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authorLawrence Brakmo <brakmo@fb.com>2017-06-30 20:02:48 -0700
committerDavid S. Miller <davem@davemloft.net>2017-07-01 16:15:14 -0700
commitd9925368a641391f38cd281e67b948e6b6f3bcca (patch)
tree8eb3087d8e67417dcc0892908fac9b1921e55b8b /samples
parent9872a4bde31b0b055448e9ac1f4c9ee62d978766 (diff)
download96b-common-d9925368a641391f38cd281e67b948e6b6f3bcca.tar.gz
bpf: Sample BPF program to set buffer sizes
This patch contains a BPF program to set initial receive window to 40 packets and send and receive buffers to 1.5MB. This would usually be done after doing appropriate checks that indicate the hosts are far enough away (i.e. large RTT). Signed-off-by: Lawrence Brakmo <brakmo@fb.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'samples')
-rw-r--r--samples/bpf/Makefile1
-rw-r--r--samples/bpf/tcp_bufs_kern.c86
2 files changed, 87 insertions, 0 deletions
diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
index ca955280cbeb..3b300db3d74d 100644
--- a/samples/bpf/Makefile
+++ b/samples/bpf/Makefile
@@ -115,6 +115,7 @@ always += test_map_in_map_kern.o
always += cookie_uid_helper_example.o
always += tcp_synrto_kern.o
always += tcp_rwnd_kern.o
+always += tcp_bufs_kern.o
HOSTCFLAGS += -I$(objtree)/usr/include
HOSTCFLAGS += -I$(srctree)/tools/lib/
diff --git a/samples/bpf/tcp_bufs_kern.c b/samples/bpf/tcp_bufs_kern.c
new file mode 100644
index 000000000000..ee83bbabd17c
--- /dev/null
+++ b/samples/bpf/tcp_bufs_kern.c
@@ -0,0 +1,86 @@
+/* Copyright (c) 2017 Facebook
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of version 2 of the GNU General Public
+ * License as published by the Free Software Foundation.
+ *
+ * BPF program to set initial receive window to 40 packets and send
+ * and receive buffers to 1.5MB. This would usually be done after
+ * doing appropriate checks that indicate the hosts are far enough
+ * away (i.e. large RTT).
+ *
+ * Use load_sock_ops to load this BPF program.
+ */
+
+#include <uapi/linux/bpf.h>
+#include <uapi/linux/if_ether.h>
+#include <uapi/linux/if_packet.h>
+#include <uapi/linux/ip.h>
+#include <linux/socket.h>
+#include "bpf_helpers.h"
+#include "bpf_endian.h"
+
+#define DEBUG 1
+
+#define bpf_printk(fmt, ...) \
+({ \
+ char ____fmt[] = fmt; \
+ bpf_trace_printk(____fmt, sizeof(____fmt), \
+ ##__VA_ARGS__); \
+})
+
+SEC("sockops")
+int bpf_bufs(struct bpf_sock_ops *skops)
+{
+ int bufsize = 1500000;
+ int rwnd_init = 40;
+ int rv = 0;
+ int op;
+
+ /* For testing purposes, only execute rest of BPF program
+ * if neither port numberis 55601
+ */
+ if (bpf_ntohl(skops->remote_port) != 55601 &&
+ skops->local_port != 55601)
+ return -1;
+
+ op = (int) skops->op;
+
+#ifdef DEBUG
+ bpf_printk("Returning %d\n", rv);
+#endif
+
+ /* Usually there would be a check to insure the hosts are far
+ * from each other so it makes sense to increase buffer sizes
+ */
+ switch (op) {
+ case BPF_SOCK_OPS_RWND_INIT:
+ rv = rwnd_init;
+ break;
+ case BPF_SOCK_OPS_TCP_CONNECT_CB:
+ /* Set sndbuf and rcvbuf of active connections */
+ rv = bpf_setsockopt(skops, SOL_SOCKET, SO_SNDBUF, &bufsize,
+ sizeof(bufsize));
+ rv = rv*100 + bpf_setsockopt(skops, SOL_SOCKET, SO_RCVBUF,
+ &bufsize, sizeof(bufsize));
+ break;
+ case BPF_SOCK_OPS_ACTIVE_ESTABLISHED_CB:
+ /* Nothing to do */
+ break;
+ case BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB:
+ /* Set sndbuf and rcvbuf of passive connections */
+ rv = bpf_setsockopt(skops, SOL_SOCKET, SO_SNDBUF, &bufsize,
+ sizeof(bufsize));
+ rv = rv*100 + bpf_setsockopt(skops, SOL_SOCKET, SO_RCVBUF,
+ &bufsize, sizeof(bufsize));
+ break;
+ default:
+ rv = -1;
+ }
+#ifdef DEBUG
+ bpf_printk("Returning %d\n", rv);
+#endif
+ skops->reply = rv;
+ return 1;
+}
+char _license[] SEC("license") = "GPL";