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authorArnaldo Carvalho de Melo <acme@redhat.com>2007-06-14 17:41:28 -0300
committerDavid S. Miller <davem@sunset.davemloft.net>2007-07-10 22:15:20 -0700
commitcc0a910b942d11069d35f52b2c0ed0e229e2fb46 (patch)
tree9d378b79a25b7c5f03ce9f713f00648781953dbd /net/dccp/ccids/lib/loss_interval.c
parent878ac60023c4ba11a7fbf0b1dfe07b8472c0d6ce (diff)
[DCCP] loss_interval: Move ccid3_hc_rx_update_li to loss_interval
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>
Diffstat (limited to 'net/dccp/ccids/lib/loss_interval.c')
-rw-r--r--net/dccp/ccids/lib/loss_interval.c160
1 files changed, 160 insertions, 0 deletions
diff --git a/net/dccp/ccids/lib/loss_interval.c b/net/dccp/ccids/lib/loss_interval.c
index 3829afc3117..ee59fde6653 100644
--- a/net/dccp/ccids/lib/loss_interval.c
+++ b/net/dccp/ccids/lib/loss_interval.c
@@ -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)
{
@@ -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);