samples/bpf: add sample program that periodically dumps TCP stats (39533884) · Commits · 戴 / test

Uses new RTT callback to dump stats every second. $ mkdir -p /tmp/cgroupv2 $ mount -t cgroup2 none /tmp/cgroupv2 $ mkdir -p /tmp/cgroupv2/foo $ echo $$ >> /tmp/cgroupv2/foo/cgroup.procs $ bpftool prog load ./tcp_dumpstats_kern.o /sys/fs/bpf/tcp_prog $ bpftool cgroup attach /tmp/cgroupv2/foo sock_ops pinned /sys/fs/bpf/tcp_prog $ bpftool prog tracelog $ # run neper/netperf/etc Used neper to compare performance with and without this program attached and didn't see any noticeable performance impact. Sample output: <idle>-0 [015] ..s. 2074.128800: 0: dsack_dups=0 delivered=242526 <idle>-0 [015] ..s. 2074.128808: 0: delivered_ce=0 icsk_retransmits=0 <idle>-0 [015] ..s. 2075.130133: 0: dsack_dups=0 delivered=323599 <idle>-0 [015] ..s. 2075.130138: 0: delivered_ce=0 icsk_retransmits=0 <idle>-0 [005] .Ns. 2076.131440: 0: dsack_dups=0 delivered=404648 <idle>-0 [005] .Ns. 2076.131447: 0: delivered_ce=0 icsk_retransmits=0 Cc: Eric Dumazet <edumazet@google.com> Cc: Priyaranjan Jha <priyarjha@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Soheil Hassas Yeganeh <soheil@google.com> Acked-by:

Soheil Hassas Yeganeh <soheil@google.com> Acked-by:

Yuchung Cheng <ycheng@google.com> Signed-off-by:

Stanislav Fomichev <sdf@google.com> Signed-off-by:

Daniel Borkmann <daniel@iogearbox.net>

samples/bpf/Makefile

+1 −0

Original line number	Diff line number	Diff line
		@@ -154,6 +154,7 @@ always += tcp_iw_kern.o
		always += tcp_clamp_kern.o
		always += tcp_basertt_kern.o
		always += tcp_tos_reflect_kern.o
		always += tcp_dumpstats_kern.o
		always += xdp_redirect_kern.o
		always += xdp_redirect_map_kern.o
		always += xdp_redirect_cpu_kern.o

samples/bpf/tcp_dumpstats_kern.c

0 → 100644

+68 −0

Original line number	Diff line number	Diff line
		// SPDX-License-Identifier: GPL-2.0
		/* Refer to samples/bpf/tcp_bpf.readme for the instructions on
		* how to run this sample program.
		*/
		#include <linux/bpf.h>

		#include "bpf_helpers.h"
		#include "bpf_endian.h"

		#define INTERVAL 1000000000ULL

		int _version SEC("version") = 1;
		char _license[] SEC("license") = "GPL";

		struct {
		__u32 type;
		__u32 map_flags;
		int *key;
		__u64 *value;
		} bpf_next_dump SEC(".maps") = {
		.type = BPF_MAP_TYPE_SK_STORAGE,
		.map_flags = BPF_F_NO_PREALLOC,
		};

		SEC("sockops")
		int _sockops(struct bpf_sock_ops *ctx)
		{
		struct bpf_tcp_sock *tcp_sk;
		struct bpf_sock *sk;
		__u64 *next_dump;
		__u64 now;

		switch (ctx->op) {
		case BPF_SOCK_OPS_TCP_CONNECT_CB:
		bpf_sock_ops_cb_flags_set(ctx, BPF_SOCK_OPS_RTT_CB_FLAG);
		return 1;
		case BPF_SOCK_OPS_RTT_CB:
		break;
		default:
		return 1;
		}

		sk = ctx->sk;
		if (!sk)
		return 1;

		next_dump = bpf_sk_storage_get(&bpf_next_dump, sk, 0,
		BPF_SK_STORAGE_GET_F_CREATE);
		if (!next_dump)
		return 1;

		now = bpf_ktime_get_ns();
		if (now < *next_dump)
		return 1;

		tcp_sk = bpf_tcp_sock(sk);
		if (!tcp_sk)
		return 1;

		*next_dump = now + INTERVAL;

		bpf_printk("dsack_dups=%u delivered=%u\n",
		tcp_sk->dsack_dups, tcp_sk->delivered);
		bpf_printk("delivered_ce=%u icsk_retransmits=%u\n",
		tcp_sk->delivered_ce, tcp_sk->icsk_retransmits);

		return 1;
		}

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