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/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
* tc_red.c RED maintenance routines.
*
* Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
*/
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <math.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <string.h>
#include "utils.h"
#include "tc_core.h"
#include "tc_util.h"
#include "tc_red.h"
/*
Plog = log(prob/(qmax - qmin))
*/
int tc_red_eval_P(unsigned int qmin, unsigned int qmax, double prob)
{
int i = qmax - qmin;
if (!i)
return 0;
if (i < 0)
return -1;
prob /= i;
for (i = 0; i < 32; i++) {
if (prob > 1.0)
break;
prob *= 2;
}
if (i >= 32)
return -1;
return i;
}
/*
burst + 1 - qmin/avpkt < (1-(1-W)^burst)/W
*/
int tc_red_eval_ewma(unsigned int qmin, unsigned int burst, unsigned int avpkt)
{
int wlog = 1;
double W = 0.5;
double a = (double)burst + 1 - (double)qmin/avpkt;
if (a < 1.0) {
fprintf(stderr, "tc_red_eval_ewma() burst %u is too small ? Try burst %u\n",
burst, 1 + qmin/avpkt);
return -1;
}
for (wlog = 1; wlog < 32; wlog++, W /= 2) {
if (a <= (1 - pow(1-W, burst))/W)
return wlog;
}
return -1;
}
/*
Stab[t>>Scell_log] = -log(1-W) * t/xmit_time
*/
int tc_red_eval_idle_damping(int Wlog, unsigned int avpkt, unsigned int bps, __u8 *sbuf)
{
double xmit_time = tc_calc_xmittime(bps, avpkt);
double lW = -log(1.0 - 1.0/(1<<Wlog))/xmit_time;
double maxtime = 31/lW;
int clog;
int i;
for (clog = 0; clog < 32; clog++) {
if (maxtime/(1<<clog) < 512)
break;
}
if (clog >= 32)
return -1;
sbuf[0] = 0;
for (i = 1; i < 255; i++) {
sbuf[i] = (i<<clog)*lW;
if (sbuf[i] > 31)
sbuf[i] = 31;
}
sbuf[255] = 31;
return clog;
}
void tc_red_print_flags(__u32 flags)
{
if (flags & TC_RED_ECN)
print_bool(PRINT_ANY, "ecn", "ecn ", true);
else
print_bool(PRINT_ANY, "ecn", NULL, false);
if (flags & TC_RED_HARDDROP)
print_bool(PRINT_ANY, "harddrop", "harddrop ", true);
else
print_bool(PRINT_ANY, "harddrop", NULL, false);
if (flags & TC_RED_ADAPTATIVE)
print_bool(PRINT_ANY, "adaptive", "adaptive ", true);
else
print_bool(PRINT_ANY, "adaptive", NULL, false);
if (flags & TC_RED_NODROP)
print_bool(PRINT_ANY, "nodrop", "nodrop ", true);
else
print_bool(PRINT_ANY, "nodrop", NULL, false);
}
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