/*
* net/dccp/ccids/lib/loss_interval.c
*
* Copyright (c) 2005-7 The University of Waikato, Hamilton, New Zealand.
* Copyright (c) 2005-7 Ian McDonald <ian.mcdonald@jandi.co.nz>
* Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@conectiva.com.br>
*
* 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.
*/
#include <linux/module.h>
#include <net/sock.h>
#include "../../dccp.h"
#include "loss_interval.h"
#include "packet_history.h"
#include "tfrc.h"
struct dccp_li_hist *dccp_li_hist_new(const char *name)
{
struct dccp_li_hist *hist = kmalloc(sizeof(*hist), GFP_ATOMIC);
static const char dccp_li_hist_mask[] = "li_hist_%s";
char *slab_name;
if (hist == NULL)
goto out;
slab_name = kmalloc(strlen(name) + sizeof(dccp_li_hist_mask) - 1,
GFP_ATOMIC);
if (slab_name == NULL)
goto out_free_hist;
sprintf(slab_name, dccp_li_hist_mask, name);
hist->dccplih_slab = kmem_cache_create(slab_name,
sizeof(struct dccp_li_hist_entry),
0, SLAB_HWCACHE_ALIGN,
NULL, NULL);
if (hist->dccplih_slab == NULL)
goto out_free_slab_name;
out:
return hist;
out_free_slab_name:
kfree(slab_name);
out_free_hist:
kfree(hist);
hist = NULL;
goto out;
}
EXPORT_SYMBOL_GPL(dccp_li_hist_new);
void dccp_li_hist_delete(struct dccp_li_hist *hist)
{
const char* name = kmem_cache_name(hist->dccplih_slab);
kmem_cache_destroy(hist->dccplih_slab);
kfree(name);
kfree(hist);
}
EXPORT_SYMBOL_GPL(dccp_li_hist_delete);
void dccp_li_hist_purge(struct dccp_li_hist *hist, struct list_head *list)
{
struct dccp_li_hist_entry *entry, *next;
list_for_each_entry_safe(entry, next, list, dccplih_node) {
list_del_init(&entry->dccplih_node);
kmem_cache_free(hist->dccplih_slab, entry);
}
}
EXPORT_SYMBOL_GPL(dccp_li_hist_purge);
/* Weights used to calculate loss event rate */
/*
* These are integers as per section 8 of RFC3448. We can then divide by 4 *
* when we use it.
*/
static const int dccp_li_hist_w[DCCP_LI_HIST_IVAL_F_LENGTH] = {
4, 4, 4, 4, 3, 2, 1, 1,
};
u32 dccp_li_hist_calc_i_mean(struct list_head *list)
{
struct dccp_li_hist_entry *li_entry, *li_next;
int i = 0;
u32 i_tot;
u32 i_tot0 = 0;
u32 i_tot1 = 0;
u32 w_tot = 0;
list_for_each_entry_safe(li_entry, li_next, list, dccplih_node) {
if (li_entry->dccplih_interval != ~0U) {
i_tot0 += li_entry->dccplih_interval * dccp_li_hist_w[i];
w_tot += dccp_li_hist_w[i];
if (i != 0)
i_tot1 += li_entry->dccplih_interval * dccp_li_hist_w[i - 1];
}
if (++i > DCCP_LI_HIST_IVAL_F_LENGTH)
break;
}
if (i != DCCP_LI_HIST_IVAL_F_LENGTH)
return 0;
i_tot = max(i_tot0, i_tot1);
if (!w_tot) {
DCCP_WARN("w_tot = 0\n");
return 1;
}
return i_tot / w_tot;
}
EXPORT_SYMBOL_GPL(dccp_li_hist_calc_i_mean);
static int dccp_li_hist_interval_new(struct dccp_li_hist *hist,
struct list_head *list,
const u64 seq_loss, const u8 win_loss)
{
struct dccp_li_hist_entry *entry;
int i;
for (i = 0; i < DCCP_LI_HIST_IVAL_F_LENGTH; i++) {
entry = dccp_li_hist_entry_new(hist, GFP_ATOMIC);
if (entry == NULL) {
dccp_li_hist_purge(hist, list);
DCCP_BUG("loss interval list entry is NULL");
return 0;
}
entry->dccplih_interval = ~0;
list_add(&entry->dccplih_node, list);
}
entry->dccplih_seqno = seq_loss;
entry->dccplih_win_count = win_loss;
return 1;
}
/* calculate first loss interval
*
* returns estimated loss interval in usecs */
static u32 dccp_li_calc_first_li(struct sock *sk,
struct list_head *hist_list,
struct timeval *last_feedback,
u16 s, u32 bytes_recv,
u32 previous_x_recv)
{
struct dccp_rx_hist_entry *entry, *next, *tail = NULL;
u32 x_recv, p;
suseconds_t rtt, delta;
struct timeval tstamp = { 0, 0 };
int interval = 0;
int win_count = 0;
int step = 0;
u64 fval;
list_for_each_entry_safe(entry, next, hist_list, dccphrx_node) {
if (dccp_rx_hist_entry_data_packet(entry)) {
tail = entry;
switch (step) {
case 0:
tstamp = entry->dccphrx_tstamp;
win_count = entry->dccphrx_ccval;
step = 1;
break;
case 1:
interval = win_count - entry->dccphrx_ccval;
if (interval < 0)
interval += TFRC_WIN_COUNT_LIMIT;
if (interval > 4)
goto found;
break;
}
}
}
if (unlikely(step == 0)) {
DCCP_WARN("%s(%p), packet history has no data packets!\n",
dccp_role(sk), sk);
return ~0;
}
if (unlikely(interval == 0)) {
DCCP_WARN("%s(%p), Could not find a win_count interval > 0."
