fq_codel: Fair Queue Codel AQM

Fair Queue Codel packet scheduler

Principles :

- Packets are classified (internal classifier or external) on flows.
- This is a Stochastic model (as we use a hash, several flows might
                              be hashed on same slot)
- Each flow has a CoDel managed queue.
- Flows are linked onto two (Round Robin) lists,
  so that new flows have priority on old ones.

- For a given flow, packets are not reordered (CoDel uses a FIFO)
- head drops only.
- ECN capability is on by default.
- Very low memory footprint (64 bytes per flow)

tc qdisc ... fq_codel [ limit PACKETS ] [ flows number ]
                      [ target TIME ] [ interval TIME ] [ noecn ]
                      [ quantum BYTES ]
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Dave Taht <dave.taht@bufferbloat.net>
Cc: Kathleen Nichols <nichols@pollere.com>
Cc: Van Jacobson <van@pollere.net>
Cc: Tom Herbert <therbert@google.com>
Cc: Matt Mathis <mattmathis@google.com>
Cc: Nandita Dukkipati <nanditad@google.com>
Cc: Maciej Żenczykowski <maze@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Cc: Stephen Hemminger <shemminger@vyatta.com>
Cc: Changli Gao <xiaosuo@gmail.com>

tc/Makefile

@@ -48,6 +48,7 @@ TCMODULES += em_u32.o
 TCMODULES += em_meta.o
 TCMODULES += q_mqprio.o
 TCMODULES += q_codel.o
+TCMODULES += q_fq_codel.o
 
 TCSO :=
 ifeq ($(TC_CONFIG_ATM),y)

