linux/samples/bpf/hbm.c
brakmo 71634d7f92 bpf: Add support for fq's EDT to HBM
Adds support for fq's Earliest Departure Time to HBM (Host Bandwidth
Manager). Includes a new BPF program supporting EDT, and also updates
corresponding programs.

It will drop packets with an EDT of more than 500us in the future
unless the packet belongs to a flow with less than 2 packets in flight.
This is done so each flow has at least 2 packets in flight, so they
will not starve, and also to help prevent delayed ACK timeouts.

It will also work with ECN enabled traffic, where the packets will be
CE marked if their EDT is more than 50us in the future.

The table below shows some performance numbers. The flows are back to
back RPCS. One server sending to another, either 2 or 4 flows.
One flow is a 10KB RPC, the rest are 1MB RPCs. When there are more
than one flow of a given RPC size, the numbers represent averages.

The rate limit applies to all flows (they are in the same cgroup).
Tests ending with "-edt" ran with the new BPF program supporting EDT.
Tests ending with "-hbt" ran on top HBT qdisc with the specified rate
(i.e. no HBM). The other tests ran with the HBM BPF program included
in the HBM patch-set.

EDT has limited value when using DCTCP, but it helps in many cases when
using Cubic. It usually achieves larger link utilization and lower
99% latencies for the 1MB RPCs.
HBM ends up queueing a lot of packets with its default parameter values,
reducing the goodput of the 10KB RPCs and increasing their latency. Also,
the RTTs seen by the flows are quite large.

                         Aggr              10K  10K  10K   1MB  1MB  1MB
         Limit           rate drops  RTT  rate  P90  P99  rate  P90  P99
Test      rate  Flows    Mbps   %     us  Mbps   us   us  Mbps   ms   ms
--------  ----  -----    ---- -----  ---  ---- ---- ----  ---- ---- ----
cubic       1G    2       904  0.02  108   257  511  539   647 13.4 24.5
cubic-edt   1G    2       982  0.01  156   239  656  967   743 14.0 17.2
dctcp       1G    2       977  0.00  105   324  408  744   653 14.5 15.9
dctcp-edt   1G    2       981  0.01  142   321  417  811   660 15.7 17.0
cubic-htb   1G    2       919  0.00 1825    40 2822 4140   879  9.7  9.9

cubic     200M    2       155  0.30  220    81  532  655    74  283  450
cubic-edt 200M    2       188  0.02  222    87 1035 1095   101   84   85
dctcp     200M    2       188  0.03  111    77  912  939   111   76  325
dctcp-edt 200M    2       188  0.03  217    74 1416 1738   114   76   79
cubic-htb 200M    2       188  0.00 5015     8 14ms 15ms   180   48   50

cubic       1G    4       952  0.03  110   165  516  546   262   38  154
cubic-edt   1G    4       973  0.01  190   111 1034 1314   287   65   79
dctcp       1G    4       951  0.00  103   180  617  905   257   37   38
dctcp-edt   1G    4       967  0.00  163   151  732 1126   272   43   55
cubic-htb   1G    4       914  0.00 3249    13  7ms  8ms   300   29   34

cubic       5G    4      4236  0.00  134   305  490  624  1310   10   17
cubic-edt   5G    4      4865  0.00  156   306  425  759  1520   10   16
dctcp       5G    4      4936  0.00  128   485  221  409  1484    7    9
dctcp-edt   5G    4      4924  0.00  148   390  392  623  1508   11   26

v1 -> v2: Incorporated Andrii's suggestions
v2 -> v3: Incorporated Yonghong's suggestions
v3 -> v4: Removed credit update that is not needed

Signed-off-by: Lawrence Brakmo <brakmo@fb.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
2019-07-03 15:03:00 +02:00

