diff options
| -rw-r--r-- | include/linux/bpf.h | 1 | ||||
| -rw-r--r-- | include/uapi/linux/bpf.h | 9 | ||||
| -rw-r--r-- | kernel/bpf/core.c | 1 | ||||
| -rw-r--r-- | kernel/bpf/helpers.c | 12 | ||||
| -rw-r--r-- | kernel/bpf/verifier.c | 24 | ||||
| -rw-r--r-- | net/core/filter.c | 2 | ||||
| -rw-r--r-- | tools/include/uapi/linux/bpf.h | 9 | ||||
| -rw-r--r-- | tools/testing/selftests/bpf/bpf_tcp_helpers.h | 16 | ||||
| -rw-r--r-- | tools/testing/selftests/bpf/prog_tests/bpf_tcp_ca.c | 25 | ||||
| -rw-r--r-- | tools/testing/selftests/bpf/progs/bpf_cubic.c | 544 |
10 files changed, 641 insertions, 2 deletions
diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 05d16615054c..a9687861fd7e 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1414,6 +1414,7 @@ extern const struct bpf_func_proto bpf_get_local_storage_proto; extern const struct bpf_func_proto bpf_strtol_proto; extern const struct bpf_func_proto bpf_strtoul_proto; extern const struct bpf_func_proto bpf_tcp_sock_proto; +extern const struct bpf_func_proto bpf_jiffies64_proto; /* Shared helpers among cBPF and eBPF. */ void bpf_user_rnd_init_once(void); diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index e81628eb059c..f1d74a2bd234 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -2886,6 +2886,12 @@ union bpf_attr { * **-EPERM** if no permission to send the *sig*. * * **-EAGAIN** if bpf program can try again. + * + * u64 bpf_jiffies64(void) + * Description + * Obtain the 64bit jiffies + * Return + * The 64 bit jiffies */ #define __BPF_FUNC_MAPPER(FN) \ FN(unspec), \ @@ -3005,7 +3011,8 @@ union bpf_attr { FN(probe_read_user_str), \ FN(probe_read_kernel_str), \ FN(tcp_send_ack), \ - FN(send_signal_thread), + FN(send_signal_thread), \ + FN(jiffies64), /* integer value in 'imm' field of BPF_CALL instruction selects which helper * function eBPF program intends to call diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 29d47aae0dd1..973a20d49749 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -2137,6 +2137,7 @@ const struct bpf_func_proto bpf_map_pop_elem_proto __weak; const struct bpf_func_proto bpf_map_peek_elem_proto __weak; const struct bpf_func_proto bpf_spin_lock_proto __weak; const struct bpf_func_proto bpf_spin_unlock_proto __weak; +const struct bpf_func_proto bpf_jiffies64_proto __weak; const struct bpf_func_proto bpf_get_prandom_u32_proto __weak; const struct bpf_func_proto bpf_get_smp_processor_id_proto __weak; diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index cada974c9f4e..d8b7b110a1c5 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -11,6 +11,7 @@ #include <linux/uidgid.h> #include <linux/filter.h> #include <linux/ctype.h> +#include <linux/jiffies.h> #include "../../lib/kstrtox.h" @@ -312,6 +313,17 @@ void copy_map_value_locked(struct bpf_map *map, void *dst, void *src, preempt_enable(); } +BPF_CALL_0(bpf_jiffies64) +{ + return get_jiffies_64(); +} + +const struct bpf_func_proto bpf_jiffies64_proto = { + .func = bpf_jiffies64, + .gpl_only = false, + .ret_type = RET_INTEGER, +}; + #ifdef CONFIG_CGROUPS BPF_CALL_0(bpf_get_current_cgroup_id) { diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 9fe94f64f0ec..734abaa02123 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -9445,6 +9445,30 @@ static int fixup_bpf_calls(struct bpf_verifier_env *env) goto patch_call_imm; } + if (prog->jit_requested && BITS_PER_LONG == 64 && + insn->imm == BPF_FUNC_jiffies64) { + struct bpf_insn ld_jiffies_addr[2] = { + BPF_LD_IMM64(BPF_REG_0, + (unsigned long)&jiffies), + }; + + insn_buf[0] = ld_jiffies_addr[0]; + insn_buf[1] = ld_jiffies_addr[1]; + insn_buf[2] = BPF_LDX_MEM(BPF_DW, BPF_REG_0, + BPF_REG_0, 0); + cnt = 3; + + new_prog = bpf_patch_insn_data(env, i + delta, insn_buf, + cnt); + if (!new_prog) + return -ENOMEM; + + delta += cnt - 1; + env->prog = prog = new_prog; + insn = new_prog->insnsi + i + delta; + continue; + } + patch_call_imm: fn = env->ops->get_func_proto(insn->imm, env->prog); /* all functions that have prototype and verifier allowed diff --git a/net/core/filter.c b/net/core/filter.c index 17de6747d9e3..4bf3e4aa8a7a 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -5923,6 +5923,8 @@ bpf_base_func_proto(enum bpf_func_id func_id) return &bpf_spin_unlock_proto; case BPF_FUNC_trace_printk: return bpf_get_trace_printk_proto(); + case BPF_FUNC_jiffies64: + return &bpf_jiffies64_proto; default: return NULL; } diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index e81628eb059c..f1d74a2bd234 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -2886,6 +2886,12 @@ union bpf_attr { * **-EPERM** if no permission to send the *sig*. * * **-EAGAIN** if bpf program can try again. + * + * u64 bpf_jiffies64(void) + * Description + * Obtain the 64bit jiffies + * Return + * The 64 bit jiffies */ #define __BPF_FUNC_MAPPER(FN) \ FN(unspec), \ @@ -3005,7 +3011,8 @@ union bpf_attr { FN(probe_read_user_str), \ FN(probe_read_kernel_str), \ FN(tcp_send_ack), \ - FN(send_signal_thread), + FN(send_signal_thread), \ + FN(jiffies64), /* integer value in 'imm' field of BPF_CALL instruction selects which helper * function eBPF program intends to call diff --git a/tools/testing/selftests/bpf/bpf_tcp_helpers.h b/tools/testing/selftests/bpf/bpf_tcp_helpers.h index 6fee732f0297..8f21965ffc6c 100644 --- a/tools/testing/selftests/bpf/bpf_tcp_helpers.h +++ b/tools/testing/selftests/bpf/bpf_tcp_helpers.h @@ -6,13 +6,28 @@ #include <linux/types.h> #include <bpf/bpf_helpers.h> #include <bpf/bpf_core_read.h> +#include "bpf_trace_helpers.h" + +#define BPF_STRUCT_OPS(name, args...) \ +SEC("struct_ops/"#name) \ +BPF_PROG(name, args) + +#define tcp_jiffies32 ((__u32)bpf_jiffies64()) struct sock_common { unsigned char skc_state; } __attribute__((preserve_access_index)); +enum sk_pacing { + SK_PACING_NONE = 0, + SK_PACING_NEEDED = 1, + SK_PACING_FQ = 2, +}; + struct sock { struct sock_common __sk_common; + unsigned long sk_pacing_rate; + __u32 sk_pacing_status; /* see enum sk_pacing */ } __attribute__((preserve_access_index)); struct inet_sock { @@ -54,6 +69,7 @@ struct tcp_sock { __u32 max_packets_out; __u32 lsndtime; __u32 prior_cwnd; + __u64 tcp_mstamp; /* most recent packet received/sent */ } __attribute__((preserve_access_index)); static __always_inline struct inet_connection_sock *inet_csk(const struct sock *sk) diff --git a/tools/testing/selftests/bpf/prog_tests/bpf_tcp_ca.c b/tools/testing/selftests/bpf/prog_tests/bpf_tcp_ca.c index 517318f05b1d..8482bbc67eec 100644 --- a/tools/testing/selftests/bpf/prog_tests/bpf_tcp_ca.c +++ b/tools/testing/selftests/bpf/prog_tests/bpf_tcp_ca.c @@ -4,6 +4,7 @@ #include <linux/err.h> #include <test_progs.h> #include "bpf_dctcp.skel.h" +#include "bpf_cubic.skel.h" #define min(a, b) ((a) < (b) ? (a) : (b)) @@ -158,6 +159,28 @@ done: close(fd); } +static void test_cubic(void) +{ + struct bpf_cubic *cubic_skel; + struct bpf_link *link; + + cubic_skel = bpf_cubic__open_and_load(); + if (CHECK(!cubic_skel, "bpf_cubic__open_and_load", "failed\n")) + return; + + link = bpf_map__attach_struct_ops(cubic_skel->maps.cubic); + if (CHECK(IS_ERR(link), "bpf_map__attach_struct_ops", "err:%ld\n", + PTR_ERR(link))) { + bpf_cubic__destroy(cubic_skel); + return; + } + + do_test("bpf_cubic"); + + bpf_link__destroy(link); + bpf_cubic__destroy(cubic_skel); +} + static void test_dctcp(void) { struct bpf_dctcp *dctcp_skel; @@ -184,4 +207,6 @@ void test_bpf_tcp_ca(void) { if (test__start_subtest("dctcp")) test_dctcp(); + if (test__start_subtest("cubic")) + test_cubic(); } diff --git a/tools/testing/selftests/bpf/progs/bpf_cubic.c b/tools/testing/selftests/bpf/progs/bpf_cubic.c new file mode 100644 index 000000000000..7897c8f4d363 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/bpf_cubic.c @@ -0,0 +1,544 @@ +// SPDX-License-Identifier: GPL-2.0-only + +/* WARNING: This implemenation is not necessarily the same + * as the tcp_cubic.c. The purpose is mainly for testing + * the kernel BPF logic. + * + * Highlights: + * 1. CONFIG_HZ .kconfig map is used. + * 2. In bictcp_update(), calculation is changed to use usec + * resolution (i.e. USEC_PER_JIFFY) instead of using jiffies. + * Thus, usecs_to_jiffies() is not used in the bpf_cubic.c. + * 3. In bitctcp_update() [under tcp_friendliness], the original + * "while (ca->ack_cnt > delta)" loop is changed to the equivalent + * "ca->ack_cnt / delta" operation. + */ + +#include <linux/bpf.h> +#include "bpf_tcp_helpers.h" + +char _license[] SEC("license") = "GPL"; + +#define clamp(val, lo, hi) min((typeof(val))max(val, lo), hi) + +#define BICTCP_BETA_SCALE 1024 /* Scale factor beta calculation + * max_cwnd = snd_cwnd * beta + */ +#define BICTCP_HZ 10 /* BIC HZ 2^10 = 1024 */ + +/* Two methods of hybrid slow start */ +#define HYSTART_ACK_TRAIN 0x1 +#define HYSTART_DELAY 0x2 + +/* Number of delay samples for detecting the increase of delay */ +#define HYSTART_MIN_SAMPLES 8 +#define HYSTART_DELAY_MIN (4000U) /* 4ms */ +#define HYSTART_DELAY_MAX (16000U) /* 16 ms */ +#define HYSTART_DELAY_THRESH(x) clamp(x, HYSTART_DELAY_MIN, HYSTART_DELAY_MAX) + +static int fast_convergence = 1; +static const int beta = 717; /* = 717/1024 (BICTCP_BETA_SCALE) */ +static int initial_ssthresh; +static const int bic_scale = 41; +static int tcp_friendliness = 1; + +static int hystart = 1; +static int hystart_detect = HYSTART_ACK_TRAIN | HYSTART_DELAY; +static int hystart_low_window = 16; +static int hystart_ack_delta_us = 2000; + +static const __u32 cube_rtt_scale = (bic_scale * 10); /* 1024*c/rtt */ +static const __u32 beta_scale = 8*(BICTCP_BETA_SCALE+beta) / 3 + / (BICTCP_BETA_SCALE - beta); +/* calculate the "K" for (wmax-cwnd) = c/rtt * K^3 + * so K = cubic_root( (wmax-cwnd)*rtt/c ) + * the unit of K is bictcp_HZ=2^10, not