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41f6004139
This patch adds detailed documentation for HFSC scheduler. It roughly follows HFSC paper, but tries to not rely too much on math side of things. Post-paper/Linux specific subjects (timer resolution, ul service curve, etc.) are also discussed. I've read it many times over, but it's a lengthy chunk of text - so try to be understanding in case I made some mistakes. tc-hfsc(7): explains algorithm in detail (very long) tc-hfsc(8): explains command line options briefly tc(8): adds references to new man pages Makefile: adds man7 directory to install target q_hfsc.c: minimal help text changes, consistency with tc-hfsc(8) Signed-off-by: Mike Frysinger <vapier@gentoo.org>
411 lines
8.6 KiB
C
411 lines
8.6 KiB
C
/*
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* q_hfsc.c HFSC.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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* Authors: Patrick McHardy, <kaber@trash.net>
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*
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <syslog.h>
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#include <fcntl.h>
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#include <sys/socket.h>
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#include <netinet/in.h>
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#include <arpa/inet.h>
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#include <string.h>
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#include <math.h>
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#include "utils.h"
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#include "tc_util.h"
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static int hfsc_get_sc(int *, char ***, struct tc_service_curve *);
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static void
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explain_qdisc(void)
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{
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fprintf(stderr,
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"Usage: ... hfsc [ default CLASSID ]\n"
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"\n"
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" default: default class for unclassified packets\n"
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);
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}
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static void
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explain_class(void)
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{
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fprintf(stderr,
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"Usage: ... hfsc [ [ rt SC ] [ ls SC ] | [ sc SC ] ] [ ul SC ]\n"
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"\n"
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"SC := [ [ m1 BPS ] d SEC ] m2 BPS\n"
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"\n"
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" m1 : slope of first segment\n"
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" d : x-coordinate of intersection\n"
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" m2 : slope of second segment\n"
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"\n"
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"Alternative format:\n"
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"\n"
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"SC := [ [ umax BYTE ] dmax SEC ] rate BPS\n"
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"\n"
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" umax : maximum unit of work\n"
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" dmax : maximum delay\n"
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" rate : rate\n"
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"\n"
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"Remarks:\n"
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" - at least one of 'rt', 'ls' or 'sc' must be specified\n"
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" - 'ul' can only be specified with 'ls' or 'sc'\n"
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"\n"
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);
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}
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static void
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explain1(char *arg)
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{
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fprintf(stderr, "HFSC: Illegal \"%s\"\n", arg);
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}
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static int
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hfsc_parse_opt(struct qdisc_util *qu, int argc, char **argv, struct nlmsghdr *n)
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{
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struct tc_hfsc_qopt qopt;
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memset(&qopt, 0, sizeof(qopt));
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while (argc > 0) {
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if (matches(*argv, "default") == 0) {
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NEXT_ARG();
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if (qopt.defcls != 0) {
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fprintf(stderr, "HFSC: Double \"default\"\n");
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return -1;
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}
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if (get_u16(&qopt.defcls, *argv, 16) < 0) {
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explain1("default");
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return -1;
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}
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} else if (matches(*argv, "help") == 0) {
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explain_qdisc();
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return -1;
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} else {
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fprintf(stderr, "HFSC: What is \"%s\" ?\n", *argv);
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explain_qdisc();
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return -1;
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}
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argc--, argv++;
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}
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addattr_l(n, 1024, TCA_OPTIONS, &qopt, sizeof(qopt));
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return 0;
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}
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static int
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hfsc_print_opt(struct qdisc_util *qu, FILE *f, struct rtattr *opt)
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{
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struct tc_hfsc_qopt *qopt;
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if (opt == NULL)
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return 0;
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if (RTA_PAYLOAD(opt) < sizeof(*qopt))
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return -1;
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qopt = RTA_DATA(opt);
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if (qopt->defcls != 0)
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fprintf(f, "default %x ", qopt->defcls);
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return 0;
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}
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static int
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hfsc_print_xstats(struct qdisc_util *qu, FILE *f, struct rtattr *xstats)
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{
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struct tc_hfsc_stats *st;
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if (xstats == NULL)
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return 0;
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if (RTA_PAYLOAD(xstats) < sizeof(*st))
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return -1;
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st = RTA_DATA(xstats);
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fprintf(f, " period %u ", st->period);
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if (st->work != 0)
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fprintf(f, "work %llu bytes ", (unsigned long long) st->work);
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if (st->rtwork != 0)
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fprintf(f, "rtwork %llu bytes ", (unsigned long long) st->rtwork);