499 lines
13 KiB
C

// SPDX-License-Identifier: GPL-2.0
/* Copyright (c) 2019 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.
*
* Example program for Host Bandwidth Managment
*
* This program loads a cgroup skb BPF program to enforce cgroup output
* (egress) or input (ingress) bandwidth limits.
*
* USAGE: hbm [-d] [-l] [-n <id>] [-r <rate>] [-s] [-t <secs>] [-w] [-h] [prog]
* Where:
* -d Print BPF trace debug buffer
* -l Also limit flows doing loopback
* -n <#> To create cgroup \"/hbm#\" and attach prog
* Default is /hbm1
* --no_cn Do not return cn notifications
* -r <rate> Rate limit in Mbps
* -s Get HBM stats (marked, dropped, etc.)
* -t <time> Exit after specified seconds (default is 0)
* -w Work conserving flag. cgroup can increase its bandwidth
* beyond the rate limit specified while there is available
* bandwidth. Current implementation assumes there is only
* NIC (eth0), but can be extended to support multiple NICs.
* Currrently only supported for egress.
* -h Print this info
* prog BPF program file name. Name defaults to hbm_out_kern.o
*/
#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include <sys/resource.h>
#include <sys/time.h>
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#include <linux/unistd.h>
#include <linux/bpf.h>
#include <bpf/bpf.h>
#include <getopt.h>
#include "bpf_load.h"
#include "bpf_rlimit.h"
#include "cgroup_helpers.h"
#include "hbm.h"
#include "bpf_util.h"
#include "bpf.h"
#include "libbpf.h"
bool outFlag = true;
int minRate = 1000; /* cgroup rate limit in Mbps */
int rate = 1000; /* can grow if rate conserving is enabled */
int dur = 1;
bool stats_flag;
bool loopback_flag;
bool debugFlag;
bool work_conserving_flag;
bool no_cn_flag;
bool edt_flag;
static void Usage(void);
static void read_trace_pipe2(void);
static void do_error(char *msg, bool errno_flag);
#define DEBUGFS "/sys/kernel/debug/tracing/"
struct bpf_object *obj;
int bpfprog_fd;
int cgroup_storage_fd;
static void read_trace_pipe2(void)
{
int trace_fd;
FILE *outf;
char *outFname = "hbm_out.log";
trace_fd = open(DEBUGFS "trace_pipe", O_RDONLY, 0);
if (trace_fd < 0) {
printf("Error opening trace_pipe\n");
return;
}
// Future support of ingress
// if (!outFlag)
// outFname = "hbm_in.log";
outf = fopen(outFname, "w");
if (outf == NULL)
printf("Error creating %s\n", outFname);
while (1) {
static char buf[4097];
ssize_t sz;
sz = read(trace_fd, buf, sizeof(buf) - 1);
if (sz > 0) {
buf[sz] = 0;
puts(buf);
if (outf != NULL) {
fprintf(outf, "%s\n", buf);
fflush(outf);
}
}
}
}
static void do_error(char *msg, bool errno_flag)
{
if (errno_flag)
printf("ERROR: %s, errno: %d\n", msg, errno);
else
printf("ERROR: %s\n", msg);
exit(1);
}
static int prog_load(char *prog)
{
struct bpf_prog_load_attr prog_load_attr = {
.prog_type = BPF_PROG_TYPE_CGROUP_SKB,
.file = prog,
.expected_attach_type = BPF_CGROUP_INET_EGRESS,
};
int map_fd;
struct bpf_map *map;
int ret = 0;
if (access(prog, O_RDONLY) < 0) {
printf("Error accessing file %s: %s\n", prog, strerror(errno));
