From 0d25c43ab988766ad52ff2930af3bf47d92c20ac Mon Sep 17 00:00:00 2001 From: Jesper Dangaard Brouer Date: Mon, 25 Jun 2018 16:27:43 +0200 Subject: samples/bpf: extend xdp_rxq_info to read packet payload MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit There is a cost associated with reading the packet data payload that this test ignored. Add option --read to allow enabling reading part of the payload. This sample/tool helps us analyse an issue observed with a NIC mlx5 (ConnectX-5 Ex) and an Intel(R) Xeon(R) CPU E5-1650 v4. With no_touch of data: Running XDP on dev:mlx5p1 (ifindex:8) action:XDP_DROP options:no_touch XDP stats CPU pps issue-pps XDP-RX CPU 0 14,465,157 0 XDP-RX CPU 1 14,464,728 0 XDP-RX CPU 2 14,465,283 0 XDP-RX CPU 3 14,465,282 0 XDP-RX CPU 4 14,464,159 0 XDP-RX CPU 5 14,465,379 0 XDP-RX CPU total 86,789,992 When not touching data, we observe that the CPUs have idle cycles. When reading data the CPUs are 100% busy in softirq. With reading data: Running XDP on dev:mlx5p1 (ifindex:8) action:XDP_DROP options:read XDP stats CPU pps issue-pps XDP-RX CPU 0 9,620,639 0 XDP-RX CPU 1 9,489,843 0 XDP-RX CPU 2 9,407,854 0 XDP-RX CPU 3 9,422,289 0 XDP-RX CPU 4 9,321,959 0 XDP-RX CPU 5 9,395,242 0 XDP-RX CPU total 56,657,828 The effect seen above is a result of cache-misses occuring when more RXQs are being used. Based on perf-event observations, our conclusion is that the CPUs DDIO (Direct Data I/O) choose to deliver packet into main memory, instead of L3-cache. We also found, that this can be mitigated by either using less RXQs or by reducing NICs the RX-ring size. Signed-off-by: Jesper Dangaard Brouer Signed-off-by: Toke Høiland-Jørgensen Acked-by: Song Liu Signed-off-by: Daniel Borkmann --- samples/bpf/xdp_rxq_info_user.c | 34 ++++++++++++++++++++++++++++------ 1 file changed, 28 insertions(+), 6 deletions(-) (limited to 'samples/bpf/xdp_rxq_info_user.c') diff --git a/samples/bpf/xdp_rxq_info_user.c b/samples/bpf/xdp_rxq_info_user.c index e4e9ba52bff0..435485d4f49e 100644 --- a/samples/bpf/xdp_rxq_info_user.c +++ b/samples/bpf/xdp_rxq_info_user.c @@ -50,6 +50,7 @@ static const struct option long_options[] = { {"sec", required_argument, NULL, 's' }, {"no-separators", no_argument, NULL, 'z' }, {"action", required_argument, NULL, 'a' }, + {"readmem", no_argument, NULL, 'r' }, {0, 0, NULL, 0 } }; @@ -66,6 +67,11 @@ static void int_exit(int sig) struct config { __u32 action; int ifindex; + __u32 options; +}; +enum cfg_options_flags { + NO_TOUCH = 0x0U, + READ_MEM = 0x1U, }; #define XDP_ACTION_MAX (XDP_TX + 1) #define XDP_ACTION_MAX_STRLEN 11 @@ -109,6 +115,16 @@ static void list_xdp_actions(void) printf("\n"); } +static char* options2str(enum cfg_options_flags flag) +{ + if (flag == NO_TOUCH) + return "no_touch"; + if (flag & READ_MEM) + return "read"; + fprintf(stderr, "ERR: Unknown config option flags"); + exit(EXIT_FAIL); +} + static void usage(char *argv[]) { int i; @@ -305,7 +321,7 @@ static __u64 calc_errs_pps(struct datarec *r, static void stats_print(struct stats_record *stats_rec, struct stats_record *stats_prev, - int action) + int action, __u32 cfg_opt) { unsigned int nr_rxqs = bpf_map__def(rx_queue_index_map)->max_entries; unsigned int nr_cpus = bpf_num_possible_cpus(); @@ -316,8 +332,8 @@ static void stats_print(struct stats_record *stats_rec, int i; /* Header */ - printf("\nRunning XDP on dev:%s (ifindex:%d) action:%s\n", - ifname, ifindex, action2str(action)); + printf("\nRunning XDP on dev:%s (ifindex:%d) action:%s options:%s\n", + ifname, ifindex, action2str(action), options2str(cfg_opt)); /* stats_global_map */ { @@ -399,7 +415,7 @@ static inline void swap(struct stats_record **a, struct stats_record **b) *b = tmp; } -static void stats_poll(int interval, int action) +static void stats_poll(int interval, int action, __u32 cfg_opt) { struct stats_record *record, *prev; @@ -410,7 +426,7 @@ static void stats_poll(int interval, int action) while (1) { swap(&prev, &record); stats_collect(record); - stats_print(record, prev, action); + stats_print(record, prev, action, cfg_opt); sleep(interval); } @@ -421,6 +437,7 @@ static void stats_poll(int interval, int action) int main(int argc, char **argv) { + __u32 cfg_options= NO_TOUCH ; /* Default: Don't touch packet memory */ struct rlimit r = {10 * 1024 * 1024, RLIM_INFINITY}; struct bpf_prog_load_attr prog_load_attr = { .prog_type = BPF_PROG_TYPE_XDP, @@ -435,6 +452,7 @@ int main(int argc, char **argv) int interval = 2; __u32 key = 0; + char action_str_buf[XDP_ACTION_MAX_STRLEN + 1 /* for \0 */] = { 0 }; int action = XDP_PASS; /* Default action */ char *action_str = NULL; @@ -496,6 +514,9 @@ int main(int argc, char **argv) action_str = (char *)&action_str_buf; strncpy(action_str, optarg, XDP_ACTION_MAX_STRLEN); break; + case 'r': + cfg_options |= READ_MEM; + break; case 'h': error: default: @@ -522,6 +543,7 @@ int main(int argc, char **argv) } } cfg.action = action; + cfg.options = cfg_options; /* Trick to pretty printf with thousands separators use %' */ if (use_separators) @@ -542,6 +564,6 @@ int main(int argc, char **argv) return EXIT_FAIL_XDP; } - stats_poll(interval, action); + stats_poll(interval, action, cfg_options); return EXIT_OK; } -- cgit v1.2.3 From 509fda105ba8f9a1a5c6f8b79e4c7fc50b35c1e3 Mon Sep 17 00:00:00 2001 From: Jesper Dangaard Brouer Date: Mon, 25 Jun 2018 16:27:48 +0200 Subject: samples/bpf: xdp_rxq_info action XDP_TX must adjust MAC-addrs MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit XDP_TX requires also changing the MAC-addrs, else some hardware may drop the TX packet before reaching the wire. This was observed with driver mlx5. If xdp_rxq_info select --action XDP_TX the swapmac functionality is activated. It is also possible to manually enable via cmdline option --swapmac. This is practical if wanting to measure the overhead of writing/updating payload for other action types. Signed-off-by: Jesper Dangaard Brouer Signed-off-by: Toke Høiland-Jørgensen Acked-by: Song Liu Signed-off-by: Daniel Borkmann --- samples/bpf/xdp_rxq_info_kern.c | 26 +++++++++++++++++++++++++- samples/bpf/xdp_rxq_info_user.c | 11 +++++++++++ 2 files changed, 36 insertions(+), 1 deletion(-) (limited to 'samples/bpf/xdp_rxq_info_user.c') diff --git a/samples/bpf/xdp_rxq_info_kern.c b/samples/bpf/xdp_rxq_info_kern.c index 61af6210df2f..222a83eed1cb 100644 --- a/samples/bpf/xdp_rxq_info_kern.c +++ b/samples/bpf/xdp_rxq_info_kern.c @@ -21,6 +21,7 @@ struct config { enum cfg_options_flags { NO_TOUCH = 0x0U, READ_MEM = 0x1U, + SWAP_MAC = 0x2U, }; struct bpf_map_def SEC("maps") config_map = { .type = BPF_MAP_TYPE_ARRAY, @@ -52,6 +53,23 @@ struct bpf_map_def SEC("maps") rx_queue_index_map = { .max_entries = MAX_RXQs + 1, }; +static __always_inline +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]; +} + SEC("xdp_prog0") int xdp_prognum0(struct xdp_md *ctx) { @@ -98,7 +116,7 @@ int xdp_prognum0(struct xdp_md *ctx) rxq_rec->issue++; /* Default: Don't touch packet data, only count packets */ - if (unlikely(config->options & READ_MEM)) { + if (unlikely(config->options & (READ_MEM|SWAP_MAC))) { struct ethhdr *eth = data; if (eth + 1 > data_end) @@ -107,6 +125,12 @@ int xdp_prognum0(struct xdp_md *ctx) /* Avoid compiler removing this: Drop non 802.3 Ethertypes */ if (ntohs(eth->h_proto) < ETH_P_802_3_MIN) return XDP_ABORTED; + + /* XDP_TX requires changing MAC-addrs, else HW may drop. + * Can also be enabled with --swapmac (for test purposes) + */ + if (unlikely(config->options & SWAP_MAC)) + swap_src_dst_mac(data); } return config->action; diff --git a/samples/bpf/xdp_rxq_info_user.c b/samples/bpf/xdp_rxq_info_user.c index 435485d4f49e..248a7eab9531 100644 --- a/samples/bpf/xdp_rxq_info_user.c +++ b/samples/bpf/xdp_rxq_info_user.c @@ -51,6 +51,7 @@ static const struct option long_options[] = { {"no-separators", no_argument, NULL, 'z' }, {"action", required_argument, NULL, 'a' }, {"readmem", no_argument, NULL, 'r' }, + {"swapmac", no_argument, NULL, 'm' }, {0, 0, NULL, 0 } }; @@ -72,6 +73,7 @@ struct config { enum cfg_options_flags { NO_TOUCH = 0x0U, READ_MEM = 0x1U, + SWAP_MAC = 0x2U, }; #define XDP_ACTION_MAX (XDP_TX + 1) #define XDP_ACTION_MAX_STRLEN 11 @@ -119,6 +121,8 @@ static char* options2str(enum cfg_options_flags flag) { if (flag == NO_TOUCH) return "no_touch"; + if (flag & SWAP_MAC) + return "swapmac"; if (flag & READ_MEM) return "read"; fprintf(stderr, "ERR: Unknown config option flags"); @@ -517,6 +521,9 @@ int main(int argc, char **argv) case 'r': cfg_options |= READ_MEM; break; + case 'm': + cfg_options |= SWAP_MAC; + break; case 'h': error: default: @@ -543,6 +550,10 @@ int main(int argc, char **argv) } } cfg.action = action; + + /* XDP_TX requires changing MAC-addrs, else HW may drop */ + if (action == XDP_TX) + cfg_options |= SWAP_MAC; cfg.options = cfg_options; /* Trick to pretty printf with thousands separators use %' */ -- cgit v1.2.3