tc/q_fq_codel.c

+/*
+ * Fair Queue Codel
+ *
+ *  Copyright (C) 2012 Eric Dumazet <edumazet@google.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions, and the following disclaimer,
+ *    without modification.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The names of the authors may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * Alternatively, provided that this notice is retained in full, this
+ * software may be distributed under the terms of the GNU General
+ * Public License ("GPL") version 2, in which case the provisions of the
+ * GPL apply INSTEAD OF those given above.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
+ * DAMAGE.
+ *
+ */
+
+#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: ... fq_codel [ limit PACKETS ] [ flows NUMBER ]\n");
+	fprintf(stderr, "                    [ target TIME] [ interval TIME ]\n");
+	fprintf(stderr, "                    [ quantum BYTES ] [ [no]ecn ]\n");
+}
+
+static int fq_codel_parse_opt(struct qdisc_util *qu, int argc, char **argv,
+			      struct nlmsghdr *n)
+{
+	unsigned limit = 0;
+	unsigned flows = 0;
+	unsigned target = 0;
+	unsigned interval = 0;
+	unsigned quantum = 0;
+	int ecn = -1;
+	struct rtattr *tail;
+
+	while (argc > 0) {
+		if (strcmp(*argv, "limit") == 0) {
+			NEXT_ARG();
+			if (get_unsigned(&limit, *argv, 0)) {
+				fprintf(stderr, "Illegal \"limit\"\n");
+				return -1;
+			}
+		} else if (strcmp(*argv, "flows") == 0) {
+			NEXT_ARG();
+			if (get_unsigned(&flows, *argv, 0)) {
+				fprintf(stderr, "Illegal \"flows\"\n");
+				return -1;
+			}
+		} else if (strcmp(*argv, "quantum") == 0) {
+			NEXT_ARG();
+			if (get_unsigned(&quantum, *argv, 0)) {
+				fprintf(stderr, "Illegal \"quantum\"\n");
+				return -1;
+			}
+		} else if (strcmp(*argv, "target") == 0) {
+			NEXT_ARG();
+			if (get_time(&target, *argv)) {
+				fprintf(stderr, "Illegal \"target\"\n");
+				return -1;
+			}
+		} else if (strcmp(*argv, "interval") == 0) {
+			NEXT_ARG();
+			if (get_time(&interval, *argv)) {
+				fprintf(stderr, "Illegal \"interval\"\n");
+				return -1;
+			}
+		} else if (strcmp(*argv, "ecn") == 0) {
+			ecn = 1;
+		} else if (strcmp(*argv, "noecn") == 0) {
+			ecn = 0;
+		} else if (strcmp(*argv, "help") == 0) {
+			explain();
+			return -1;
+		} else {
+			fprintf(stderr, "What is \"%s\"?\n", *argv);
+			explain();
+			return -1;
+		}
+		argc--; argv++;
+	}
+
+	tail = NLMSG_TAIL(n);
+	addattr_l(n, 1024, TCA_OPTIONS, NULL, 0);
+	if (limit)
+		addattr_l(n, 1024, TCA_FQ_CODEL_LIMIT, &limit, sizeof(limit));
+	if (flows)
+		addattr_l(n, 1024, TCA_FQ_CODEL_FLOWS, &flows, sizeof(flows));
+	if (quantum)
+		addattr_l(n, 1024, TCA_FQ_CODEL_QUANTUM, &quantum, sizeof(quantum));
+	if (interval)
+		addattr_l(n, 1024, TCA_FQ_CODEL_INTERVAL, &interval, sizeof(interval));
+	if (target)
+		addattr_l(n, 1024, TCA_FQ_CODEL_TARGET, &target, sizeof(target));
+	if (ecn != -1)
+		addattr_l(n, 1024, TCA_FQ_CODEL_ECN, &ecn, sizeof(ecn));
+	tail->rta_len = (void *) NLMSG_TAIL(n) - (void *) tail;
+	return 0;
+}
+
+static int fq_codel_print_opt(struct qdisc_util *qu, FILE *f, struct rtattr *opt)
+{
+	struct rtattr *tb[TCA_FQ_CODEL_MAX + 1];
+	unsigned limit;
+	unsigned flows;
+	unsigned interval;
+	unsigned target;
+	unsigned ecn;
+	unsigned quantum;
+	SPRINT_BUF(b1);
+
+	if (opt == NULL)
+		return 0;
+
+	parse_rtattr_nested(tb, TCA_FQ_CODEL_MAX, opt);
+
+	if (tb[TCA_FQ_CODEL_LIMIT] &&
+	    RTA_PAYLOAD(tb[TCA_FQ_CODEL_LIMIT]) >= sizeof(__u32)) {
+		limit = rta_getattr_u32(tb[TCA_FQ_CODEL_LIMIT]);
+		fprintf(f, "limit %up ", limit);
+	}
+	if (tb[TCA_FQ_CODEL_FLOWS] &&
+	    RTA_PAYLOAD(tb[TCA_FQ_CODEL_FLOWS]) >= sizeof(__u32)) {
+		flows = rta_getattr_u32(tb[TCA_FQ_CODEL_FLOWS]);
+		fprintf(f, "flows %u ", flows);
+	}
+	if (tb[TCA_FQ_CODEL_QUANTUM] &&
+	    RTA_PAYLOAD(tb[TCA_FQ_CODEL_QUANTUM]) >= sizeof(__u32)) {
+		quantum = rta_getattr_u32(tb[TCA_FQ_CODEL_QUANTUM]);
+		fprintf(f, "quantum %u ", quantum);
+	}
+	if (tb[TCA_FQ_CODEL_TARGET] &&
+	    RTA_PAYLOAD(tb[TCA_FQ_CODEL_TARGET]) >= sizeof(__u32)) {
+		target = rta_getattr_u32(tb[TCA_FQ_CODEL_TARGET]);
+		fprintf(f, "target %s ", sprint_time(target, b1));
+	}
+	if (tb[TCA_FQ_CODEL_INTERVAL] &&
+	    RTA_PAYLOAD(tb[TCA_FQ_CODEL_INTERVAL]) >= sizeof(__u32)) {
+		interval = rta_getattr_u32(tb[TCA_FQ_CODEL_INTERVAL]);
+		fprintf(f, "interval %s ", sprint_time(interval, b1));
+	}
+	if (tb[TCA_FQ_CODEL_ECN] &&
+	    RTA_PAYLOAD(tb[TCA_FQ_CODEL_ECN]) >= sizeof(__u32)) {
+		ecn = rta_getattr_u32(tb[TCA_FQ_CODEL_ECN]);
+		if (ecn)
+			fprintf(f, "ecn ");
+	}
+
+	return 0;
+}
+
+static int fq_codel_print_xstats(struct qdisc_util *qu, FILE *f,
+				 struct rtattr *xstats)
+{
+	struct tc_fq_codel_xstats *st;
+	SPRINT_BUF(b1);
+
+	if (xstats == NULL)
+		return 0;
+
+	if (RTA_PAYLOAD(xstats) < sizeof(*st))
+		return -1;
+
+	st = RTA_DATA(xstats);
+	if (st->type == TCA_FQ_CODEL_XSTATS_QDISC) {
+		fprintf(f, "  maxpacket %u drop_overlimit %u new_flow_count %u ecn_mark %u",
+			st->qdisc_stats.maxpacket,
+			st->qdisc_stats.drop_overlimit,
+			st->qdisc_stats.new_flow_count,
+			st->qdisc_stats.ecn_mark);
+		fprintf(f, "\n  new_flows_len %u old_flows_len %u",
+			st->qdisc_stats.new_flows_len,
+			st->qdisc_stats.old_flows_len);
+	}
+	if (st->type == TCA_FQ_CODEL_XSTATS_CLASS) {
+		fprintf(f, "  deficit %d count %u lastcount %u ldelay %s",
+			st->class_stats.deficit,
+			st->class_stats.count,
+			st->class_stats.lastcount,
+			sprint_time(st->class_stats.ldelay, b1));
+		if (st->class_stats.dropping) {
+			fprintf(f, " dropping");
+			if (st->class_stats.drop_next < 0)
+				fprintf(f, " drop_next -%s",
+					sprint_time(-st->class_stats.drop_next, b1));
+			else
+				fprintf(f, " drop_next %s",
+					sprint_time(st->class_stats.drop_next, b1));
+		}
+	}
+	return 0;
+
+}
+
+struct qdisc_util fq_codel_qdisc_util = {
+	.id		= "fq_codel",
+	.parse_qopt	= fq_codel_parse_opt,
+	.print_qopt	= fq_codel_print_opt,
+	.print_xstats	= fq_codel_print_xstats,
+};