/*
* net/dccp/ccids/lib/loss_interval.c
*
+ * Copyright (c) 2007 The University of Aberdeen, Scotland, UK
* 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>
* 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"
-#define DCCP_LI_HIST_IVAL_F_LENGTH 8
-
-struct dccp_li_hist_entry {
- struct list_head dccplih_node;
- u64 dccplih_seqno:48,
- dccplih_win_count:4;
- u32 dccplih_interval;
-};
+static struct kmem_cache *tfrc_lh_slab __read_mostly;
+/* Loss Interval weights from [RFC 3448, 5.4], scaled by 10 */
+static const int tfrc_lh_weights[NINTERVAL] = { 10, 10, 10, 10, 8, 6, 4, 2 };
-static struct kmem_cache *dccp_li_cachep __read_mostly;
-
-static inline struct dccp_li_hist_entry *dccp_li_hist_entry_new(const gfp_t prio)
+/* implements LIFO semantics on the array */
+static inline u8 LIH_INDEX(const u8 ctr)
{
- return kmem_cache_alloc(dccp_li_cachep, prio);
+ return (LIH_SIZE - 1 - (ctr % LIH_SIZE));
}
-static inline void dccp_li_hist_entry_delete(struct dccp_li_hist_entry *entry)
+/* the `counter' index always points at the next entry to be populated */
+static inline struct tfrc_loss_interval *tfrc_lh_peek(struct tfrc_loss_hist *lh)
{
- if (entry != NULL)
- kmem_cache_free(dccp_li_cachep, entry);
+ return lh->counter ? lh->ring[LIH_INDEX(lh->counter - 1)] : NULL;
}
-void dccp_li_hist_purge(struct list_head *list)
+/* given i with 0 <= i <= k, return I_i as per the rfc3448bis notation */
+static inline u32 tfrc_lh_get_interval(struct tfrc_loss_hist *lh, const u8 i)
{
- 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(dccp_li_cachep, entry);
- }
+ BUG_ON(i >= lh->counter);
+ return lh->ring[LIH_INDEX(lh->counter - i - 1)]->li_length;
}
-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.
+ * On-demand allocation and de-allocation of entries
*/
-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)
+static struct tfrc_loss_interval *tfrc_lh_demand_next(struct tfrc_loss_hist *lh)
{
- 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;
+ if (lh->ring[LIH_INDEX(lh->counter)] == NULL)
+ lh->ring[LIH_INDEX(lh->counter)] = kmem_cache_alloc(tfrc_lh_slab,
+ GFP_ATOMIC);
+ return lh->ring[LIH_INDEX(lh->counter)];
}
-EXPORT_SYMBOL_GPL(dccp_li_hist_calc_i_mean);
-
-static int dccp_li_hist_interval_new(struct list_head *list,
- const u64 seq_loss, const u8 win_loss)
+void tfrc_lh_cleanup(struct tfrc_loss_hist *lh)
{
- 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(GFP_ATOMIC);
- if (entry == NULL) {
- dccp_li_hist_purge(list);
- DCCP_BUG("loss interval list entry is NULL");
- return 0;
+ if (!tfrc_lh_is_initialised(lh))
+ return;
+
+ for (lh->counter = 0; lh->counter < LIH_SIZE; lh->counter++)
+ if (lh->ring[LIH_INDEX(lh->counter)] != NULL) {
+ kmem_cache_free(tfrc_lh_slab,
+ lh->ring[LIH_INDEX(lh->counter)]);
+ lh->ring[LIH_INDEX(lh->counter)] = NULL;
}
- entry->dccplih_interval = ~0;
- list_add(&entry->dccplih_node, list);
- }
-
- entry->dccplih_seqno = seq_loss;
- entry->dccplih_win_count = win_loss;
- return 1;
}
+EXPORT_SYMBOL_GPL(tfrc_lh_cleanup);
-/* 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)
+static void tfrc_lh_calc_i_mean(struct tfrc_loss_hist *lh)
{
- 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;
+ u32 i_i, i_tot0 = 0, i_tot1 = 0, w_tot = 0;
+ int i, k = tfrc_lh_length(lh) - 1; /* k is as in rfc3448bis, 5.4 */
- list_for_each_entry_safe(entry, next, hist_list, dccphrx_node) {
