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samples/bpf: add sample program that periodically dumps TCP stats

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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>
This commit is contained in:
Stanislav Fomichev 2019-07-02 09:14:02 -07:00 committed by Daniel Borkmann
parent b55873984d
commit 395338843d
2 changed files with 69 additions and 0 deletions
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1
samples/bpf/Makefile
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@ -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

68
samples/bpf/tcp_dumpstats_kern.c Normal file
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@ -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 <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;
}