return 1;
}
if (bpf_prog_load_xattr(&prog_load_attr, &obj, &bpfprog_fd))
ret = 1;
if (!ret) {
map = bpf_object__find_map_by_name(obj, "queue_stats");
map_fd = bpf_map__fd(map);
if (map_fd < 0) {
printf("Map not found: %s\n", strerror(map_fd));
ret = 1;
}
}
if (ret) {
printf("ERROR: load_bpf_file failed for: %s\n", prog);
printf(" Output from verifier:\n%s\n------\n", bpf_log_buf);
ret = -1;
} else {
ret = map_fd;
}
return ret;
}
static int run_bpf_prog(char *prog, int cg_id)
{
int map_fd;
int rc = 0;
int key = 0;
int cg1 = 0;
int type = BPF_CGROUP_INET_EGRESS;
char cg_dir[100];
struct hbm_queue_stats qstats = {0};
sprintf(cg_dir, "/hbm%d", cg_id);
map_fd = prog_load(prog);
if (map_fd == -1)
return 1;
if (setup_cgroup_environment()) {
printf("ERROR: setting cgroup environment\n");
goto err;
}
cg1 = create_and_get_cgroup(cg_dir);
if (!cg1) {
printf("ERROR: create_and_get_cgroup\n");
goto err;
}
if (join_cgroup(cg_dir)) {
printf("ERROR: join_cgroup\n");
goto err;
}
qstats.rate = rate;
qstats.stats = stats_flag ? 1 : 0;
qstats.loopback = loopback_flag ? 1 : 0;
qstats.no_cn = no_cn_flag ? 1 : 0;
if (bpf_map_update_elem(map_fd, &key, &qstats, BPF_ANY)) {
printf("ERROR: Could not update map element\n");
goto err;
}
if (!outFlag)
type = BPF_CGROUP_INET_INGRESS;
if (bpf_prog_attach(bpfprog_fd, cg1, type, 0)) {
printf("ERROR: bpf_prog_attach fails!\n");
log_err("Attaching prog");
goto err;
}
if (work_conserving_flag) {
struct timeval t0, t_last, t_new;
FILE *fin;
unsigned long long last_eth_tx_bytes, new_eth_tx_bytes;
signed long long last_cg_tx_bytes, new_cg_tx_bytes;
signed long long delta_time, delta_bytes, delta_rate;
int delta_ms;
#define DELTA_RATE_CHECK 10000 /* in us */
#define RATE_THRESHOLD 9500000000 /* 9.5 Gbps */
bpf_map_lookup_elem(map_fd, &key, &qstats);
if (gettimeofday(&t0, NULL) < 0)
do_error("gettimeofday failed", true);
t_last = t0;
fin = fopen("/sys/class/net/eth0/statistics/tx_bytes", "r");
if (fscanf(fin, "%llu", &last_eth_tx_bytes) != 1)
do_error("fscanf fails", false);
fclose(fin);
last_cg_tx_bytes = qstats.bytes_total;
while (true) {
usleep(DELTA_RATE_CHECK);
if (gettimeofday(&t_new, NULL) < 0)
do_error("gettimeofday failed", true);
delta_ms = (t_new.tv_sec - t0.tv_sec) * 1000 +
(t_new.tv_usec - t0.tv_usec)/1000;
if (delta_ms > dur * 1000)
break;
delta_time = (t_new.tv_sec - t_last.tv_sec) * 1000000 +
(t_new.tv_usec - t_last.tv_usec);
if (delta_time == 0)
continue;
t_last = t_new;
fin = fopen("/sys/class/net/eth0/statistics/tx_bytes",
"r");
if (fscanf(fin, "%llu", &new_eth_tx_bytes) != 1)
do_error("fscanf fails", false);
fclose(fin);
printf(" new_eth_tx_bytes:%llu\n",
new_eth_tx_bytes);
bpf_map_lookup_elem(map_fd, &key, &qstats);
new_cg_tx_bytes = qstats.bytes_total;
delta_bytes = new_eth_tx_bytes - last_eth_tx_bytes;
last_eth_tx_bytes = new_eth_tx_bytes;
delta_rate = (delta_bytes * 8000000) / delta_time;
printf("%5d - eth_rate:%.1fGbps cg_rate:%.3fGbps",
delta_ms, delta_rate/1000000000.0,
rate/1000.0);
