From 395338843de1e47f6876e58adfe75b6483f96fff Mon Sep 17 00:00:00 2001 From: Stanislav Fomichev Date: Tue, 2 Jul 2019 09:14:02 -0700 Subject: samples/bpf: add sample program that periodically dumps TCP stats 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: -0 [015] ..s. 2074.128800: 0: dsack_dups=0 delivered=242526 -0 [015] ..s. 2074.128808: 0: delivered_ce=0 icsk_retransmits=0 -0 [015] ..s. 2075.130133: 0: dsack_dups=0 delivered=323599 -0 [015] ..s. 2075.130138: 0: delivered_ce=0 icsk_retransmits=0 -0 [005] .Ns. 2076.131440: 0: dsack_dups=0 delivered=404648 -0 [005] .Ns. 2076.131447: 0: delivered_ce=0 icsk_retransmits=0 Cc: Eric Dumazet Cc: Priyaranjan Jha Cc: Yuchung Cheng Cc: Soheil Hassas Yeganeh Acked-by: Soheil Hassas Yeganeh Acked-by: Yuchung Cheng Signed-off-by: Stanislav Fomichev Signed-off-by: Daniel Borkmann --- samples/bpf/Makefile | 1 + samples/bpf/tcp_dumpstats_kern.c | 68 ++++++++++++++++++++++++++++++++++++++++ 2 files changed, 69 insertions(+) create mode 100644 samples/bpf/tcp_dumpstats_kern.c diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile index 35640414ebb3..f90daadfbc89 100644 --- a/samples/bpf/Makefile +++ b/samples/bpf/Makefile @@ -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 diff --git a/samples/bpf/tcp_dumpstats_kern.c b/samples/bpf/tcp_dumpstats_kern.c new file mode 100644 index 000000000000..8557913106a0 --- /dev/null +++ b/samples/bpf/tcp_dumpstats_kern.c @@ -0,0 +1,68 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Refer to samples/bpf/tcp_bpf.readme for the instructions on + * how to run this sample program. + */ +#include + +#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; +} -- cgit v1.2.3