- if (dccp_rx_hist_entry_data_packet(entry)) {
- tail = entry;
+ for (i=0; i <= k; i++) {
+ i_i = tfrc_lh_get_interval(lh, i);
- 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 (i < k) {
+ i_tot0 += i_i * tfrc_lh_weights[i];
+ w_tot += tfrc_lh_weights[i];
}
+ if (i > 0)
+ i_tot1 += i_i * tfrc_lh_weights[i-1];
}
- 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);
+ BUG_ON(w_tot == 0);
+ lh->i_mean = max(i_tot0, i_tot1) / w_tot;
+}
- rtt = delta * 4 / interval;
- dccp_pr_debug("%s(%p), approximated RTT to %dus\n",
- dccp_role(sk), sk, (int)rtt);
+/**
+ * tfrc_lh_update_i_mean - Update the `open' loss interval I_0
+ * For recomputing p: returns `true' if p > p_prev <=> 1/p < 1/p_prev
+ */
+u8 tfrc_lh_update_i_mean(struct tfrc_loss_hist *lh, struct sk_buff *skb)
+{
+ struct tfrc_loss_interval *cur = tfrc_lh_peek(lh);
+ u32 old_i_mean = lh->i_mean;
+ s64 length;
- /*
- * 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;
- }
+ if (cur == NULL) /* not initialised */
+ return 0;
- dccp_timestamp(sk, &tstamp);
- delta = timeval_delta(&tstamp, last_feedback);
- DCCP_BUG_ON(delta <= 0);
+ length = dccp_delta_seqno(cur->li_seqno, DCCP_SKB_CB(skb)->dccpd_seq);
- 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;
- }
+ if (length - cur->li_length <= 0) /* duplicate or reordered */
+ return 0;
- fval = scaled_div(s, rtt);
- fval = scaled_div32(fval, x_recv);
- p = tfrc_calc_x_reverse_lookup(fval);
+ if (SUB16(dccp_hdr(skb)->dccph_ccval, cur->li_ccval) > 4)
+ /*
+ * Implements RFC 4342, 10.2:
+ * If a packet S (skb) exists whose seqno comes `after' the one
+ * starting the current loss interval (cur) and if the modulo-16
+ * distance from C(cur) to C(S) is greater than 4, consider all
+ * subsequent packets as belonging to a new loss interval. This
+ * test is necessary since CCVal may wrap between intervals.
+ */
+ cur->li_is_closed = 1;
+
+ if (tfrc_lh_length(lh) == 1) /* due to RFC 3448, 6.3.1 */
+ return 0;
- dccp_pr_debug("%s(%p), receive rate=%u bytes/s, implied "
- "loss rate=%u\n", dccp_role(sk), sk, x_recv, p);
+ cur->li_length = length;
+ tfrc_lh_calc_i_mean(lh);
- if (p == 0)
- return ~0;
- else
- return 1000000 / p;
+ return (lh->i_mean < old_i_mean);
}
+EXPORT_SYMBOL_GPL(tfrc_lh_update_i_mean);
-void dccp_li_update_li(struct sock *sk,
- 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)
+/* Determine if `new_loss' does begin a new loss interval [RFC 4342, 10.2] */
+static inline u8 tfrc_lh_is_new_loss(struct tfrc_loss_interval *cur,
+ struct tfrc_rx_hist_entry *new_loss)
{
- struct dccp_li_hist_entry *head;
- u64 seq_temp;
-
- if (list_empty(li_hist_list)) {
- if (!dccp_li_hist_interval_new(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;
+ return dccp_delta_seqno(cur->li_seqno, new_loss->tfrchrx_seqno) > 0 &&
+ (cur->li_is_closed || SUB16(new_loss->tfrchrx_ccval, cur->li_ccval) > 4);
+}
- 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 */
+/** tfrc_lh_interval_add - Insert new record into the Loss Interval database
+ * @lh: Loss Interval database
+ * @rh: Receive history containing a fresh loss event
+ * @calc_first_li: Caller-dependent routine to compute length of first interval
+ * @sk: Used by @calc_first_li in caller-specific way (subtyping)
+ * Updates I_mean and returns 1 if a new interval has in fact been added to @lh.