"Defaulting to 1\n", dccp_role(sk), sk);
interval = 1;
}
found:
if (!tail) {
DCCP_CRIT("tail is null\n");
return ~0;
}
delta = timeval_delta(&tstamp, &tail->dccphrx_tstamp);
DCCP_BUG_ON(delta < 0);
rtt = delta * 4 / interval;
dccp_pr_debug("%s(%p), approximated RTT to %dus\n",
dccp_role(sk), sk, (int)rtt);
/*
* Determine the length of the first loss interval via inverse lookup.
* Assume that X_recv can be computed by the throughput equation
* s
* X_recv = --------
* R * fval
* Find some p such that f(p) = fval; return 1/p [RFC 3448, 6.3.1].
*/
if (rtt == 0) { /* would result in divide-by-zero */
DCCP_WARN("RTT==0\n");
return ~0;
}
dccp_timestamp(sk, &tstamp);
delta = timeval_delta(&tstamp, last_feedback);
DCCP_BUG_ON(delta <= 0);
x_recv = scaled_div32(bytes_recv, delta);
if (x_recv == 0) { /* would also trigger divide-by-zero */
DCCP_WARN("X_recv==0\n");
if (previous_x_recv == 0) {
DCCP_BUG("stored value of X_recv is zero");
return ~0;
}
x_recv = previous_x_recv;
}
fval = scaled_div(s, rtt);
fval = scaled_div32(fval, x_recv);
p = tfrc_calc_x_reverse_lookup(fval);
dccp_pr_debug("%s(%p), receive rate=%u bytes/s, implied "
"loss rate=%u\n", dccp_role(sk), sk, x_recv, p);
if (p == 0)
return ~0;
else
return 1000000 / p;
}
void dccp_li_update_li(struct sock *sk, struct dccp_li_hist *li_hist,
struct list_head *li_hist_list,
struct list_head *hist_list,
struct timeval *last_feedback, u16 s, u32 bytes_recv,
u32 previous_x_recv, u64 seq_loss, u8 win_loss)
{
struct dccp_li_hist_entry *head;
u64 seq_temp;
if (list_empty(li_hist_list)) {
if (!dccp_li_hist_interval_new(li_hist, li_hist_list,
seq_loss, win_loss))
return;
head = list_entry(li_hist_list->next, struct dccp_li_hist_entry,
dccplih_node);
head->dccplih_interval = dccp_li_calc_first_li(sk, hist_list,
last_feedback,
s, bytes_recv,
previous_x_recv);
} else {
struct dccp_li_hist_entry *entry;
struct list_head *tail;
head = list_entry(li_hist_list->next, struct dccp_li_hist_entry,
dccplih_node);
/* FIXME win count check removed as was wrong */
/* should make this check with receive history */
/* and compare there as per section 10.2 of RFC4342 */
/* new loss event detected */
/* calculate last interval length */
seq_temp = dccp_delta_seqno(head->dccplih_seqno, seq_loss);
entry = dccp_li_hist_entry_new(li_hist, GFP_ATOMIC);
if (entry == NULL) {
DCCP_BUG("out of memory - can not allocate entry");
return;
}
list_add(&entry->dccplih_node, li_hist_list);
tail = li_hist_list->prev;
list_del(tail);
kmem_cache_free(li_hist->dccplih_slab, tail);
/* Create the newest interval */
entry->dccplih_seqno = seq_loss;
entry->dccplih_interval = seq_temp;
entry->dccplih_win_count = win_loss;
}
}
EXPORT_SYMBOL_GPL(dccp_li_update_li);
