* [iproute2 1/2] tc: Add support for the CBS qdisc
2017-10-26 17:17 [iproute2 0/2][pull request] Intel Wired LAN Driver Updates 2017-10-26 Jeff Kirsher
@ 2017-10-26 17:17 ` Jeff Kirsher
2017-11-01 21:24 ` Stephen Hemminger
2017-10-26 17:17 ` [iproute2 2/2] man: Add initial manpage for tc-cbs(8) Jeff Kirsher
1 sibling, 1 reply; 4+ messages in thread
From: Jeff Kirsher @ 2017-10-26 17:17 UTC (permalink / raw)
To: davem
Cc: Vinicius Costa Gomes, netdev, nhorman, sassmann, jogreene, Jeff Kirsher
From: Vinicius Costa Gomes <vinicius.gomes@intel.com>
The Credit Based Shaper (CBS) queueing discipline allows bandwidth
reservation with sub-milisecond precision. It is defined by the
802.1Q-2014 specification (section 8.6.8.2 and Annex L).
The syntax is:
tc qdisc add dev DEV parent NODE cbs locredit <LOCREDIT>
hicredit <HICREDIT> sendslope <SENDSLOPE>
idleslope <IDLESLOPE>
(The order is not important)
Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
---
tc/Makefile | 1 +
tc/q_cbs.c | 142 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 143 insertions(+)
create mode 100644 tc/q_cbs.c
diff --git a/tc/Makefile b/tc/Makefile
index 777de5e6..24bd3e2e 100644
--- a/tc/Makefile
+++ b/tc/Makefile
@@ -69,6 +69,7 @@ TCMODULES += q_hhf.o
TCMODULES += q_clsact.o
TCMODULES += e_bpf.o
TCMODULES += f_matchall.o
+TCMODULES += q_cbs.o
TCSO :=
ifeq ($(TC_CONFIG_ATM),y)
diff --git a/tc/q_cbs.c b/tc/q_cbs.c
new file mode 100644
index 00000000..e53be654
--- /dev/null
+++ b/tc/q_cbs.c
@@ -0,0 +1,142 @@
+/*
+ * q_cbs.c CBS.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ *
+ * Authors: Vinicius Costa Gomes <vinicius.gomes@intel.com>
+ *
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <syslog.h>
+#include <fcntl.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+#include <string.h>
+
+#include "utils.h"
+#include "tc_util.h"
+
+static void explain(void)
+{
+ fprintf(stderr, "Usage: ... cbs hicredit BYTES locredit BYTES sendslope BPS idleslope BPS\n");
+ fprintf(stderr, " [offload 0|1]\n");
+
+}
+
+static void explain1(const char *arg, const char *val)
+{
+ fprintf(stderr, "cbs: illegal value for \"%s\": \"%s\"\n", arg, val);
+}
+
+static int cbs_parse_opt(struct qdisc_util *qu, int argc, char **argv, struct nlmsghdr *n)
+{
+ struct tc_cbs_qopt opt = {};
+ struct rtattr *tail;
+
+ while (argc > 0) {
+ if (matches(*argv, "offload") == 0) {
+ NEXT_ARG();
+ if (opt.offload) {
+ fprintf(stderr, "cbs: duplicate \"offload\" specification\n");
+ return -1;
+ }
+ if (get_u8(&opt.offload, *argv, 0)) {
+ explain1("offload", *argv);
+ return -1;
+ }
+ } else if (matches(*argv, "hicredit") == 0) {
+ NEXT_ARG();
+ if (opt.hicredit) {
+ fprintf(stderr, "cbs: duplicate \"hicredit\" specification\n");
+ return -1;
+ }
+ if (get_s32(&opt.hicredit, *argv, 0)) {
+ explain1("hicredit", *argv);
+ return -1;
+ }
+ } else if (matches(*argv, "locredit") == 0) {
+ NEXT_ARG();
+ if (opt.locredit) {
+ fprintf(stderr, "cbs: duplicate \"locredit\" specification\n");
+ return -1;
+ }
+ if (get_s32(&opt.locredit, *argv, 0)) {
+ explain1("locredit", *argv);
+ return -1;