+ */
+int tfrc_lh_interval_add(struct tfrc_loss_hist *lh, struct tfrc_rx_hist *rh,
+ u32 (*calc_first_li)(struct sock *), struct sock *sk)
+{
+ struct tfrc_loss_interval *cur = tfrc_lh_peek(lh), *new;
- /* new loss event detected */
- /* calculate last interval length */
- seq_temp = dccp_delta_seqno(head->dccplih_seqno, seq_loss);
- entry = dccp_li_hist_entry_new(GFP_ATOMIC);
+ if (cur != NULL && !tfrc_lh_is_new_loss(cur, tfrc_rx_hist_loss_prev(rh)))
+ return 0;
- if (entry == NULL) {
- DCCP_BUG("out of memory - can not allocate entry");
- return;
- }
+ new = tfrc_lh_demand_next(lh);
+ if (unlikely(new == NULL)) {
+ DCCP_CRIT("Cannot allocate/add loss record.");
+ return 0;
+ }
- list_add(&entry->dccplih_node, li_hist_list);
+ new->li_seqno = tfrc_rx_hist_loss_prev(rh)->tfrchrx_seqno;
+ new->li_ccval = tfrc_rx_hist_loss_prev(rh)->tfrchrx_ccval;
+ new->li_is_closed = 0;
- tail = li_hist_list->prev;
- list_del(tail);
- kmem_cache_free(dccp_li_cachep, tail);
+ if (++lh->counter == 1)
+ lh->i_mean = new->li_length = (*calc_first_li)(sk);
+ else {
+ cur->li_length = dccp_delta_seqno(cur->li_seqno, new->li_seqno);
+ new->li_length = dccp_delta_seqno(new->li_seqno,
+ tfrc_rx_hist_last_rcv(rh)->tfrchrx_seqno);
+ if (lh->counter > (2*LIH_SIZE))
+ lh->counter -= LIH_SIZE;
- /* Create the newest interval */
- entry->dccplih_seqno = seq_loss;
- entry->dccplih_interval = seq_temp;
- entry->dccplih_win_count = win_loss;
+ tfrc_lh_calc_i_mean(lh);
}
+ return 1;
}
+EXPORT_SYMBOL_GPL(tfrc_lh_interval_add);
-EXPORT_SYMBOL_GPL(dccp_li_update_li);
-
-static __init int dccp_li_init(void)
+int __init tfrc_li_init(void)
{
- dccp_li_cachep = kmem_cache_create("dccp_li_hist",
- sizeof(struct dccp_li_hist_entry),
- 0, SLAB_HWCACHE_ALIGN, NULL);
- return dccp_li_cachep == NULL ? -ENOBUFS : 0;
+ tfrc_lh_slab = kmem_cache_create("tfrc_li_hist",
+ sizeof(struct tfrc_loss_interval), 0,
+ SLAB_HWCACHE_ALIGN, NULL);
+ return tfrc_lh_slab == NULL ? -ENOBUFS : 0;
}
-static __exit void dccp_li_exit(void)
+void tfrc_li_exit(void)
{
- kmem_cache_destroy(dccp_li_cachep);
+ if (tfrc_lh_slab != NULL) {
+ kmem_cache_destroy(tfrc_lh_slab);
+ tfrc_lh_slab = NULL;
+ }
}
-
-module_init(dccp_li_init);
-module_exit(dccp_li_exit);
projects / linux-2.6-omap-h63xx.git / blobdiff