| Message ID | 20170628173124.3299500-5-brakmo@fb.com |
|---|---|
| State | Changes Requested, archived |
| Delegated to: | David Miller |
| Headers | show |
On Wed, 28 Jun 2017 10:31:12 -0700 Lawrence Brakmo <brakmo@fb.com> wrote: > +++ b/samples/bpf/tcp_synrto_kern.c > @@ -0,0 +1,60 @@ > +/* 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 SYN and SYN-ACK RTOs to 10ms when using IPv6 addresses > + * and the first 5.5 bytes of the IPv6 addresses are the same (in this example > + * that means both hosts are in the same datacenter. Missing end ")". I really like this short comment of what the program does, as it helps people browsing these sample programs. Can you also mention in the comment (of all these) bpf programs that people load this bpf object file via the program 'load_sock_ops'?
On 6/29/17, 12:39 PM, "netdev-owner@vger.kernel.org on behalf of Jesper Dangaard Brouer" <netdev-owner@vger.kernel.org on behalf of brouer@redhat.com> wrote:
On Wed, 28 Jun 2017 10:31:12 -0700
Lawrence Brakmo <brakmo@fb.com> wrote:
> +++ b/samples/bpf/tcp_synrto_kern.c
> @@ -0,0 +1,60 @@
> +/* 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 SYN and SYN-ACK RTOs to 10ms when using IPv6 addresses
> + * and the first 5.5 bytes of the IPv6 addresses are the same (in this example
> + * that means both hosts are in the same datacenter.
Missing end ")".
I really like this short comment of what the program does, as it helps
people browsing these sample programs.
Can you also mention in the comment (of all these) bpf programs that
people load this bpf object file via the program 'load_sock_ops'?
Thank you for finding the typo and for the comment on adding how to load the sample programs. Will be done in v5 due later today.
--
Best regards,
Jesper Dangaard Brouer
MSc.CS, Principal Kernel Engineer at Red Hat
LinkedIn: https://urldefense.proofpoint.com/v2/url?u=http-3A__www.linkedin.com_in_brouer&d=DwICAg&c=5VD0RTtNlTh3ycd41b3MUw&r=pq_Mqvzfy-C8ltkgyx1u_g&m=EJ1TyanCGEOIXEPnAm8BicVjUXEJLsvUQY1vNC_4r7g&s=INcdT-mimhOZEgFLw7hqg2V6VJ70XZJoeY83vp6V8YY&e=
diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile index 015589b..e29370a 100644 --- a/samples/bpf/Makefile +++ b/samples/bpf/Makefile @@ -113,6 +113,7 @@ always += lwt_len_hist_kern.o always += xdp_tx_iptunnel_kern.o always += test_map_in_map_kern.o always += cookie_uid_helper_example.o +always += tcp_synrto_kern.o HOSTCFLAGS += -I$(objtree)/usr/include HOSTCFLAGS += -I$(srctree)/tools/lib/ diff --git a/samples/bpf/tcp_synrto_kern.c b/samples/bpf/tcp_synrto_kern.c new file mode 100644 index 0000000..b16ac39 --- /dev/null +++ b/samples/bpf/tcp_synrto_kern.c @@ -0,0 +1,60 @@ +/* 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 SYN and SYN-ACK RTOs to 10ms when using IPv6 addresses + * and the first 5.5 bytes of the IPv6 addresses are the same (in this example + * that means both hosts are in the same datacenter. + */ + +#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" + +#define DEBUG 1 + +SEC("sockops") +int bpf_synrto(struct bpf_sock_ops *skops) +{ + char fmt1[] = "BPF command: %d\n"; + char fmt2[] = " Returning %d\n"; + int rv = -1; + int op; + + /* 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 + + /* Check for TIMEOUT_INIT operation and IPv6 addresses */ + if (op == BPF_SOCK_OPS_TIMEOUT_INIT && + skops->family == AF_INET6) { + + /* If the first 5.5 bytes of the IPv6 address are the same + * then both hosts are in the same datacenter + * so use an RTO of 10ms + */ + if (skops->local_ip6[0] == skops->remote_ip6[0] && + (skops->local_ip6[1] & 0xfff00000) == + (skops->remote_ip6[1] & 0xfff00000)) + rv = 10; + } +#ifdef DEBUG + bpf_trace_printk(fmt2, sizeof(fmt2), rv); +#endif + skops->reply = rv; + return 1; +} +char _license[] SEC("license") = "GPL";
The sample BPF program, tcp_synrto_kern.c, sets the SYN and SYN-ACK RTOs to 10ms when both hosts are within the same datacenter (i.e. small RTTs) in an environment where common IPv6 prefixes indicate both hosts are in the same data center. Signed-off-by: Lawrence Brakmo <brakmo@fb.com> --- samples/bpf/Makefile | 1 + samples/bpf/tcp_synrto_kern.c | 60 +++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 61 insertions(+) create mode 100644 samples/bpf/tcp_synrto_kern.c