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-rw-r--r--net/dccp/ccids/Kconfig20
-rw-r--r--net/dccp/ccids/ccid3.c27
2 files changed, 35 insertions, 12 deletions
diff --git a/net/dccp/ccids/Kconfig b/net/dccp/ccids/Kconfig
index dc973abe03b..fb168be2cb4 100644
--- a/net/dccp/ccids/Kconfig
+++ b/net/dccp/ccids/Kconfig
@@ -74,6 +74,26 @@ config IP_DCCP_CCID3_DEBUG
If in doubt, say N.
+choice
+ prompt "Select method for measuring the packet size s"
+ default IP_DCCP_CCID3_MEASURE_S_AS_MPS
+
+config IP_DCCP_CCID3_MEASURE_S_AS_MPS
+ bool "Always use MPS in place of s"
+ ---help---
+ This use is recommended as it is consistent with the initialisation
+ of X and suggested when s varies (rfc3448bis, (1) in section 4.1).
+config IP_DCCP_CCID3_MEASURE_S_AS_AVG
+ bool "Use moving average"
+ ---help---
+ An alternative way of tracking s, also supported by rfc3448bis.
+ This used to be the default for CCID-3 in previous kernels.
+config IP_DCCP_CCID3_MEASURE_S_AS_MAX
+ bool "Track the maximum payload length"
+ ---help---
+ An experimental method based on tracking the maximum packet size.
+endchoice
+
config IP_DCCP_CCID3_RTO
int "Use higher bound for nofeedback timer"
default 100
diff --git a/net/dccp/ccids/ccid3.c b/net/dccp/ccids/ccid3.c
index d654264c510..d77d3e664b7 100644
--- a/net/dccp/ccids/ccid3.c
+++ b/net/dccp/ccids/ccid3.c
@@ -136,17 +136,18 @@ static void ccid3_hc_tx_update_x(struct sock *sk, ktime_t *stamp)
}
/*
- * Track the mean packet size `s' (cf. RFC 4342, 5.3 and RFC 3448, 4.1)
- * @len: DCCP packet payload size in bytes
+ * ccid3_hc_tx_measure_packet_size - Measuring the packet size `s' (sec 4.1)
+ * @new_len: DCCP payload size in bytes (not used by all methods)
*/
-static inline void ccid3_hc_tx_update_s(struct ccid3_hc_tx_sock *hctx, int len)
+static u32 ccid3_hc_tx_measure_packet_size(struct sock *sk, const u16 new_len)
{
- const u16 old_s = hctx->s;
-
- hctx->s = tfrc_ewma(hctx->s, len, 9);
-
- if (hctx->s != old_s)
- ccid3_update_send_interval(hctx);
+#if defined(CONFIG_IP_DCCP_CCID3_MEASURE_S_AS_AVG)
+ return tfrc_ewma(ccid3_hc_tx_sk(sk)->s, new_len, 9);
+#elif defined(CONFIG_IP_DCCP_CCID3_MEASURE_S_AS_MAX)
+ return max(ccid3_hc_tx_sk(sk)->s, new_len);
+#else /* CONFIG_IP_DCCP_CCID3_MEASURE_S_AS_MPS */
+ return dccp_sk(sk)->dccps_mss_cache;
+#endif
}
/*
@@ -271,8 +272,6 @@ static int ccid3_hc_tx_send_packet(struct sock *sk, struct sk_buff *skb)
/* Set t_0 for initial packet */
hctx->t_nom = now;
- hctx->s = skb->len;
-
/*
* Use initial RTT sample when available: recommended by erratum
* to RFC 4342. This implements the initialisation procedure of
@@ -294,6 +293,9 @@ static int ccid3_hc_tx_send_packet(struct sock *sk, struct sk_buff *skb)
hctx->x = dp->dccps_mss_cache;
hctx->x <<= 6;
}
+
+ /* Compute t_ipi = s / X */
+ hctx->s = ccid3_hc_tx_measure_packet_size(sk, skb->len);
ccid3_update_send_interval(hctx);
} else {
@@ -326,7 +328,8 @@ static void ccid3_hc_tx_packet_sent(struct sock *sk, unsigned int len)
{
struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
- ccid3_hc_tx_update_s(hctx, len);
+ /* Changes to s will become effective the next time X is computed */
+ hctx->s = ccid3_hc_tx_measure_packet_size(sk, len);
if (tfrc_tx_hist_add(&hctx->hist, dccp_sk(sk)->dccps_gss))
DCCP_CRIT("packet history - out of memory!");