernel_get_rtt); +EXPORT_SYMBOL(rxrpc_kernel_get_srtt); diff --git a/net/rxrpc/proc.c b/net/rxrpc/proc.c index b9d053e42821..8b179e3c802a 100644 --- a/net/rxrpc/proc.c +++ b/net/rxrpc/proc.c @@ -222,7 +222,7 @@ static int rxrpc_peer_seq_show(struct seq_file *seq, void *v) seq_puts(seq, "Proto Local " " Remote " - " Use CW MTU LastUse RTT Rc\n" + " Use CW MTU LastUse RTT RTO\n" ); return 0; } @@ -236,15 +236,15 @@ static int rxrpc_peer_seq_show(struct seq_file *seq, void *v) now = ktime_get_seconds(); seq_printf(seq, "UDP %-47.47s %-47.47s %3u" - " %3u %5u %6llus %12llu %2u\n", + " %3u %5u %6llus %8u %8u\n", lbuff, rbuff, atomic_read(&peer->usage), peer->cong_cwnd, peer->mtu, now - peer->last_tx_at, - peer->rtt, - peer->rtt_cursor); + peer->srtt_us >> 3, + jiffies_to_usecs(peer->rto_j)); return 0; } diff --git a/net/rxrpc/rtt.c b/net/rxrpc/rtt.c new file mode 100644 index 000000000000..928d8b34a3ee --- /dev/null +++ b/net/rxrpc/rtt.c @@ -0,0 +1,195 @@ +// SPDX-License-Identifier: GPL-2.0 +/* RTT/RTO calculation. + * + * Adapted from TCP for AF_RXRPC by David Howells (dhowells@redhat.com) + * + * https://tools.ietf.org/html/rfc6298 + * https://tools.ietf.org/html/rfc1122#section-4.2.3.1 + * http://ccr.sigcomm.org/archive/1995/jan95/ccr-9501-partridge87.pdf + */ + +#include +#include "ar-internal.h" + +#define RXRPC_RTO_MAX ((unsigned)(120 * HZ)) +#define RXRPC_TIMEOUT_INIT ((unsigned)(1*HZ)) /* RFC6298 2.1 initial RTO value */ +#define rxrpc_jiffies32 ((u32)jiffies) /* As rxrpc_jiffies32 */ +#define rxrpc_min_rtt_wlen 300 /* As sysctl_tcp_min_rtt_wlen */ + +static u32 rxrpc_rto_min_us(struct rxrpc_peer *peer) +{ + return 200; +} + +static u32 __rxrpc_set_rto(const struct rxrpc_peer *peer) +{ + return _usecs_to_jiffies((peer->srtt_us >> 3) + peer->rttvar_us); +} + +static u32 rxrpc_bound_rto(u32 rto) +{ + return min(rto, RXRPC_RTO_MAX); +} + +/* + * Called to compute a smoothed rtt estimate. The data fed to this + * routine either comes from timestamps, or from segments that were + * known _not_ to have been retransmitted [see Karn/Partridge + * Proceedings SIGCOMM 87]. The algorithm is from the SIGCOMM 88 + * piece by Van Jacobson. + * NOTE: the next three routines used to be one big routine. + * To save cycles in the RFC 1323 implementation it was better to break + * it up into three procedures. -- erics + */ +static void rxrpc_rtt_estimator(struct rxrpc_peer *peer, long sample_rtt_us) +{ + long m = sample_rtt_us; /* RTT */ + u32 srtt = peer->srtt_us; + + /* The following amusing code comes from Jacobson's + * article in SIGCOMM '88. Note that rtt and mdev + * are scaled versions of rtt and mean deviation. + * This is designed to be as fast as possible + * m stands for "measurement". + * + * On a 1990 paper the rto value is changed to: + * RTO = rtt + 4 * mdev + * + * Funny. This algorithm seems to be very broken. + * These formulae increase RTO, when it should be decreased, increase + * too slowly, when it should be increased quickly, decrease too quickly + * etc. I guess in BSD RTO takes ONE value, so that it is absolutely + * does not matter how to _calculate_ it. Seems, it was trap + * that VJ failed to avoid. 