/*
* net/dccp/ccids/ccid3.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>
*
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
-#include "../ccid.h"
#include "../dccp.h"
-#include "lib/packet_history.h"
-#include "lib/loss_interval.h"
-#include "lib/tfrc.h"
#include "ccid3.h"
#include <asm/unaligned.h>
return 0;
}
+/** ccid3_first_li - Implements [RFC 3448, 6.3.1]
+ *
+ * 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 (scaled).
+ */
+static u32 ccid3_first_li(struct sock *sk)
+{
+ struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
+ u32 x_recv, p, delta;
+ u64 fval;
+
+ if (hcrx->ccid3hcrx_rtt == 0) {
+ DCCP_WARN("No RTT estimate available, using fallback RTT\n");
+ hcrx->ccid3hcrx_rtt = DCCP_FALLBACK_RTT;
+ }
+
+ delta = ktime_to_us(net_timedelta(hcrx->ccid3hcrx_tstamp_last_feedback));
+ x_recv = scaled_div32(hcrx->ccid3hcrx_bytes_recv, delta);
+ if (x_recv == 0) { /* would also trigger divide-by-zero */
+ DCCP_WARN("X_recv==0\n");
+ if ((x_recv = hcrx->ccid3hcrx_x_recv) == 0) {
+ DCCP_BUG("stored value of X_recv is zero");
+ return ~0U;
+ }
+ }
+
+ fval = scaled_div(hcrx->ccid3hcrx_s, hcrx->ccid3hcrx_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);
+
+ return p == 0 ? ~0U : scaled_div(1, p);
+}
+
static void ccid3_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb)
{
struct ccid3_hc_rx_sock *hcrx = ccid3_hc_rx_sk(sk);
/*
* Handle pending losses and otherwise check for new loss
*/
+ if (tfrc_rx_hist_loss_pending(&hcrx->ccid3hcrx_hist) &&
+ tfrc_rx_handle_loss(&hcrx->ccid3hcrx_hist,
+ &hcrx->ccid3hcrx_li_hist,
+ skb, ndp, ccid3_first_li, sk) ) {
+ do_feedback = CCID3_FBACK_PARAM_CHANGE;
+ goto done_receiving;
+ }
+
if (tfrc_rx_hist_new_loss_indicated(&hcrx->ccid3hcrx_hist, skb, ndp))
goto update_records;
if (unlikely(!is_data_packet))
goto update_records;
- if (list_empty(&hcrx->ccid3hcrx_li_hist)) { /* no loss so far: p = 0 */
+ if (!tfrc_lh_is_initialised(&hcrx->ccid3hcrx_li_hist)) {
const u32 sample = tfrc_rx_hist_sample_rtt(&hcrx->ccid3hcrx_hist, skb);
/*
* Empty loss history: no loss so far, hence p stays 0.
*/
if (sample != 0)
hcrx->ccid3hcrx_rtt = tfrc_ewma(hcrx->ccid3hcrx_rtt, sample, 9);
+
+ } else if (tfrc_lh_update_i_mean(&hcrx->ccid3hcrx_li_hist, skb)) {
+ /*
+ * Step (3) of [RFC 3448, 6.1]: Recompute I_mean and, if I_mean
+ * has decreased (resp. p has increased), send feedback now.
+ */
+ do_feedback = CCID3_FBACK_PARAM_CHANGE;
}
/*
update_records:
tfrc_rx_hist_add_packet(&hcrx->ccid3hcrx_hist, skb, ndp);
+done_receiving:
if (do_feedback)
ccid3_hc_rx_send_feedback(sk, skb, do_feedback);
}
{
struct ccid3_hc_rx_sock *hcrx = ccid_priv(ccid);
- ccid3_pr_debug("entry\n");
-
hcrx->ccid3hcrx_state = TFRC_RSTATE_NO_DATA;
- INIT_LIST_HEAD(&hcrx->ccid3hcrx_li_hist);
+ tfrc_lh_init(&hcrx->ccid3hcrx_li_hist);
return tfrc_rx_hist_alloc(&hcrx->ccid3hcrx_hist);
}
ccid3_hc_rx_set_state(sk, TFRC_RSTATE_TERM);
- /* Empty packet history */
tfrc_rx_hist_purge(&hcrx->ccid3hcrx_hist);
-
- /* Empty loss interval history */
- dccp_li_hist_purge(&hcrx->ccid3hcrx_li_hist);
+ tfrc_lh_cleanup(&hcrx->ccid3hcrx_li_hist);
}
static void ccid3_hc_rx_get_info(struct sock *sk, struct tcp_info *info)
#include <linux/list.h>
#include <linux/types.h>
#include <linux/tfrc.h>
-#include "lib/packet_history.h"
+#include "lib/tfrc.h"
#include "../ccid.h"
/* Two seconds as per RFC 3448 4.2 */
* @ccid3hcrx_bytes_recv - Total sum of DCCP payload bytes
* @ccid3hcrx_tstamp_last_feedback - Time at which last feedback was sent
* @ccid3hcrx_tstamp_last_ack - Time at which last feedback was sent
- * @ccid3hcrx_hist - Packet history
- * @ccid3hcrx_li_hist - Loss Interval History
+ * @ccid3hcrx_hist - Packet history (loss detection + RTT sampling)
+ * @ccid3hcrx_li_hist - Loss Interval database
* @ccid3hcrx_s - Received packet size in bytes
* @ccid3hcrx_pinv - Inverse of Loss Event Rate (RFC 4342, sec. 8.5)
*/
u32 ccid3hcrx_bytes_recv;
ktime_t ccid3hcrx_tstamp_last_feedback;
struct tfrc_rx_hist ccid3hcrx_hist;
- struct list_head ccid3hcrx_li_hist;
+ struct tfrc_loss_hist ccid3hcrx_li_hist;
u16 ccid3hcrx_s;
- u32 ccid3hcrx_pinv;
+#define ccid3hcrx_pinv ccid3hcrx_li_hist.i_mean
};
static inline struct ccid3_hc_rx_sock *ccid3_hc_rx_sk(const struct sock *sk)
}
EXPORT_SYMBOL_GPL(tfrc_lh_interval_add);
-int __init 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;
}
-void dccp_li_exit(void)
+void tfrc_li_exit(void)
{
- if (dccp_li_cachep != NULL) {
- kmem_cache_destroy(dccp_li_cachep);
- dccp_li_cachep = NULL;
+ if (tfrc_lh_slab != NULL) {
+ kmem_cache_destroy(tfrc_lh_slab);
+ tfrc_lh_slab = NULL;
}
}
projects / linux-2.6 / commitdiff