diff options
| -rw-r--r-- | include/linux/tcp.h | 2 | ||||
| -rw-r--r-- | include/net/sock.h | 9 | ||||
| -rw-r--r-- | include/net/tcp.h | 3 | ||||
| -rw-r--r-- | net/core/sock.c | 4 | ||||
| -rw-r--r-- | net/ipv4/tcp_bbr.c | 9 | ||||
| -rw-r--r-- | net/ipv4/tcp_output.c | 80 | ||||
| -rw-r--r-- | net/ipv4/tcp_timer.c | 3 | ||||
| -rw-r--r-- | net/sched/sch_fq.c | 8 |
8 files changed, 113 insertions, 5 deletions
diff --git a/include/linux/tcp.h b/include/linux/tcp.h index b6d5adce..22854f0 100644 --- a/include/linux/tcp.h +++ b/include/linux/tcp.h @@ -293,6 +293,8 @@ struct tcp_sock { u32 sacked_out; /* SACK'd packets */ u32 fackets_out; /* FACK'd packets */ + struct hrtimer pacing_timer; + /* from STCP, retrans queue hinting */ struct sk_buff* lost_skb_hint; struct sk_buff *retransmit_skb_hint; diff --git a/include/net/sock.h b/include/net/sock.h index 42264035..3467d9e 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -253,6 +253,7 @@ struct sock_common { * @sk_ll_usec: usecs to busypoll when there is no data * @sk_allocation: allocation mode * @sk_pacing_rate: Pacing rate (if supported by transport/packet scheduler) + * @sk_pacing_status: Pacing status (requested, handled by sch_fq) * @sk_max_pacing_rate: Maximum pacing rate (%SO_MAX_PACING_RATE) * @sk_sndbuf: size of send buffer in bytes * @sk_padding: unused element for alignment @@ -396,7 +397,7 @@ struct sock { __s32 sk_peek_off; int sk_write_pending; __u32 sk_dst_pending_confirm; - /* Note: 32bit hole on 64bit arches */ + u32 sk_pacing_status; /* see enum sk_pacing */ long sk_sndtimeo; struct timer_list sk_timer; __u32 sk_priority; @@ -475,6 +476,12 @@ struct sock { struct rcu_head sk_rcu; }; +enum sk_pacing { + SK_PACING_NONE = 0, + SK_PACING_NEEDED = 1, + SK_PACING_FQ = 2, +}; + #define __sk_user_data(sk) ((*((void __rcu **)&(sk)->sk_user_data))) #define rcu_dereference_sk_user_data(sk) rcu_dereference(__sk_user_data((sk))) diff --git a/include/net/tcp.h b/include/net/tcp.h index 38a7427..b4dc93d 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -574,6 +574,7 @@ void tcp_fin(struct sock *sk); void tcp_init_xmit_timers(struct sock *); static inline void tcp_clear_xmit_timers(struct sock *sk) { + hrtimer_cancel(&tcp_sk(sk)->pacing_timer); inet_csk_clear_xmit_timers(sk); } @@ -1945,4 +1946,6 @@ static inline void tcp_listendrop(const struct sock *sk) __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS); } +enum hrtimer_restart tcp_pace_kick(struct hrtimer *timer); + #endif /* _TCP_H */ diff --git a/net/core/sock.c b/net/core/sock.c index e43e71d..93d011e 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -1041,6 +1041,10 @@ set_rcvbuf: #endif case SO_MAX_PACING_RATE: + if (val != ~0U) + cmpxchg(&sk->sk_pacing_status, + SK_PACING_NONE, + SK_PACING_NEEDED); sk->sk_max_pacing_rate = val; sk->sk_pacing_rate = min(sk->sk_pacing_rate, sk->sk_max_pacing_rate); diff --git a/net/ipv4/tcp_bbr.c b/net/ipv4/tcp_bbr.c index b89bce4..92b045c 100644 --- a/net/ipv4/tcp_bbr.c +++ b/net/ipv4/tcp_bbr.c @@ -52,10 +52,9 @@ * There is a public e-mail list for discussing BBR development and testing: * https://groups.google.com/forum/#!forum/bbr-dev * - * NOTE: BBR *must* be used with the fq qdisc ("man tc-fq") with pacing enabled, - * since pacing is integral to the BBR design and implementation. - * BBR without pacing would not function properly, and may incur unnecessary - * high packet loss rates. + * NOTE: BBR might be used with the fq qdisc ("man tc-fq") with pacing enabled, + * otherwise TCP stack falls back to an internal pacing using one high + * resolution timer per TCP socket and may use more resources. */ #include <linux/module.h> #include <net/tcp.h> @@ -830,6 +829,8 @@ static void bbr_init(struct sock *sk) bbr->cycle_idx = 0; bbr_reset_lt_bw_sampling(sk); bbr_reset_startup_mode(sk); + + cmpxchg(&sk->sk_pacing_status, SK_PACING_NONE, SK_PACING_NEEDED); } static u32 bbr_sndbuf_expand(struct sock *sk) diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 4858e19..a32172d 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -904,6 +904,72 @@ out: sk_free(sk); } +/* Note: Called under hard irq. + * We can not call