8) + */ + if (srtt != 0) { + m -= (srtt >> 3); /* m is now error in rtt est */ + srtt += m; /* rtt = 7/8 rtt + 1/8 new */ + if (m < 0) { + m = -m; /* m is now abs(error) */ + m -= (peer->mdev_us >> 2); /* similar update on mdev */ + /* This is similar to one of Eifel findings. + * Eifel blocks mdev updates when rtt decreases. + * This solution is a bit different: we use finer gain + * for mdev in this case (alpha*beta). + * Like Eifel it also prevents growth of rto, + * but also it limits too fast rto decreases, + * happening in pure Eifel. + */ + if (m > 0) + m >>= 3; + } else { + m -= (peer->mdev_us >> 2); /* similar update on mdev */ + } + + peer->mdev_us += m; /* mdev = 3/4 mdev + 1/4 new */ + if (peer->mdev_us > peer->mdev_max_us) { + peer->mdev_max_us = peer->mdev_us; + if (peer->mdev_max_us > peer->rttvar_us) + peer->rttvar_us = peer->mdev_max_us; + } + } else { + /* no previous measure. */ + srtt = m << 3; /* take the measured time to be rtt */ + peer->mdev_us = m << 1; /* make sure rto = 3*rtt */ + peer->rttvar_us = max(peer->mdev_us, rxrpc_rto_min_us(peer)); + peer->mdev_max_us = peer->rttvar_us; + } + + peer->srtt_us = max(1U, srtt); +} + +/* + * Calculate rto without backoff. This is the second half of Van Jacobson's + * routine referred to above. + */ +static void rxrpc_set_rto(struct rxrpc_peer *peer) +{ + u32 rto; + + /* 1. If rtt variance happened to be less 50msec, it is hallucination. + * It cannot be less due to utterly erratic ACK generation made + * at least by solaris and freebsd. "Erratic ACKs" has _nothing_ + * to do with delayed acks, because at cwnd>2 true delack timeout + * is invisible. Actually, Linux-2.4 also generates erratic + * ACKs in some circumstances. + */ + rto = __rxrpc_set_rto(peer); + + /* 2. Fixups made earlier cannot be right. + * If we do not estimate RTO correctly without them, + * all the algo is pure shit and should be replaced + * with correct one. It is exactly, which we pretend to do. + */ + + /* NOTE: clamping at RXRPC_RTO_MIN is not required, current algo + * guarantees that rto is higher. + */ + peer->rto_j = rxrpc_bound_rto(rto); +} + +static void rxrpc_ack_update_rtt(struct rxrpc_peer *peer, long rtt_us) +{ + if (rtt_us < 0) + return; + + //rxrpc_update_rtt_min(peer, rtt_us); + rxrpc_rtt_estimator(peer, rtt_us); + rxrpc_set_rto(peer); + + /* RFC6298: only reset backoff on valid RTT measurement. */ + peer->backoff = 0; +} + +/* + * Add RTT information to cache. This is called in softirq mode and has + * exclusive access to the peer RTT data. + */ +void rxrpc_peer_add_rtt(struct rxrpc_call *call, enum rxrpc_rtt_rx_trace why, + rxrpc_serial_t send_serial, rxrpc_serial_t resp_serial, + ktime_t send_time, ktime_t resp_time) +{ + struct rxrpc_peer *peer = call->peer; + s64 rtt_us; + + rtt_us = ktime_to_us(ktime_sub(resp_time, send_time)); + if (rtt_us < 0) + return; + + spin_lock(&peer->rtt_input_lock); + rxrpc_ack_update_rtt(peer, rtt_us); + if (peer->rtt_count < 3) + peer->rtt_count++; + spin_unlock(&peer->rtt_input_lock); + + trace_rxrpc_rtt_rx(call, why, send_serial, resp_serial, + peer->srtt_us >> 3, peer->rto_j); +} + +/* + * Get the retransmission timeout to set in jiffies, backing it off each time + * we retransmit. + */ +unsigned long rxrpc_get_rto_backoff(struct rxrpc_peer *peer, bool retrans) +{ + u64 timo_j; + u8 backoff = READ_ONCE(peer->backoff); + + timo_j = peer->rto_j; + timo_j <<= backoff; + if (retrans && timo_j * 2 <= RXRPC_RTO_MAX) + WRITE_ONCE(peer->backoff, backoff + 1); + + if (timo_j < 1) + timo_j = 1; + + return timo_j; +} + +void rxrpc_peer_init_rtt(struct rxrpc_peer *peer) +{ + peer->rto_j = RXRPC_TIMEOUT_INIT; + peer->mdev_us = jiffies_to_usecs(RXRPC_TIMEOUT_INIT); + peer->backoff = 0; + //minmax_reset(&peer->rtt_min, rxrpc_jiffies32, ~0U); +} diff --git a/net/rxrpc/sendmsg.c b/net/rxrpc/sendmsg.c index 0fcf157aa09f..5e9c43d4a314 100644 --- a/net/rxrpc/sendmsg.c +++ b/net/rxrpc/sendmsg.c @@ -66,15 +66,14 @@ static int rxrpc_wait_for_tx_window_waitall(struct rxrpc_sock *rx, struct rxrpc_call *call) { rxrpc_seq_t tx_start, tx_win; - signed long rtt2, timeout; - u64 rtt; + signed long rtt, timeout; - rtt = READ_ONCE(call->peer->rtt); - rtt2 = nsecs_to_jiffies64(rtt) * 2; - if (rtt2 < 2) - rtt2 = 2; + rtt = READ_ONCE(call->peer->srtt_us) >> 3; + rtt = usecs_to_jiffies(rtt) * 2; + if (rtt < 2) + rtt = 2; - timeout = rtt2; + timeout = rtt; tx_start = READ_ONCE(call->tx_hard_ack); for (;;) { @@ -92,7 +91,7 @@ static int rxrpc_wait_for_tx_window_waitall(struct rxrpc_sock *rx, return -EINTR; if (tx_win != tx_start) { - timeout = rtt2; + timeout = rtt; tx_start = tx_win; } @@ -271,16 +270,9 @@ static int rxrpc_queue_packet(struct rxrpc_sock *rx, struct rxrpc_call *call, _debug("need instant resend %d", ret); rxrpc_instant_resend(call, ix); } else { - unsigned long now = jiffies, resend_at; + unsigned long now = jiffies; + unsigned long resend_at = now + call->peer->rto_j; - if (call->peer->rtt_usage > 1) - resend_at = nsecs_to_jiffies(call->peer->rtt * 3 / 2); - else - resend_at = rxrpc_resend_timeout; - if (resend_at < 1) - resend_at = 1; - - resend_at += now; WRITE_ONCE(call->resend_at, resend_at); rxrpc_reduce_call_timer(call, resend_at, now, rxrpc_timer_set_for_send); diff --git a/net/rxrpc/sysctl.c b/net/rxrpc/sysctl.c index 2bbb38161851..18dade4e6f9a 100644 --- a/net/rxrpc/sysctl.c +++ b/net/rxrpc/sysctl.c @@ -71,15 +71,6 @@ static struct ctl_table rxrpc_sysctl_table[] = { .extra1 = (void *)&one_jiffy, .extra2 = (void *)&max_jiffies, }, - { - .procname = "resend_timeout", - .data = &rxrpc_resend_timeout, - .maxlen = sizeof(unsigned long), - .mode = 0644, - .proc_handler = proc_doulongvec_ms_jiffies_minmax, - .extra1 = (void *)&one_jiffy, - .extra2 = (void *)&max_jiffies, - }, /* Non-time values */ {