diff options
Diffstat (limited to 'tools/testing/selftests/bpf/progs/bpf_cc_cubic.c')
| -rw-r--r-- | tools/testing/selftests/bpf/progs/bpf_cc_cubic.c | 189 |
1 files changed, 189 insertions, 0 deletions
diff --git a/tools/testing/selftests/bpf/progs/bpf_cc_cubic.c b/tools/testing/selftests/bpf/progs/bpf_cc_cubic.c new file mode 100644 index 000000000000..1654a530aa3d --- /dev/null +++ b/tools/testing/selftests/bpf/progs/bpf_cc_cubic.c @@ -0,0 +1,189 @@ +// SPDX-License-Identifier: GPL-2.0-only + +/* Highlights: + * 1. The major difference between this bpf program and tcp_cubic.c + * is that this bpf program relies on `cong_control` rather than + * `cong_avoid` in the struct tcp_congestion_ops. + * 2. Logic such as tcp_cwnd_reduction, tcp_cong_avoid, and + * tcp_update_pacing_rate is bypassed when `cong_control` is + * defined, so moving these logic to `cong_control`. + * 3. WARNING: This bpf program is NOT the same as tcp_cubic.c. + * The main purpose is to show use cases of the arguments in + * `cong_control`. For simplicity's sake, it reuses tcp cubic's + * kernel functions. + */ + +#include "bpf_tracing_net.h" +#include <bpf/bpf_helpers.h> +#include <bpf/bpf_tracing.h> + +#define USEC_PER_SEC 1000000UL +#define TCP_PACING_SS_RATIO (200) +#define TCP_PACING_CA_RATIO (120) +#define TCP_REORDERING (12) + +#define min(a, b) ((a) < (b) ? (a) : (b)) +#define max(a, b) ((a) > (b) ? (a) : (b)) +#define after(seq2, seq1) before(seq1, seq2) + +extern void cubictcp_init(struct sock *sk) __ksym; +extern void cubictcp_cwnd_event(struct sock *sk, enum tcp_ca_event event) __ksym; +extern __u32 cubictcp_recalc_ssthresh(struct sock *sk) __ksym; +extern void cubictcp_state(struct sock *sk, __u8 new_state) __ksym; +extern __u32 tcp_reno_undo_cwnd(struct sock *sk) __ksym; +extern void cubictcp_acked(struct sock *sk, const struct ack_sample *sample) __ksym; +extern void cubictcp_cong_avoid(struct sock *sk, __u32 ack, __u32 acked) __ksym; + +static bool before(__u32 seq1, __u32 seq2) +{ + return (__s32)(seq1-seq2) < 0; +} + +static __u64 div64_u64(__u64 dividend, __u64 divisor) +{ + return dividend / divisor; +} + +static void tcp_update_pacing_rate(struct sock *sk) +{ + const struct tcp_sock *tp = tcp_sk(sk); + __u64 rate; + + /* set sk_pacing_rate to 200 % of current rate (mss * cwnd / srtt) */ + rate = (__u64)tp->mss_cache * ((USEC_PER_SEC / 100) << 3); + + /* current rate is (cwnd * mss) / srtt + * In Slow Start [1], set sk_pacing_rate to 200 % the current rate. + * In Congestion Avoidance phase, set it to 120 % the current rate. + * + * [1] : Normal Slow Start condition is (tp->snd_cwnd < tp->snd_ssthresh) + * If snd_cwnd >= (tp->snd_ssthresh / 2), we are approaching + * end of slow start and should slow down. + */ + if (tp->snd_cwnd < tp->snd_ssthresh / 2) + rate *= TCP_PACING_SS_RATIO; + else + rate *= TCP_PACING_CA_RATIO; + + rate *= max(tp->snd_cwnd, tp->packets_out); + + if (tp->srtt_us) + rate = div64_u64(rate, (__u64)tp->srtt_us); + + sk->sk_pacing_rate = min(rate, sk->sk_max_pacing_rate); +} + +static void tcp_cwnd_reduction(struct sock *sk, int newly_acked_sacked, + int newly_lost, int flag) +{ + struct tcp_sock *tp = tcp_sk(sk); + int sndcnt = 0; + __u32 pkts_in_flight = tp->packets_out - (tp->sacked_out + tp->lost_out) + tp->retrans_out; + int delta = tp->snd_ssthresh - pkts_in_flight; + + if (newly_acked_sacked <= 0 || !tp->prior_cwnd) + return; + + __u32 prr_delivered = tp->prr_delivered + newly_acked_sacked; + + if (delta < 0) { + __u64 dividend = + (__u64)tp->snd_ssthresh * prr_delivered + tp->prior_cwnd - 1; + sndcnt = (__u32)div64_u64(dividend, (__u64)tp->prior_cwnd) - tp->prr_out; + } else { + sndcnt = max(prr_delivered - tp->prr_out, newly_acked_sacked); + if (flag & FLAG_SND_UNA_ADVANCED && !newly_lost) + sndcnt++; + sndcnt = min(delta, sndcnt); + } + /* Force a fast retransmit upon entering fast recovery */ + sndcnt = max(sndcnt, (tp->prr_out ? 0 : 1)); + tp->snd_cwnd = pkts_in_flight + sndcnt; +} + +/* Decide wheather to run the increase function of congestion control. */ +static bool tcp_may_raise_cwnd(const struct sock *sk, const int flag) +{ + if (tcp_sk(sk)->reordering > TCP_REORDERING) + return flag & FLAG_FORWARD_PROGRESS; + + return flag & FLAG_DATA_ACKED; +} + +SEC("struct_ops") +void BPF_PROG(bpf_cubic_init, struct sock *sk) +{ + cubictcp_init(sk); +} + +SEC("struct_ops") +void BPF_PROG(bpf_cubic_cwnd_event, struct sock *sk, enum tcp_ca_event event) +{ + cubictcp_cwnd_event(sk, event); +} + +SEC("struct_ops") +void BPF_PROG(bpf_cubic_cong_control, struct sock *sk, __u32 ack, int flag, + const struct rate_sample *rs) +{ + struct tcp_sock *tp = tcp_sk(sk); + + if (((1<<TCP_CA_CWR) | (1<<TCP_CA_Recovery)) & + (1 << inet_csk(sk)->icsk_ca_state)) { + /* Reduce cwnd if state mandates */ + tcp_cwnd_reduction(sk, rs->acked_sacked, rs->losses, flag); + + if (!before(tp->snd_una, tp->high_seq)) { + /* Reset cwnd to ssthresh in CWR or Recovery (unless it's undone) */ + if (tp->snd_ssthresh < TCP_INFINITE_SSTHRESH && + inet_csk(sk)->icsk_ca_state == TCP_CA_CWR) { + tp->snd_cwnd = tp->snd_ssthresh; + tp->snd_cwnd_stamp = tcp_jiffies32; + } + } + } else if (tcp_may_raise_cwnd(sk, flag)) { + /* Advance cwnd if state allows */ + cubictcp_cong_avoid(sk, ack, rs->acked_sacked); + tp->snd_cwnd_stamp = tcp_jiffies32; + } + + tcp_update_pacing_rate(sk); +} + +SEC("struct_ops") +__u32 BPF_PROG(bpf_cubic_recalc_ssthresh, struct sock *sk) +{ + return cubictcp_recalc_ssthresh(sk); +} + +SEC("struct_ops") +void BPF_PROG(bpf_cubic_state, struct sock *sk, __u8 new_state) +{ + cubictcp_state(sk, new_state); +} + +SEC("struct_ops") +void BPF_PROG(bpf_cubic_acked, struct sock *sk, const struct ack_sample *sample) +{ + cubictcp_acked(sk, sample); +} + +SEC("struct_ops") +__u32 BPF_PROG(bpf_cubic_undo_cwnd, struct sock *sk) +{ + return tcp_reno_undo_cwnd(sk); +} + +SEC(".struct_ops") +struct tcp_congestion_ops cc_cubic = { + .init = (void *)bpf_cubic_init, + .ssthresh = (void *)bpf_cubic_recalc_ssthresh, + .cong_control = (void *)bpf_cubic_cong_control, + .set_state = (void *)bpf_cubic_state, + .undo_cwnd = (void *)bpf_cubic_undo_cwnd, + .cwnd_event = (void *)bpf_cubic_cwnd_event, + .pkts_acked = (void *)bpf_cubic_acked, + .name = "bpf_cc_cubic", +}; + +char _license[] SEC("license") = "GPL"; |