HZ + * + * c = bic_scale >> 10 + * rtt = 100ms + * + * the following code has been designed and tested for + * cwnd < 1 million packets + * RTT < 100 seconds + * HZ < 1,000,00 (corresponding to 10 nano-second) + */ + +/* 1/c * 2^2*bictcp_HZ * srtt, 2^40 */ +static const __u64 cube_factor = (__u64)(1ull << (10+3*BICTCP_HZ)) + / (bic_scale * 10); + +/* BIC TCP Parameters */ +struct bictcp { + __u32 cnt; /* increase cwnd by 1 after ACKs */ + __u32 last_max_cwnd; /* last maximum snd_cwnd */ + __u32 last_cwnd; /* the last snd_cwnd */ + __u32 last_time; /* time when updated last_cwnd */ + __u32 bic_origin_point;/* origin point of bic function */ + __u32 bic_K; /* time to origin point + from the beginning of the current epoch */ + __u32 delay_min; /* min delay (usec) */ + __u32 epoch_start; /* beginning of an epoch */ + __u32 ack_cnt; /* number of acks */ + __u32 tcp_cwnd; /* estimated tcp cwnd */ + __u16 unused; + __u8 sample_cnt; /* number of samples to decide curr_rtt */ + __u8 found; /* the exit point is found? */ + __u32 round_start; /* beginning of each round */ + __u32 end_seq; /* end_seq of the round */ + __u32 last_ack; /* last time when the ACK spacing is close */ + __u32 curr_rtt; /* the minimum rtt of current round */ +}; + +static inline void bictcp_reset(struct bictcp *ca) +{ + ca->cnt = 0; + ca->last_max_cwnd = 0; + ca->last_cwnd = 0; + ca->last_time = 0; + ca->bic_origin_point = 0; + ca->bic_K = 0; + ca->delay_min = 0; + ca->epoch_start = 0; + ca->ack_cnt = 0; + ca->tcp_cwnd = 0; + ca->found = 0; +} + +extern unsigned long CONFIG_HZ __kconfig; +#define HZ CONFIG_HZ +#define USEC_PER_MSEC 1000UL +#define USEC_PER_SEC 1000000UL +#define USEC_PER_JIFFY (USEC_PER_SEC / HZ) + +static __always_inline __u64 div64_u64(__u64 dividend, __u64 divisor) +{ + return dividend / divisor; +} + +#define div64_ul div64_u64 + +#define BITS_PER_U64 (sizeof(__u64) * 8) +static __always_inline int fls64(__u64 x) +{ + int num = BITS_PER_U64 - 1; + + if (x == 0) + return 0; + + if (!(x & (~0ull << (BITS_PER_U64-32)))) { + num -= 32; + x <<= 32; + } + if (!(x & (~0ull << (BITS_PER_U64-16)))) { + num -= 16; + x <<= 16; + } + if (!(x & (~0ull << (BITS_PER_U64-8)))) { + num -= 8; + x <<= 8; + } + if (!(x & (~0ull << (BITS_PER_U64-4)))) { + num -= 4; + x <<= 4; + } + if (!(x & (~0ull << (BITS_PER_U64-2)))) { + num -= 2; + x <<= 2; + } + if (!(x & (~0ull << (BITS_PER_U64-1)))) + num -= 1; + + return num + 1; +} + +static __always_inline __u32 bictcp_clock_us(const struct sock *sk) +{ + return tcp_sk(sk)->tcp_mstamp; +} + +static __always_inline void bictcp_hystart_reset(struct sock *sk) +{ + struct tcp_sock *tp = tcp_sk(sk); + struct bictcp *ca = inet_csk_ca(sk); + + ca->round_start = ca->last_ack = bictcp_clock_us(sk); + ca->end_seq = tp->snd_nxt; + ca->curr_rtt = ~0U; + ca->sample_cnt = 0; +} + +/* "struct_ops/" prefix is not a requirement + * It will be recognized as BPF_PROG_TYPE_STRUCT_OPS + * as long as it is used in one of the func ptr + * under SEC(".struct_ops"). + */ +SEC("struct_ops/bictcp_init") +void BPF_PROG(bictcp_init, struct sock *sk) +{ + struct bictcp *ca = inet_csk_ca(sk); + + bictcp_reset(ca); + + if (hystart) + bictcp_hystart_reset(sk); + + if (!hystart && initial_ssthresh) + tcp_sk(sk)->snd_ssthresh = initial_ssthresh; +} + +/* No prefix in SEC will also work. + * The remaining tcp-cubic functions have an easier way. + */ +SEC("no-sec-prefix-bictcp_cwnd_event") +void BPF_PROG(bictcp_cwnd_event, struct sock *sk, enum tcp_ca_event event) +{ + if (event == CA_EVENT_TX_START) { + struct bictcp *ca = inet_csk_ca(sk); + __u32 now = tcp_jiffies32; + __s32 delta; + + delta = now - tcp_sk(sk)->lsndtime; + + /* We were application limited (idle) for a while. + * Shift epoch_start to keep cwnd growth to cubic curve. + */ + if (ca->epoch_start && delta > 0) { + ca->epoch_start += delta; + if (after(ca->epoch_start, now)) + ca->epoch_start = now; + } + return; + } +} + +/* + * cbrt(x) MSB values for x MSB values in [0..63]. + * Precomputed then refined by hand - Willy Tarreau + * + * For x in [0..63], + * v = cbrt(x << 18) - 1 + * cbrt(x) = (v[x] + 10) >> 6 + */ +static const __u8 v[] = { + /* 0x00 */ 0, 54, 54, 54, 118, 118, 118, 118, + /* 0x08 */ 123, 129, 134, 138, 143, 147, 151, 156, + /* 0x10 */ 157, 161, 164, 168, 170, 173, 176, 179, + /* 0x18 */ 181, 185, 187, 190, 192, 194, 197, 199, + /* 0x20 */ 200, 202, 204, 206, 209, 211, 213, 215, + /* 0x28 */ 217, 219, 221, 222, 224, 225, 227, 229, + /* 0x30 */ 231, 232, 234, 236, 237, 239, 240, 242, + /* 0x38 */ 244, 245, 246, 248, 250, 251, 252, 254, +}; + +/* calculate the cubic root of x using a table lookup followed by one + * Newton-Raphson iteration. + * Avg err ~= 0.195% + */ +static __always_inline __u32 cubic_root(__u64 a) +{ + __u32 x, b, shift; + + if (a < 64) { + /* a in [0..63] */ + return ((__u32)v[(__u32)a] + 35) >> 6; + } + + b = fls64(a); + b = ((b * 84) >> 8) - 1; + shift = (a >> (b * 3)); + + /* it is needed for verifier's bound check on v */ + if (shift >= 64) + return 0; + + x = ((__u32)(((__u32)v[shift] + 10) << b)) >> 6; + + /* + * Newton-Raphson iteration + * 2 + * x = ( 2 * x + a / x ) / 3 + * k+1 k k + */ + x = (2 * x + (__u32)div64_u64(a, (__u64)x * (__u64)(x - 1))); + x = ((x * 341) >> 10); + return x; +} + +/* + * Compute congestion window to use. + */ +static __always_inline void bictcp_update(struct bictcp *ca, __u32 cwnd, + __u32 acked) +{ + __u32 delta, bic_target, max_cnt; + __u64 offs, t; + + ca->ack_cnt += acked; /* count the number of ACKed packets */ + + if (ca->last_cwnd == cwnd && + (__s32)(tcp_jiffies32 - ca->last_time) <= HZ / 32) + return; + + /* The CUBIC function can update ca->cnt at most once per jiffy. + * On all cwnd reduction events, ca->epoch_start is set to 0, + * which will force a recalculation of ca->cnt. + */ + if (ca->epoch_start && tcp_jiffies32 == ca->last_time) + goto tcp_friendliness; + + ca->last_cwnd = cwnd; + ca->last_time = tcp_jiffies32; + + if (ca->epoch_start == 0) { + ca->epoch_start = tcp_jiffies32; /* record beginning */ + ca->ack_cnt = acked; /* start counting */ + ca->tcp_cwnd = cwnd; /* syn with cubic */ + + if (ca->last_max_cwnd <= cwnd) { + ca->bic_K = 0; + ca->bic_origin_point = cwnd; + } else { + /* Compute new K based on + * (wmax-cwnd) * (srtt>>3 / HZ) / c * 2^(3*bictcp_HZ) + */ + ca->bic_K = cubic_root(cube_factor + * (ca->last_max_cwnd - cwnd)); + ca->bic_origin_point = ca->last_max_cwnd; + } + } + + /* cubic function - calc*/ + /* calculate c * time^3 / rtt, + * while considering overflow in calculation of time^3 + * (so time^3 is done by using 64 bit) + * and without the support of division of 64bit numbers + * (so all divisions are done by using 32 bit) + * also NOTE the unit of those veriables + * time = (t - K) / 2^bictcp_HZ + * c = bic_scale >> 10 + * rtt = (srtt >> 3) / HZ + * !!! The following code does not have overflow problems, + * if the cwnd < 1 million packets !!! + */ + + t = (__s32)(tcp_jiffies32 - ca->epoch_start) * USEC_PER_JIFFY; + t += ca->delay_min; + /* change the unit from usec to bictcp_HZ */ + t <<= BICTCP_HZ; + t /= USEC_PER_SEC; + + if (t < ca->bic_K) /* t - K */ + offs = ca->bic_K - t; + else + offs = t - ca->bic_K; + + /* c/rtt * (t-K)^3 */ + delta = (cube_rtt_scale * offs * offs * offs) >> (10+3*BICTCP_HZ); + if (t < ca->bic_K) /* below origin*/ + bic_target = ca->bic_origin_point - delta; + else /* above origin*/ + bic_target = ca->bic_origin_point + delta; + + /* cubic function - calc bictcp_cnt*/ + if (bic_target > cwnd) { + ca->cnt = cwnd / (bic_target - cwnd); + } else { + ca->cnt = 100 * cwnd; /* very small increment*/ + } + + /* + * The initial growth of cubic function may be too conservative + * when the available bandwidth is still unknown. + */ + if (ca->last_max_cwnd == 0 && ca->cnt > 20) + ca->cnt = 20; /* increase cwnd 5% per RTT */ + +tcp_friendliness: + /* TCP Friendly */ + if (tcp_friendliness) { + __u32 scale = beta_scale; + __u32 n; + + /* update tcp cwnd */ + delta = (cwnd * scale) >> 3; + if (ca->ack_cnt > delta && delta) { + n = ca->ack_cnt / delta; + ca->ack_cnt -= n * delta; + ca->tcp_cwnd += n; + } + + if (ca->tcp_cwnd > cwnd) { /* if bic is slower than tcp */ + delta = ca->tcp_cwnd - cwnd; + max_cnt = cwnd / delta; + if (ca->cnt > max_cnt) + ca->cnt = max_cnt; + } + } + + /* The maximum rate of cwnd increase CUBIC allows is 1 packet per + * 2 packets ACKed, meaning cwnd grows at 1.5x per RTT. + */ + ca->cnt = max(ca->cnt, 2U); +} + +/* Or simply use the BPF_STRUCT_OPS to avoid the SEC boiler plate. */ +void BPF_STRUCT_OPS(bictcp_cong_avoid, struct sock *sk, __u32 ack, __u32 acked) +{ + struct tcp_sock *tp = tcp_sk(sk); + struct bictcp *ca = inet_csk_ca(sk); + + if (!tcp_is_cwnd_limited(sk)) + return; + + if (tcp_in_slow_start(tp)) { + if (hystart && after(ack, ca->end_seq)) + bictcp_hystart_reset(sk); + acked = tcp_slow_start(tp, acked); + if (!acked) + return; + } + bictcp_update(ca, tp->snd_cwnd, acked); + tcp_cong_avoid_ai(tp, ca->cnt, acked); +} + +__u32 BPF_STRUCT_OPS(bictcp_recalc_ssthresh, struct sock *sk) +{ + const struct tcp_sock *tp = tcp_sk(sk); + struct bictcp *ca = inet_csk_ca(sk); + + ca->epoch_start = 0; /* end of epoch */ + + /* Wmax and fast convergence */ + if (tp->snd_cwnd < ca->last_max_cwnd && fast_convergence) + ca->last_max_cwnd = (tp->snd_cwnd * (BICTCP_BETA_SCALE + beta)) + / (2 * BICTCP_BETA_SCALE); + else + ca->last_max_cwnd = tp->snd_cwnd; + + return max((tp->snd_cwnd * beta) / BICTCP_BETA_SCALE, 2U); +} + +void BPF_STRUCT_OPS(bictcp_state, struct sock *sk, __u8 new_state) +{ + if (new_state == TCP_CA_Loss) { + bictcp_reset(inet_csk_ca(sk)); + bictcp_hystart_reset(sk); + } +} + +#define GSO_MAX_SIZE 65536 + +/* Account