From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lawrence Brakmo Subject: [RFC PATCH net-next 13/15] bpf: Sample BPF program to set initial cwnd Date: Tue, 13 Jun 2017 11:00:02 -0700 Message-ID: <20170613180004.3008403-14-brakmo@fb.com> References: <20170613180004.3008403-1-brakmo@fb.com> Mime-Version: 1.0 Content-Type: text/plain Cc: Kernel Team , Blake Matheny , Alexei Starovoitov , Daniel Borkmann , David Ahern To: netdev Return-path: Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:52752 "EHLO mx0b-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753764AbdFMSAL (ORCPT ); Tue, 13 Jun 2017 14:00:11 -0400 Received: from pps.filterd (m0109332.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.0.20/8.16.0.20) with SMTP id v5DHwnqA027973 for ; Tue, 13 Jun 2017 11:00:10 -0700 Received: from mail.thefacebook.com ([199.201.64.23]) by mx0a-00082601.pphosted.com with ESMTP id 2b2j3jh313-3 (version=TLSv1 cipher=ECDHE-RSA-AES256-SHA bits=256 verify=NOT) for ; Tue, 13 Jun 2017 11:00:10 -0700 Received: from facebook.com (2401:db00:11:d025:face:0:13:0) by mx-out.facebook.com (10.102.107.97) with ESMTP id 237ce5de506211e79a800002c99331b0-78d3a8f0 for ; Tue, 13 Jun 2017 11:00:09 -0700 In-Reply-To: <20170613180004.3008403-1-brakmo@fb.com> Sender: netdev-owner@vger.kernel.org List-ID: Sample BPF program that assumes hosts are far away (i.e. large RTTs) and sets initial cwnd and initial receive window to 40 packets, send and receive buffers to 1.5MB. In practice there would be a test to insure the hosts are actually far enough away. Signed-off-by: Lawrence Brakmo --- samples/bpf/Makefile | 1 + samples/bpf/tcp_iw_kern.c | 73 +++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 74 insertions(+) create mode 100644 samples/bpf/tcp_iw_kern.c diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile index 1066c99..59ba879 100644 --- a/samples/bpf/Makefile +++ b/samples/bpf/Makefile @@ -117,6 +117,7 @@ always += tcp_synrto_kern.o always += tcp_rwnd_kern.o always += tcp_bufs_kern.o always += tcp_cong_kern.o +always += tcp_iw_kern.o HOSTCFLAGS += -I$(objtree)/usr/include HOSTCFLAGS += -I$(srctree)/tools/lib/ diff --git a/samples/bpf/tcp_iw_kern.c b/samples/bpf/tcp_iw_kern.c new file mode 100644 index 0000000..0279f7e --- /dev/null +++ b/samples/bpf/tcp_iw_kern.c @@ -0,0 +1,73 @@ +/* + * BPF program to set initial congestion window and 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). + */ + +#include +#include +#include +#include +#include +#include "bpf_helpers.h" + +#define DEBUG 1 + +SEC("sockops") +int bpf_iw(struct __sk_buff *skb) +{ + struct bpf_socket_ops *skops = (struct bpf_socket_ops *) skb; + char fmt1[] = "BPF command: %d\n"; + char fmt2[] = " Returning %d\n"; + int op; + int rv = 0; + int rwnd_init = 40; + int iw = 40; + int bufsize = 1500000; + + // For testing purposes, only execute rest of BPF program + // if neither port numberis 55601 + if (skops->remote_port != 55601 && skops->local_port != 55601) + return -1; + + op = (int) skops->op; + +#ifdef DEBUG + bpf_trace_printk(fmt1, sizeof(fmt1), op); +#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_SOCKET_OPS_RWND_INIT: + rv = rwnd_init; + break; + case BPF_SOCKET_OPS_TCP_CONNECT_CB: + // Set sndbuf and rcvbuf of active connections + rv = bpf_setsockopt(skb, SOL_SOCKET, SO_SNDBUF, &bufsize, + sizeof(bufsize)); + rv = -rv*100 + bpf_setsockopt(skb, SOL_SOCKET, SO_RCVBUF, + &bufsize, sizeof(bufsize)); + break; + case BPF_SOCKET_OPS_ACTIVE_ESTABLISHED_CB: + rv = bpf_setsockopt(skb, SOL_TCP, TCP_BPF_IW, &iw, + sizeof(iw)); + break; + case BPF_SOCKET_OPS_PASSIVE_ESTABLISHED_CB: + // Set sndbuf and rcvbuf of passive connections + rv = bpf_setsockopt(skb, SOL_SOCKET, SO_SNDBUF, &bufsize, + sizeof(bufsize)); + rv = -rv*100 + bpf_setsockopt(skb, SOL_SOCKET, SO_RCVBUF, + &bufsize, sizeof(bufsize)); + break; + default: + rv = -1; + } +#ifdef DEBUG + bpf_trace_printk(fmt2, sizeof(fmt2), rv); +#endif + return rv; +} +char _license[] SEC("license") = "GPL"; -- 2.9.3