if (delta_rate < RATE_THRESHOLD) {
/* can increase cgroup rate limit, but first
* check if we are using the current limit.
* Currently increasing by 6.25%, unknown
* if that is the optimal rate.
*/
int rate_diff100;
delta_bytes = new_cg_tx_bytes -
last_cg_tx_bytes;
last_cg_tx_bytes = new_cg_tx_bytes;
delta_rate = (delta_bytes * 8000000) /
delta_time;
printf(" rate:%.3fGbps",
delta_rate/1000000000.0);
rate_diff100 = (((long long)rate)*1000000 -
delta_rate) * 100 /
(((long long) rate) * 1000000);
printf(" rdiff:%d", rate_diff100);
if (rate_diff100 <= 3) {
rate += (rate >> 4);
if (rate > RATE_THRESHOLD / 1000000)
rate = RATE_THRESHOLD / 1000000;
qstats.rate = rate;
printf(" INC\n");
} else {
printf("\n");
}
} else {
/* Need to decrease cgroup rate limit.
* Currently decreasing by 12.5%, unknown
* if that is optimal
*/
printf(" DEC\n");
rate -= (rate >> 3);
if (rate < minRate)
rate = minRate;
qstats.rate = rate;
}
if (bpf_map_update_elem(map_fd, &key, &qstats, BPF_ANY))
do_error("update map element fails", false);
}
} else {
sleep(dur);
}
// Get stats!
if (stats_flag && bpf_map_lookup_elem(map_fd, &key, &qstats)) {
char fname[100];
FILE *fout;
if (!outFlag)
sprintf(fname, "hbm.%d.in", cg_id);
else
sprintf(fname, "hbm.%d.out", cg_id);
fout = fopen(fname, "w");
fprintf(fout, "id:%d\n", cg_id);
fprintf(fout, "ERROR: Could not lookup queue_stats\n");
} else if (stats_flag && qstats.lastPacketTime >
qstats.firstPacketTime) {
long long delta_us = (qstats.lastPacketTime -
qstats.firstPacketTime)/1000;
unsigned int rate_mbps = ((qstats.bytes_total -
qstats.bytes_dropped) * 8 /
delta_us);
double percent_pkts, percent_bytes;
char fname[100];
FILE *fout;
int k;
static const char *returnValNames[] = {
"DROP_PKT",
"ALLOW_PKT",
"DROP_PKT_CWR",
"ALLOW_PKT_CWR"
};
#define RET_VAL_COUNT 4
// Future support of ingress
// if (!outFlag)
// sprintf(fname, "hbm.%d.in", cg_id);
// else
sprintf(fname, "hbm.%d.out", cg_id);
fout = fopen(fname, "w");
fprintf(fout, "id:%d\n", cg_id);
fprintf(fout, "rate_mbps:%d\n", rate_mbps);
fprintf(fout, "duration:%.1f secs\n",
(qstats.lastPacketTime - qstats.firstPacketTime) /
1000000000.0);
fprintf(fout, "packets:%d\n", (int)qstats.pkts_total);
fprintf(fout, "bytes_MB:%d\n", (int)(qstats.bytes_total /
1000000));
fprintf(fout, "pkts_dropped:%d\n", (int)qstats.pkts_dropped);
fprintf(fout, "bytes_dropped_MB:%d\n",
(int)(qstats.bytes_dropped /
1000000));
// Marked Pkts and Bytes
percent_pkts = (qstats.pkts_marked * 100.0) /
(qstats.pkts_total + 1);
percent_bytes = (qstats.bytes_marked * 100.0) /
(qstats.bytes_total + 1);
fprintf(fout, "pkts_marked_percent:%6.2f\n", percent_pkts);
fprintf(fout, "bytes_marked_percent:%6.2f\n", percent_bytes);
// Dropped Pkts and Bytes
percent_pkts = (qstats.pkts_dropped * 100.0) /
(qstats.pkts_total + 1);
percent_bytes = (qstats.bytes_dropped * 100.0) /
(qstats.bytes_total + 1);
fprintf(fout, "pkts_dropped_percent:%6.2f\n", percent_pkts);
fprintf(fout, "bytes_dropped_percent:%6.2f\n", percent_bytes);