for TSO/GRO delays. + * Otherwise short RTT flows could get too small ssthresh, since during + * slow start we begin with small TSO packets and ca->delay_min would + * not account for long aggregation delay when TSO packets get bigger. + * Ideally even with a very small RTT we would like to have at least one + * TSO packet being sent and received by GRO, and another one in qdisc layer. + * We apply another 100% factor because @rate is doubled at this point. + * We cap the cushion to 1ms. + */ +static __always_inline __u32 hystart_ack_delay(struct sock *sk) +{ + unsigned long rate; + + rate = sk->sk_pacing_rate; + if (!rate) + return 0; + return min((__u64)USEC_PER_MSEC, + div64_ul((__u64)GSO_MAX_SIZE * 4 * USEC_PER_SEC, rate)); +} + +static __always_inline void hystart_update(struct sock *sk, __u32 delay) +{ + struct tcp_sock *tp = tcp_sk(sk); + struct bictcp *ca = inet_csk_ca(sk); + __u32 threshold; + + if (hystart_detect & HYSTART_ACK_TRAIN) { + __u32 now = bictcp_clock_us(sk); + + /* first detection parameter - ack-train detection */ + if ((__s32)(now - ca->last_ack) <= hystart_ack_delta_us) { + ca->last_ack = now; + + threshold = ca->delay_min + hystart_ack_delay(sk); + + /* Hystart ack train triggers if we get ack past + * ca->delay_min/2. + * Pacing might have delayed packets up to RTT/2 + * during slow start. + */ + if (sk->sk_pacing_status == SK_PACING_NONE) + threshold >>= 1; + + if ((__s32)(now - ca->round_start) > threshold) { + ca->found = 1; + tp->snd_ssthresh = tp->snd_cwnd; + } + } + } + + if (hystart_detect & HYSTART_DELAY) { + /* obtain the minimum delay of more than sampling packets */ + if (ca->sample_cnt < HYSTART_MIN_SAMPLES) { + if (ca->curr_rtt > delay) + ca->curr_rtt = delay; + + ca->sample_cnt++; + } else { + if (ca->curr_rtt > ca->delay_min + + HYSTART_DELAY_THRESH(ca->delay_min >> 3)) { + ca->found = 1; + tp->snd_ssthresh = tp->snd_cwnd; + } + } + } +} + +void BPF_STRUCT_OPS(bictcp_acked, struct sock *sk, + const struct ack_sample *sample) +{ + const struct tcp_sock *tp = tcp_sk(sk); + struct bictcp *ca = inet_csk_ca(sk); + __u32 delay; + + /* Some calls are for duplicates without timetamps */ + if (sample->rtt_us < 0) + return; + + /* Discard delay samples right after fast recovery */ + if (ca->epoch_start && (__s32)(tcp_jiffies32 - ca->epoch_start) < HZ) + return; + + delay = sample->rtt_us; + if (delay == 0) + delay = 1; + + /* first time call or link delay decreases */ + if (ca->delay_min == 0 || ca->delay_min > delay) + ca->delay_min = delay; + + /* hystart triggers when cwnd is larger than some threshold */ + if (!ca->found && tcp_in_slow_start(tp) && hystart && + tp->snd_cwnd >= hystart_low_window) + hystart_update(sk, delay); +} + +__u32 BPF_STRUCT_OPS(tcp_reno_undo_cwnd, struct sock *sk) +{ + const struct tcp_sock *tp = tcp_sk(sk); + + return max(tp->snd_cwnd, tp->prior_cwnd); +} + +SEC(".struct_ops") +struct tcp_congestion_ops cubic = { + .init = (void *)bictcp_init, + .ssthresh = (void *)bictcp_recalc_ssthresh, + .cong_avoid = (void *)bictcp_cong_avoid, + .set_state = (void *)bictcp_state, + .undo_cwnd = (void *)tcp_reno_undo_cwnd, + .cwnd_event = (void *)bictcp_cwnd_event, + .pkts_acked = (void *)bictcp_acked, + .name = "bpf_cubic", +}; |