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| author | Gerrit Renker <gerrit@erg.abdn.ac.uk> | 2007-03-20 15:12:10 -0300 |
|---|---|---|
| committer | David S. Miller <davem@sunset.davemloft.net> | 2007-04-25 22:26:58 -0700 |
| commit | a21f9f96cd035b0d9aec32d80ea0152672fbed42 (patch) | |
| tree | fa868d6bc48b46eae10ed864e74bb9f790579dfc /net/dccp | |
| parent | 1761f7d7fea32c2290710f5c0afa0c3d93220593 (diff) | |
| download | op-kernel-dev-a21f9f96cd035b0d9aec32d80ea0152672fbed42.zip op-kernel-dev-a21f9f96cd035b0d9aec32d80ea0152672fbed42.tar.gz | |
[CCID3]: Wrap computation of RFC3390-initial rate into separate function
The CCID 3 and TFRC specs (RFC 4342, RFC 3448, draft-3448bis) make frequent
reference to the computation of the RFC-3390 initial sending rate:
1. Initial sending rate when RTT is known (RFC 4342, p. 6)
2. Response to Idle/Application-Limited periods (RFC 4342, 5.1)
This warrants putting the code into its own function, for later code reuse.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/dccp')
| -rw-r--r-- | net/dccp/ccids/ccid3.c | 25 |
1 files changed, 18 insertions, 7 deletions
diff --git a/net/dccp/ccids/ccid3.c b/net/dccp/ccids/ccid3.c index dc6e418..8d33a09 100644 --- a/net/dccp/ccids/ccid3.c +++ b/net/dccp/ccids/ccid3.c @@ -82,6 +82,21 @@ static void ccid3_hc_tx_set_state(struct sock *sk, } /* + * Compute the initial sending rate X_init according to RFC 3390: + * w_init = min(4 * MSS, max(2 * MSS, 4380 bytes)) + * X_init = w_init / RTT + * For consistency with other parts of the code, X_init is scaled by 2^6. + */ +static inline u64 rfc3390_initial_rate(struct sock *sk) +{ + const struct dccp_sock *dp = dccp_sk(sk); + const __u32 w_init = min(4 * dp->dccps_mss_cache, + max(2 * dp->dccps_mss_cache, 4380U)); + + return scaled_div(w_init << 6, ccid3_hc_tx_sk(sk)->ccid3hctx_rtt); +} + +/* * Recalculate t_ipi and delta (should be called whenever X changes) */ static inline void ccid3_update_send_interval(struct ccid3_hc_tx_sock *hctx) @@ -469,20 +484,16 @@ static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb) /* * Larger Initial Windows [RFC 4342, sec. 5] */ - __u32 w_init = min(4 * dp->dccps_mss_cache, - max(2 * dp->dccps_mss_cache, 4380U)); hctx->ccid3hctx_rtt = r_sample; - hctx->ccid3hctx_x = scaled_div(w_init << 6, r_sample); + hctx->ccid3hctx_x = rfc3390_initial_rate(sk); hctx->ccid3hctx_t_ld = now; ccid3_update_send_interval(hctx); - ccid3_pr_debug("%s(%p), s=%u, MSS=%u, w_init=%u, " + ccid3_pr_debug("%s(%p), s=%u, MSS=%u, " "R_sample=%dus, X=%u\n", dccp_role(sk), sk, hctx->ccid3hctx_s, - dp->dccps_mss_cache, - w_init, - (int)r_sample, + dp->dccps_mss_cache, (int)r_sample, (unsigned)(hctx->ccid3hctx_x >> 6)); ccid3_hc_tx_set_state(sk, TFRC_SSTATE_FBACK); |
