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[DCCP] loss_interval: Move ccid3_hc_rx_update_li to loss_interval
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Renaming it to dccp_li_update_li.

Also based on previous work by Ian McDonald.

Signed-off-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
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Arnaldo Carvalho de Melo authored and David S. Miller committed Jul 11, 2007
1 parent 878ac60 commit cc0a910
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Showing 3 changed files with 176 additions and 170 deletions.
179 changes: 9 additions & 170 deletions net/dccp/ccids/ccid3.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -819,167 +819,6 @@ static int ccid3_hc_rx_insert_options(struct sock *sk, struct sk_buff *skb)
return 0;
}

/* calculate first loss interval
*
* returns estimated loss interval in usecs */

static u32 ccid3_hc_rx_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;
ccid3_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);

ccid3_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;
}

static void ccid3_hc_rx_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 =
ccid3_hc_rx_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;
}
}

static int ccid3_hc_rx_detect_loss(struct sock *sk,
struct dccp_rx_hist_entry *packet)
{
Expand All @@ -1005,15 +844,15 @@ static int ccid3_hc_rx_detect_loss(struct sock *sk,
while (dccp_delta_seqno(hcrx->ccid3hcrx_seqno_nonloss, seqno)
> TFRC_RECV_NUM_LATE_LOSS) {
loss = 1;
ccid3_hc_rx_update_li(sk, ccid3_li_hist,
&hcrx->ccid3hcrx_li_hist,
&hcrx->ccid3hcrx_hist,
&hcrx->ccid3hcrx_tstamp_last_feedback,
hcrx->ccid3hcrx_s,
hcrx->ccid3hcrx_bytes_recv,
hcrx->ccid3hcrx_x_recv,
hcrx->ccid3hcrx_seqno_nonloss,
hcrx->ccid3hcrx_ccval_nonloss);
dccp_li_update_li(sk, ccid3_li_hist,
&hcrx->ccid3hcrx_li_hist,
&hcrx->ccid3hcrx_hist,
&hcrx->ccid3hcrx_tstamp_last_feedback,
hcrx->ccid3hcrx_s,
hcrx->ccid3hcrx_bytes_recv,
hcrx->ccid3hcrx_x_recv,
hcrx->ccid3hcrx_seqno_nonloss,
hcrx->ccid3hcrx_ccval_nonloss);
tmp_seqno = hcrx->ccid3hcrx_seqno_nonloss;
dccp_inc_seqno(&tmp_seqno);
hcrx->ccid3hcrx_seqno_nonloss = tmp_seqno;
Expand Down
160 changes: 160 additions & 0 deletions net/dccp/ccids/lib/loss_interval.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -15,6 +15,8 @@
#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)
{
Expand Down Expand Up @@ -141,3 +143,161 @@ int dccp_li_hist_interval_new(struct dccp_li_hist *hist,
}

EXPORT_SYMBOL_GPL(dccp_li_hist_interval_new);

/* 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);
7 changes: 7 additions & 0 deletions net/dccp/ccids/lib/loss_interval.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -54,4 +54,11 @@ extern u32 dccp_li_hist_calc_i_mean(struct list_head *list);

extern int dccp_li_hist_interval_new(struct dccp_li_hist *hist,
struct list_head *list, const u64 seq_loss, const u8 win_loss);

extern 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);
#endif /* _DCCP_LI_HIST_ */

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