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authorStanislav Fomichev <sdf@google.com>2019-07-02 16:14:02 (GMT)
committerDaniel Borkmann <daniel@iogearbox.net>2019-07-03 14:52:02 (GMT)
commit395338843de1e47f6876e58adfe75b6483f96fff (patch)
tree9d580787375a25bf8823d73e72be574b9059f056 /samples
parentb55873984dab0eda6db00d19db4c43dce5c11d98 (diff)
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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: <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>
Diffstat (limited to 'samples')
-rw-r--r--samples/bpf/Makefile1
-rw-r--r--samples/bpf/tcp_dumpstats_kern.c68
2 files changed, 69 insertions, 0 deletions
diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
index 3564041..f90daad 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 0000000..8557913
--- /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 <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;
+}