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fprintf(f, "level %u ", st->level);
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fprintf(f, "\n");
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return 0;
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}
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static int
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hfsc_parse_class_opt(struct qdisc_util *qu, int argc, char **argv,
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struct nlmsghdr *n)
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{
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struct tc_service_curve rsc, fsc, usc;
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int rsc_ok, fsc_ok, usc_ok;
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struct rtattr *tail;
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memset(&rsc, 0, sizeof(rsc));
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memset(&fsc, 0, sizeof(fsc));
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memset(&usc, 0, sizeof(usc));
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rsc_ok = fsc_ok = usc_ok = 0;
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while (argc > 0) {
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if (matches(*argv, "rt") == 0) {
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NEXT_ARG();
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if (hfsc_get_sc(&argc, &argv, &rsc) < 0) {
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explain1("rt");
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return -1;
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}
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rsc_ok = 1;
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} else if (matches(*argv, "ls") == 0) {
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NEXT_ARG();
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if (hfsc_get_sc(&argc, &argv, &fsc) < 0) {
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explain1("ls");
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return -1;
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}
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fsc_ok = 1;
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} else if (matches(*argv, "sc") == 0) {
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NEXT_ARG();
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if (hfsc_get_sc(&argc, &argv, &rsc) < 0) {
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explain1("sc");
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return -1;
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}
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memcpy(&fsc, &rsc, sizeof(fsc));
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rsc_ok = 1;
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fsc_ok = 1;
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} else if (matches(*argv, "ul") == 0) {
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NEXT_ARG();
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if (hfsc_get_sc(&argc, &argv, &usc) < 0) {
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explain1("ul");
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return -1;
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}
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usc_ok = 1;
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} else if (matches(*argv, "help") == 0) {
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explain_class();
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return -1;
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} else {
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fprintf(stderr, "HFSC: What is \"%s\" ?\n", *argv);
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explain_class();
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return -1;
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}
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argc--, argv++;
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}
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if (!(rsc_ok || fsc_ok || usc_ok)) {
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fprintf(stderr, "HFSC: no parameters given\n");
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explain_class();
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return -1;
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}
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if (usc_ok && !fsc_ok) {
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fprintf(stderr, "HFSC: Upper-limit Service Curve without "
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"Link-Share Service Curve\n");
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explain_class();
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return -1;
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}
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tail = NLMSG_TAIL(n);
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addattr_l(n, 1024, TCA_OPTIONS, NULL, 0);
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if (rsc_ok)
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addattr_l(n, 1024, TCA_HFSC_RSC, &rsc, sizeof(rsc));
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if (fsc_ok)
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addattr_l(n, 1024, TCA_HFSC_FSC, &fsc, sizeof(fsc));
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if (usc_ok)
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addattr_l(n, 1024, TCA_HFSC_USC, &usc, sizeof(usc));
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tail->rta_len = (void *) NLMSG_TAIL(n) - (void *) tail;
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return 0;
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}
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static void
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hfsc_print_sc(FILE *f, char *name, struct tc_service_curve *sc)
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{
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SPRINT_BUF(b1);
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fprintf(f, "%s ", name);
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fprintf(f, "m1 %s ", sprint_rate(sc->m1, b1));
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fprintf(f, "d %s ", sprint_time(tc_core_ktime2time(sc->d), b1));
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fprintf(f, "m2 %s ", sprint_rate(sc->m2, b1));
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}
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static int
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hfsc_print_class_opt(struct qdisc_util *qu, FILE *f, struct rtattr *opt)
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{
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struct rtattr *tb[TCA_HFSC_MAX+1];
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struct tc_service_curve *rsc = NULL, *fsc = NULL, *usc = NULL;
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if (opt == NULL)
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return 0;
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parse_rtattr_nested(tb, TCA_HFSC_MAX, opt);
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if (tb[TCA_HFSC_RSC]) {
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if (RTA_PAYLOAD(tb[TCA_HFSC_RSC]) < sizeof(*rsc))
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fprintf(stderr, "HFSC: truncated realtime option\n");
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else
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rsc = RTA_DATA(tb[TCA_HFSC_RSC]);
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}
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if (tb[TCA_HFSC_FSC]) {
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if (RTA_PAYLOAD(tb[TCA_HFSC_FSC]) < sizeof(*fsc))
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fprintf(stderr, "HFSC: truncated linkshare option\n");
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else
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fsc = RTA_DATA(tb[TCA_HFSC_FSC]);
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}
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if (tb[TCA_HFSC_USC]) {
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if (RTA_PAYLOAD(tb[TCA_HFSC_USC]) < sizeof(*usc))
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fprintf(stderr, "HFSC: truncated upperlimit option\n");
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else
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usc = RTA_DATA(tb[TCA_HFSC_USC]);
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}
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if (rsc != NULL && fsc != NULL &&
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memcmp(rsc, fsc, sizeof(*rsc)) == 0)