// ECN CE markings
percent_pkts = (qstats.pkts_ecn_ce * 100.0) /
(qstats.pkts_total + 1);
fprintf(fout, "pkts_ecn_ce:%6.2f (%d)\n", percent_pkts,
(int)qstats.pkts_ecn_ce);
// Average cwnd
fprintf(fout, "avg cwnd:%d\n",
(int)(qstats.sum_cwnd / (qstats.sum_cwnd_cnt + 1)));
// Average rtt
fprintf(fout, "avg rtt:%d\n",
(int)(qstats.sum_rtt / (qstats.pkts_total + 1)));
// Average credit
if (edt_flag)
fprintf(fout, "avg credit_ms:%.03f\n",
(qstats.sum_credit /
(qstats.pkts_total + 1.0)) / 1000000.0);
else
fprintf(fout, "avg credit:%d\n",
(int)(qstats.sum_credit /
(1500 * ((int)qstats.pkts_total ) + 1)));
// Return values stats
for (k = 0; k < RET_VAL_COUNT; k++) {
percent_pkts = (qstats.returnValCount[k] * 100.0) /
(qstats.pkts_total + 1);
fprintf(fout, "%s:%6.2f (%d)\n", returnValNames[k],
percent_pkts, (int)qstats.returnValCount[k]);
}
fclose(fout);
}
if (debugFlag)
read_trace_pipe2();
return rc;
err:
rc = 1;
if (cg1)
close(cg1);
cleanup_cgroup_environment();
return rc;
}
static void Usage(void)
{
printf("This program loads a cgroup skb BPF program to enforce\n"
"cgroup output (egress) bandwidth limits.\n\n"
"USAGE: hbm [-o] [-d] [-l] [-n <id>] [--no_cn] [-r <rate>]\n"
" [-s] [-t <secs>] [-w] [-h] [prog]\n"
" Where:\n"
" -o indicates egress direction (default)\n"
" -d print BPF trace debug buffer\n"
" --edt use fq's Earliest Departure Time\n"
" -l also limit flows using loopback\n"
" -n <#> to create cgroup \"/hbm#\" and attach prog\n"
" Default is /hbm1\n"
" --no_cn disable CN notifications\n"
" -r <rate> Rate in Mbps\n"
" -s Update HBM stats\n"
" -t <time> Exit after specified seconds (default is 0)\n"
" -w Work conserving flag. cgroup can increase\n"
" bandwidth beyond the rate limit specified\n"
" while there is available bandwidth. Current\n"
" implementation assumes there is only eth0\n"
" but can be extended to support multiple NICs\n"
" -h print this info\n"
" prog BPF program file name. Name defaults to\n"
" hbm_out_kern.o\n");
}
int main(int argc, char **argv)
{
char *prog = "hbm_out_kern.o";
int k;
int cg_id = 1;
char *optstring = "iodln:r:st:wh";
struct option loptions[] = {
{"no_cn", 0, NULL, 1},
{"edt", 0, NULL, 2},
{NULL, 0, NULL, 0}
};
while ((k = getopt_long(argc, argv, optstring, loptions, NULL)) != -1) {
switch (k) {
case 1:
no_cn_flag = true;
break;
case 2:
prog = "hbm_edt_kern.o";
edt_flag = true;
break;
case'o':
break;
case 'd':
debugFlag = true;
break;
case 'l':
loopback_flag = true;
break;
case 'n':
cg_id = atoi(optarg);
break;
case 'r':
minRate = atoi(optarg) * 1.024;
rate = minRate;
break;
case 's':
stats_flag = true;
break;
case 't':
dur = atoi(optarg);
break;
case 'w':
work_conserving_flag = true;
break;
case '?':
if (optopt == 'n' || optopt == 'r' || optopt == 't')
fprintf(stderr,
"Option -%c requires an argument.\n\n",
optopt);
case 'h':
// fallthrough
default:
Usage();
return 0;
}
}
if (optind < argc)
prog = argv[optind];
printf("HBM prog: %s\n", prog != NULL ? prog : "NULL");
return run_bpf_prog(prog, cg_id);
}