TCP stack right away. + */ +enum hrtimer_restart tcp_pace_kick(struct hrtimer *timer) +{ + struct tcp_sock *tp = container_of(timer, struct tcp_sock, pacing_timer); + struct sock *sk = (struct sock *)tp; + unsigned long nval, oval; + + for (oval = READ_ONCE(sk->sk_tsq_flags);; oval = nval) { + struct tsq_tasklet *tsq; + bool empty; + + if (oval & TSQF_QUEUED) + break; + + nval = (oval & ~TSQF_THROTTLED) | TSQF_QUEUED | TCPF_TSQ_DEFERRED; + nval = cmpxchg(&sk->sk_tsq_flags, oval, nval); + if (nval != oval) + continue; + + if (!atomic_inc_not_zero(&sk->sk_wmem_alloc)) + break; + /* queue this socket to tasklet queue */ + tsq = this_cpu_ptr(&tsq_tasklet); + empty = list_empty(&tsq->head); + list_add(&tp->tsq_node, &tsq->head); + if (empty) + tasklet_schedule(&tsq->tasklet); + break; + } + return HRTIMER_NORESTART; +} + +/* BBR congestion control needs pacing. + * Same remark for SO_MAX_PACING_RATE. + * sch_fq packet scheduler is efficiently handling pacing, + * but is not always installed/used. + * Return true if TCP stack should pace packets itself. + */ +static bool tcp_needs_internal_pacing(const struct sock *sk) +{ + return smp_load_acquire(&sk->sk_pacing_status) == SK_PACING_NEEDED; +} + +static void tcp_internal_pacing(struct sock *sk, const struct sk_buff *skb) +{ + u64 len_ns; + u32 rate; + + if (!tcp_needs_internal_pacing(sk)) + return; + rate = sk->sk_pacing_rate; + if (!rate || rate == ~0U) + return; + + /* Should account for header sizes as sch_fq does, + * but lets make things simple. + */ + len_ns = (u64)skb->len * NSEC_PER_SEC; + do_div(len_ns, rate); + hrtimer_start(&tcp_sk(sk)->pacing_timer, + ktime_add_ns(ktime_get(), len_ns), + HRTIMER_MODE_ABS_PINNED); +} + /* This routine actually transmits TCP packets queued in by * tcp_do_sendmsg(). This is used by both the initial * transmission and possible later retransmissions. @@ -1034,6 +1100,7 @@ static int tcp_transmit_skb(struct sock *sk, struct sk_buff *skb, int clone_it, if (skb->len != tcp_header_size) { tcp_event_data_sent(tp, sk); tp->data_segs_out += tcp_skb_pcount(skb); + tcp_internal_pacing(sk, skb); } if (after(tcb->end_seq, tp->snd_nxt) || tcb->seq == tcb->end_seq) @@ -2086,6 +2153,12 @@ static int tcp_mtu_probe(struct sock *sk) return -1; } +static bool tcp_pacing_check(const struct sock *sk) +{ + return tcp_needs_internal_pacing(sk) && + hrtimer_active(&tcp_sk(sk)->pacing_timer); +} + /* TCP Small Queues : * Control number of packets in qdisc/devices to two packets / or ~1 ms. * (These limits are doubled for retransmits) @@ -2210,6 +2283,9 @@ static bool tcp_write_xmit(struct sock *sk, unsigned int mss_now, int nonagle, while ((skb = tcp_send_head(sk))) { unsigned int limit; + if (tcp_pacing_check(sk)) + break; + tso_segs = tcp_init_tso_segs(skb, mss_now); BUG_ON(!tso_segs); @@ -2878,6 +2954,10 @@ void tcp_xmit_retransmit_queue(struct sock *sk) if (skb == tcp_send_head(sk)) break; + + if (tcp_pacing_check(sk)) + break; + /* we could do better than to assign each time */ if (!hole) tp->retransmit_skb_hint = skb; diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c index 1467254..86934bc 100644 --- a/net/ipv4/tcp_timer.c +++ b/net/ipv4/tcp_timer.c @@ -710,4 +710,7 @@ void tcp_init_xmit_timers(struct sock *sk) { inet_csk_init_xmit_timers(sk, &tcp_write_timer, &tcp_delack_timer, &tcp_keepalive_timer); + hrtimer_init(&tcp_sk(sk)->pacing_timer, CLOCK_MONOTONIC, + HRTIMER_MODE_ABS_PINNED); + tcp_sk(sk)->pacing_timer.function = tcp_pace_kick; } diff --git a/net/sched/sch_fq.c b/net/sched/sch_fq.c index b488721..147fde7 100644 --- a/net/sched/sch_fq.c +++ b/net/sched/sch_fq.c @@ -390,9 +390,17 @@ static int fq_enqueue(struct sk_buff *skb, struct Qdisc *sch, q->stat_tcp_retrans++; qdisc_qstats_backlog_inc(sch, skb); if (fq_flow_is_detached(f)) { + struct sock *sk = skb->sk; + fq_flow_add_tail(&q->new_flows, f); if (time_after(jiffies, f->age + q->flow_refill_delay)) f->credit = max_t(u32, f->credit, q->quantum); + if (sk && q->rate_enable) { + if (unlikely(smp_load_acquire(&sk->sk_pacing_status) != + SK_PACING_FQ)) + smp_store_release(&sk->sk_pacing_status, + SK_PACING_FQ); + } q->inactive_flows--; } |