+ }
+ } else if (matches(*argv, "sendslope") == 0) {
+ NEXT_ARG();
+ if (opt.sendslope) {
+ fprintf(stderr, "cbs: duplicate \"sendslope\" specification\n");
+ return -1;
+ }
+ if (get_s32(&opt.sendslope, *argv, 0)) {
+ explain1("sendslope", *argv);
+ return -1;
+ }
+ } else if (matches(*argv, "idleslope") == 0) {
+ NEXT_ARG();
+ if (opt.idleslope) {
+ fprintf(stderr, "cbs: duplicate \"idleslope\" specification\n");
+ return -1;
+ }
+ if (get_s32(&opt.idleslope, *argv, 0)) {
+ explain1("idleslope", *argv);
+ return -1;
+ }
+ } else if (strcmp(*argv, "help") == 0) {
+ explain();
+ return -1;
+ } else {
+ fprintf(stderr, "cbs: unknown parameter \"%s\"\n", *argv);
+ explain();
+ return -1;
+ }
+ argc--; argv++;
+ }
+
+ tail = NLMSG_TAIL(n);
+ addattr_l(n, 1024, TCA_OPTIONS, NULL, 0);
+ addattr_l(n, 2024, TCA_CBS_PARMS, &opt, sizeof(opt));
+ tail->rta_len = (void *) NLMSG_TAIL(n) - (void *) tail;
+ return 0;
+}
+
+static int cbs_print_opt(struct qdisc_util *qu, FILE *f, struct rtattr *opt)
+{
+ struct rtattr *tb[TCA_CBS_MAX+1];
+ struct tc_cbs_qopt *qopt;
+
+ if (opt == NULL)
+ return 0;
+
+ parse_rtattr_nested(tb, TCA_CBS_MAX, opt);
+
+ if (tb[TCA_CBS_PARMS] == NULL)
+ return -1;
+
+ qopt = RTA_DATA(tb[TCA_CBS_PARMS]);
+ if (RTA_PAYLOAD(tb[TCA_CBS_PARMS]) < sizeof(*qopt))
+ return -1;
+
+ fprintf(f, "hicredit %d ", qopt->hicredit);
+ fprintf(f, "locredit %d ", qopt->locredit);
+ fprintf(f, "sendslope %d ", qopt->sendslope);
+ fprintf(f, "idleslope %d ", qopt->idleslope);
+ fprintf(f, "offload %d ", qopt->offload);
+
+ return 0;
+}
+
+struct qdisc_util cbs_qdisc_util = {
+ .id = "cbs",
+ .parse_qopt = cbs_parse_opt,
+ .print_qopt = cbs_print_opt,
+};
--
2.14.2
^ permalink raw reply related [flat|nested] 4+ messages in thread* [iproute2 2/2] man: Add initial manpage for tc-cbs(8)
2017-10-26 17:17 [iproute2 0/2][pull request] Intel Wired LAN Driver Updates 2017-10-26 Jeff Kirsher
2017-10-26 17:17 ` [iproute2 1/2] tc: Add support for the CBS qdisc Jeff Kirsher
@ 2017-10-26 17:17 ` Jeff Kirsher
1 sibling, 0 replies; 4+ messages in thread
From: Jeff Kirsher @ 2017-10-26 17:17 UTC (permalink / raw)
To: davem
Cc: Vinicius Costa Gomes, netdev, nhorman, sassmann, jogreene, Jeff Kirsher
From: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
---
man/man8/tc-cbs.8 | 112 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 112 insertions(+)
create mode 100644 man/man8/tc-cbs.8
diff --git a/man/man8/tc-cbs.8 b/man/man8/tc-cbs.8
new file mode 100644
index 00000000..97e00c84
--- /dev/null
+++ b/man/man8/tc-cbs.8
@@ -0,0 +1,112 @@
+.TH CBS 8 "18 Sept 2017" "iproute2" "Linux"
+.SH NAME
+CBS \- Credit Based Shaper (CBS) Qdisc
+.SH SYNOPSIS
+.B tc qdisc ... dev
+dev
+.B parent
+classid
+.B [ handle
+major:
+.B ] cbs idleslope
+idleslope
+.B sendslope
+sendslope
+.B hicredit
+hicredit
+.B locredit
+locredit
+.B [ offload
+0|1
+.B ]
+
+.SH DESCRIPTION
+The CBS (Credit Based Shaper) qdisc implements the shaping algorithm
+defined by the IEEE 802.1Q-2014 Section 8.6.8.2, which applies a well
+defined rate limiting method to the traffic.
