aboutsummaryrefslogtreecommitdiffstats
path: root/net
diff options
context:
space:
mode:
authorGerrit Renker <gerrit@erg.abdn.ac.uk>2006-12-09 21:00:14 -0500
committerDavid S. Miller <davem@sunset.davemloft.net>2006-12-11 17:34:40 -0500
commitff58629824c068e2a75402b5b83f12af0b36d394 (patch)
tree0d8f4a64dbe4e52879cac33174df406adf77da44 /net
parent45393a66a2c30fc8ed86e6c79a63a3cd5231c69f (diff)
[DCCP] ccid3: Two optimisations for sending rate recomputation
This performs two optimisations for the recomputation of the sending rate. 1) Currently the target sending rate X_calc is recalculated whenever a) the nofeedback timer expires, or b) a feedback packet is received. In the (a) case, recomputing X_calc is redundant, since * the parameters p and RTT do not change in between the reception of feedback packets; * the parameter X_recv is either modified from received feedback or via the nofeedback timer; * a test (`p == 0') in the nofeedback timer avoids using a stale/undefined value of X_calc if p was previously 0. 2) The nofeedback timer now only recomputes a timestamp when p == 0. This is according to step (4) of [RFC 3448, 4.3] and avoids unnecessarily determining a timestamp. A debug statement about not updating X is also removed - it helps very little in debugging and just clutters the logs. Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk> Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz> Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
Diffstat (limited to 'net')
-rw-r--r--net/dccp/ccids/ccid3.c27
1 files changed, 16 insertions, 11 deletions
diff --git a/net/dccp/ccids/ccid3.c b/net/dccp/ccids/ccid3.c
index f1b745ee9cb6..92e893ee77c2 100644
--- a/net/dccp/ccids/ccid3.c
+++ b/net/dccp/ccids/ccid3.c
@@ -138,9 +138,6 @@ static void ccid3_hc_tx_update_x(struct sock *sk, struct timeval *now)
138 const __u32 old_x = hctx->ccid3hctx_x; 138 const __u32 old_x = hctx->ccid3hctx_x;
139 139
140 if (hctx->ccid3hctx_p > 0) { 140 if (hctx->ccid3hctx_p > 0) {
141 hctx->ccid3hctx_x_calc = tfrc_calc_x(hctx->ccid3hctx_s,
142 hctx->ccid3hctx_rtt,
143 hctx->ccid3hctx_p);
144 hctx->ccid3hctx_x = max_t(u32, min(hctx->ccid3hctx_x_calc, 141 hctx->ccid3hctx_x = max_t(u32, min(hctx->ccid3hctx_x_calc,
145 hctx->ccid3hctx_x_recv * 2), 142 hctx->ccid3hctx_x_recv * 2),
146 hctx->ccid3hctx_s / TFRC_T_MBI); 143 hctx->ccid3hctx_s / TFRC_T_MBI);
@@ -152,8 +149,7 @@ static void ccid3_hc_tx_update_x(struct sock *sk, struct timeval *now)
152 usecs_div(hctx->ccid3hctx_s, 149 usecs_div(hctx->ccid3hctx_s,
153 hctx->ccid3hctx_rtt) ); 150 hctx->ccid3hctx_rtt) );
154 hctx->ccid3hctx_t_ld = *now; 151 hctx->ccid3hctx_t_ld = *now;
155 } else 152 }
156 ccid3_pr_debug("Not changing X\n");
157 153
158 if (hctx->ccid3hctx_x != old_x) 154 if (hctx->ccid3hctx_x != old_x)
159 ccid3_update_send_time(hctx); 155 ccid3_update_send_time(hctx);
@@ -223,9 +219,11 @@ static void ccid3_hc_tx_no_feedback_timer(unsigned long data)
223 ccid3_pr_debug("%s, sk=%p, state=%s, not idle\n", 219 ccid3_pr_debug("%s, sk=%p, state=%s, not idle\n",
224 dccp_role(sk), sk, 220 dccp_role(sk), sk,
225 ccid3_tx_state_name(hctx->ccid3hctx_state)); 221 ccid3_tx_state_name(hctx->ccid3hctx_state));
226 /* Halve sending rate */
227 222
228 /* If (p == 0 || X_calc > 2 * X_recv) 223 /*
224 * Modify the cached value of X_recv [RFC 3448, 4.4]
225 *
226 * If (p == 0 || X_calc > 2 * X_recv)
229 * X_recv = max(X_recv / 2, s / (2 * t_mbi)); 227 * X_recv = max(X_recv / 2, s / (2 * t_mbi));
230 * Else 228 * Else
231 * X_recv = X_calc / 4; 229 * X_recv = X_calc / 4;
@@ -233,14 +231,15 @@ static void ccid3_hc_tx_no_feedback_timer(unsigned long data)
233 BUG_ON(hctx->ccid3hctx_p && !hctx->ccid3hctx_x_calc); 231 BUG_ON(hctx->ccid3hctx_p && !hctx->ccid3hctx_x_calc);
234 232
235 if (hctx->ccid3hctx_p == 0 || 233 if (hctx->ccid3hctx_p == 0 ||
236 hctx->ccid3hctx_x_calc > 2 * hctx->ccid3hctx_x_recv) 234 hctx->ccid3hctx_x_calc > 2 * hctx->ccid3hctx_x_recv) {
237 hctx->ccid3hctx_x_recv = max_t(u32, hctx->ccid3hctx_x_recv / 2, 235 hctx->ccid3hctx_x_recv = max_t(u32, hctx->ccid3hctx_x_recv / 2,
238 hctx->ccid3hctx_s / (2 * TFRC_T_MBI)); 236 hctx->ccid3hctx_s / (2 * TFRC_T_MBI));
239 else 237 if (hctx->ccid3hctx_p == 0)
238 dccp_timestamp(sk, &now);
239 } else
240 hctx->ccid3hctx_x_recv = hctx->ccid3hctx_x_calc / 4; 240 hctx->ccid3hctx_x_recv = hctx->ccid3hctx_x_calc / 4;
241 241
242 /* Update sending rate */ 242 /* Now recalculate X [RFC 3448, 4.3, step (4)] */
243 dccp_timestamp(sk, &now);
244 ccid3_hc_tx_update_x(sk, &now); 243 ccid3_hc_tx_update_x(sk, &now);
245 } 244 }
246 /* 245 /*
@@ -496,6 +495,12 @@ static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
496 hctx->ccid3hctx_rtt = (9 * hctx->ccid3hctx_rtt + 495 hctx->ccid3hctx_rtt = (9 * hctx->ccid3hctx_rtt +
497 (u32)r_sample ) / 10; 496 (u32)r_sample ) / 10;
498 497
498 /* Update sending rate (step 4 of [RFC 3448, 4.3]) */
499 if (hctx->ccid3hctx_p > 0)
500 hctx->ccid3hctx_x_calc =
501 tfrc_calc_x(hctx->ccid3hctx_s,
502 hctx->ccid3hctx_rtt,
503 hctx->ccid3hctx_p);
499 ccid3_hc_tx_update_x(sk, &now); 504 ccid3_hc_tx_update_x(sk, &now);
500 505
501 ccid3_pr_debug("%s(%p), RTT=%uus (sample=%ldus), s=%u, " 506 ccid3_pr_debug("%s(%p), RTT=%uus (sample=%ldus), s=%u, "