From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alexei Starovoitov Subject: Re: [PATCH v10 12/12] bpf: add sample for xdp forwarding and rewrite Date: Wed, 3 Aug 2016 10:11:20 -0700 Message-ID: <20160803171118.GA37742@ast-mbp.thefacebook.com> References: <1468955817-10604-1-git-send-email-bblanco@plumgrid.com> <1468955817-10604-13-git-send-email-bblanco@plumgrid.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Brenden Blanco , "David S. Miller" , Linux Kernel Network Developers , Jamal Hadi Salim , Saeed Mahameed , Martin KaFai Lau , Jesper Dangaard Brouer , Ari Saha , Or Gerlitz , john fastabend , Hannes Frederic Sowa , Thomas Graf , Daniel Borkmann , Tariq Toukan , Aaron Yue To: Tom Herbert Return-path: Received: from mail-pf0-f195.google.com ([209.85.192.195]:36668 "EHLO mail-pf0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932475AbcHCRMr (ORCPT ); Wed, 3 Aug 2016 13:12:47 -0400 Received: by mail-pf0-f195.google.com with SMTP id y134so14975901pfg.3 for ; Wed, 03 Aug 2016 10:11:25 -0700 (PDT) Content-Disposition: inline In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: On Wed, Aug 03, 2016 at 10:01:54AM -0700, Tom Herbert wrote: > On Tue, Jul 19, 2016 at 12:16 PM, Brenden Blanco wrote: > > Add a sample that rewrites and forwards packets out on the same > > interface. Observed single core forwarding performance of ~10Mpps. > > > > Since the mlx4 driver under test recycles every single packet page, the > > perf output shows almost exclusively just the ring management and bpf > > program work. Slowdowns are likely occurring due to cache misses. > > > > Signed-off-by: Brenden Blanco > > --- > > samples/bpf/Makefile | 5 +++ > > samples/bpf/xdp2_kern.c | 114 ++++++++++++++++++++++++++++++++++++++++++++++++ > > 2 files changed, 119 insertions(+) > > create mode 100644 samples/bpf/xdp2_kern.c > > > > diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile > > index 0e4ab3a..d2d2b35 100644 > > --- a/samples/bpf/Makefile > > +++ b/samples/bpf/Makefile > > @@ -22,6 +22,7 @@ hostprogs-y += map_perf_test > > hostprogs-y += test_overhead > > hostprogs-y += test_cgrp2_array_pin > > hostprogs-y += xdp1 > > +hostprogs-y += xdp2 > > > > test_verifier-objs := test_verifier.o libbpf.o > > test_maps-objs := test_maps.o libbpf.o > > @@ -44,6 +45,8 @@ map_perf_test-objs := bpf_load.o libbpf.o map_perf_test_user.o > > test_overhead-objs := bpf_load.o libbpf.o test_overhead_user.o > > test_cgrp2_array_pin-objs := libbpf.o test_cgrp2_array_pin.o > > xdp1-objs := bpf_load.o libbpf.o xdp1_user.o > > +# reuse xdp1 source intentionally > > +xdp2-objs := bpf_load.o libbpf.o xdp1_user.o > > > > # Tell kbuild to always build the programs > > always := $(hostprogs-y) > > @@ -67,6 +70,7 @@ always += test_overhead_kprobe_kern.o > > always += parse_varlen.o parse_simple.o parse_ldabs.o > > always += test_cgrp2_tc_kern.o > > always += xdp1_kern.o > > +always += xdp2_kern.o > > > > HOSTCFLAGS += -I$(objtree)/usr/include > > > > @@ -88,6 +92,7 @@ HOSTLOADLIBES_spintest += -lelf > > HOSTLOADLIBES_map_perf_test += -lelf -lrt > > HOSTLOADLIBES_test_overhead += -lelf -lrt > > HOSTLOADLIBES_xdp1 += -lelf > > +HOSTLOADLIBES_xdp2 += -lelf > > > > # Allows pointing LLC/CLANG to a LLVM backend with bpf support, redefine on cmdline: > > # make samples/bpf/ LLC=~/git/llvm/build/bin/llc CLANG=~/git/llvm/build/bin/clang > > diff --git a/samples/bpf/xdp2_kern.c b/samples/bpf/xdp2_kern.c > > new file mode 100644 > > index 0000000..38fe7e1 > > --- /dev/null > > +++ b/samples/bpf/xdp2_kern.c > > @@ -0,0 +1,114 @@ > > +/* Copyright (c) 2016 PLUMgrid > > + * > > + * 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. > > + */ > > +#define KBUILD_MODNAME "foo" > > +#include > > +#include > > +#include > > +#include > > +#include > > +#include > > +#include > > +#include "bpf_helpers.h" > > + > > +struct bpf_map_def SEC("maps") dropcnt = { > > + .type = BPF_MAP_TYPE_PERCPU_ARRAY, > > + .key_size = sizeof(u32), > > + .value_size = sizeof(long), > > + .max_entries = 256, > > +}; > > + > > +static void swap_src_dst_mac(void *data) > > +{ > > + unsigned short *p = data; > > + unsigned short dst[3]; > > + > > + dst[0] = p[0]; > > + dst[1] = p[1]; > > + dst[2] = p[2]; > > + p[0] = p[3]; > > + p[1] = p[4]; > > + p[2] = p[5]; > > + p[3] = dst[0]; > > + p[4] = dst[1]; > > + p[5] = dst[2]; > > +} > > + > > +static int parse_ipv4(void *data, u64 nh_off, void *data_end) > > +{ > > + struct iphdr *iph = data + nh_off; > > + > > + if (iph + 1 > data_end) > > + return 0; > > + return iph->protocol; > > +} > > + > > +static int parse_ipv6(void *data, u64 nh_off, void *data_end) > > +{ > > + struct ipv6hdr *ip6h = data + nh_off; > > + > > + if (ip6h + 1 > data_end) > > + return 0; > > + return ip6h->nexthdr; > > +} > > + > > +SEC("xdp1") > > +int xdp_prog1(struct xdp_md *ctx) > > +{ > > + void *data_end = (void *)(long)ctx->data_end; > > + void *data = (void *)(long)ctx->data; > > Brendan, > > It seems that the cast to long here is done because data_end and data > are u32s in xdp_md. So the effect is that we are upcasting a > thirty-bit integer into a sixty-four bit pointer (in fact without the > cast we see compiler warnings). I don't understand how this can be > correct. Can you shed some light on this? please see: http://lists.iovisor.org/pipermail/iovisor-dev/2016-August/000355.html