+
+This queueing discipline is intended to be used by TSN (Time Sensitive
+Networking) applications, the CBS parameters are derived directly by
+what is described by the Annex L of the IEEE 802.1Q-2014
+Sepcification. The algorithm and how it affects the latency are
+detailed there.
+
+CBS is meant to be installed under another qdisc that maps packet
+flows to traffic classes, one example is
+.BR mqprio(8).
+
+.SH PARAMETERS
+.TP
+idleslope
+Idleslope is the rate of credits that is accumulated (in kilobits per
+second) when there is at least one packet waiting for transmission.
+Packets are transmitted when the current value of credits is equal or
+greater than zero. When there is no packet to be transmitted the
+amount of credits is set to zero. This is the main tunable of the CBS
+algorithm.
+.TP
+sendslope
+Sendslope is the rate of credits that is depleted (it should be a
+negative number of kilobits per second) when a transmission is
+ocurring. It can be calculated as follows, (IEEE 802.1Q-2014 Section
+8.6.8.2 item g):
+
+sendslope = idleslope - port_transmit_rate
+
+.TP
+hicredit
+Hicredit defines the maximum amount of credits (in bytes) that can be
+accumulated. Hicredit depends on the characteristics of interfering
+traffic, 'max_interference_size' is the maximum size of any burst of
+traffic that can delay the transmission of a frame that is available
+for transmission for this traffic class, (IEEE 802.1Q-2014 Annex L,
+Equation L-3):
+
+hicredit = max_interference_size * (idleslope / port_transmit_rate)
+
+.TP
+locredit
+Locredit is the minimum amount of credits that can be reached. It is a
+function of the traffic flowing through this qdisc (IEEE 802.1Q-2014
+Annex L, Equation L-2):
+
+locredit = max_frame_size * (sendslope / port_transmit_rate)
+
+.TP
+offload
+When
+.B offload
+is 1,
+.BR cbs(8)
+will try to configure the network interface so the CBS algorithm runs
+in the controller. The default is 0.
+
+.SH EXAMPLES
+
+CBS is used to enforce a Quality of Service by limiting the data rate
+of a traffic class, to separate packets into traffic classes the user
+may choose
+.BR mqprio(8),
+and configure it like this:
+
+.EX
+# tc qdisc add dev eth0 handle 100: parent root mqprio num_tc 3 \\
+ map 2 2 1 0 2 2 2 2 2 2 2 2 2 2 2 2 \\
+ queues 1@0 1@1 2@2 \\
+ hw 0
+.EE
+.P
+To replace the current queuing disciple by CBS in the current queueing
+discipline connected to traffic class number 0, issue:
+.P
+.EX
+# tc qdisc replace dev eth0 parent 100:4 cbs \\
+ locredit -1470 hicredit 30 sendslope -980000 idleslope 20000
+.EE
+
+These values are obtained from the following parameters, idleslope is
+20mbit/s, the transmission rate is 1Gbit/s and the maximum interfering
+frame size is 1500 bytes.
+
+.SH AUTHORS
+Vinicius Costa Gomes <vinicius.gomes@intel.com>
--
2.14.2
^ permalink raw reply related [flat|nested] 4+ messages in thread