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hfsc_print_sc(f, "sc", rsc);
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else {
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if (rsc != NULL)
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hfsc_print_sc(f, "rt", rsc);
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if (fsc != NULL)
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hfsc_print_sc(f, "ls", fsc);
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}
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if (usc != NULL)
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hfsc_print_sc(f, "ul", usc);
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return 0;
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}
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struct qdisc_util hfsc_qdisc_util = {
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.id = "hfsc",
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.parse_qopt = hfsc_parse_opt,
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.print_qopt = hfsc_print_opt,
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.print_xstats = hfsc_print_xstats,
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.parse_copt = hfsc_parse_class_opt,
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.print_copt = hfsc_print_class_opt,
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};
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static int
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hfsc_get_sc1(int *argcp, char ***argvp, struct tc_service_curve *sc)
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{
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char **argv = *argvp;
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int argc = *argcp;
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unsigned int m1 = 0, d = 0, m2 = 0;
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if (matches(*argv, "m1") == 0) {
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NEXT_ARG();
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if (get_rate(&m1, *argv) < 0) {
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explain1("m1");
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return -1;
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}
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NEXT_ARG();
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}
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if (matches(*argv, "d") == 0) {
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NEXT_ARG();
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if (get_time(&d, *argv) < 0) {
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explain1("d");
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return -1;
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}
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NEXT_ARG();
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}
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if (matches(*argv, "m2") == 0) {
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NEXT_ARG();
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if (get_rate(&m2, *argv) < 0) {
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explain1("m2");
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return -1;
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}
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} else
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return -1;
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sc->m1 = m1;
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sc->d = tc_core_time2ktime(d);
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sc->m2 = m2;
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*argvp = argv;
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*argcp = argc;
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return 0;
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}
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static int
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hfsc_get_sc2(int *argcp, char ***argvp, struct tc_service_curve *sc)
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{
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char **argv = *argvp;
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int argc = *argcp;
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unsigned int umax = 0, dmax = 0, rate = 0;
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if (matches(*argv, "umax") == 0) {
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NEXT_ARG();
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if (get_size(&umax, *argv) < 0) {
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explain1("umax");
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return -1;
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}
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NEXT_ARG();
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}
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if (matches(*argv, "dmax") == 0) {
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NEXT_ARG();
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if (get_time(&dmax, *argv) < 0) {
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explain1("dmax");
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return -1;
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}
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NEXT_ARG();
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}
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if (matches(*argv, "rate") == 0) {
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NEXT_ARG();
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if (get_rate(&rate, *argv) < 0) {
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explain1("rate");
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return -1;
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}
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} else
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return -1;
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if (umax != 0 && dmax == 0) {
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fprintf(stderr, "HFSC: umax given but dmax is zero.\n");
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return -1;
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}
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if (dmax != 0 && ceil(1.0 * umax * TIME_UNITS_PER_SEC / dmax) > rate) {
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/*
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* concave curve, slope of first segment is umax/dmax,
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* intersection is at dmax
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*/
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sc->m1 = ceil(1.0 * umax * TIME_UNITS_PER_SEC / dmax); /* in bps */
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sc->d = tc_core_time2ktime(dmax);
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sc->m2 = rate;
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} else {
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/*
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* convex curve, slope of first segment is 0, intersection
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* is at dmax - umax / rate
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*/
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sc->m1 = 0;
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sc->d = tc_core_time2ktime(ceil(dmax - umax * TIME_UNITS_PER_SEC / rate));
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sc->m2 = rate;
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}
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*argvp = argv;
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*argcp = argc;
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return 0;
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}
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static int
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hfsc_get_sc(int *argcp, char ***argvp, struct tc_service_curve *sc)
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{
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if (hfsc_get_sc1(argcp, argvp, sc) < 0 &&
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hfsc_get_sc2(argcp, argvp, sc) < 0)
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return -1;
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if (sc->m1 == 0 && sc->m2 == 0) {
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fprintf(stderr, "HFSC: Service Curve has two zero slopes\n");
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return -1;
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}
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return 0;
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}
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