diff options
author | Gerrit Renker <gerrit@erg.abdn.ac.uk> | 2010-08-29 15:23:14 -0400 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2010-08-30 16:45:28 -0400 |
commit | 89858ad14307a398961a0f1414b04053c1475e4f (patch) | |
tree | 860eca4c0fb4c9c470d407407ba051ae814c9dfa /net/dccp/ccids/ccid3.c | |
parent | 4886fcad6e12572afbd230dfab1b268eace20d6d (diff) |
dccp ccid-3: use per-route RTO or TCP RTO as fallback
This makes RTAX_RTO_MIN also available to CCID-3, replacing the compile-time
RTO lower bound with a per-route tunable value.
The original Kconfig option solved the problem that a very low RTT (in the
order of HZ) can trigger too frequent and unnecessary reductions of the
sending rate.
This tunable does not affect the initial RTO value of 2 seconds specified in
RFC 5348, section 4.2 and Appendix B. But like the hardcoded Kconfig value,
it allows to adapt to network conditions.
The same effect as the original Kconfig option of 100ms is now achieved by
> ip route replace to unicast 192.168.0.0/24 rto_min 100j dev eth0
(assuming HZ=1000).
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/dccp/ccids/ccid3.c')
-rw-r--r-- | net/dccp/ccids/ccid3.c | 11 |
1 files changed, 5 insertions, 6 deletions
diff --git a/net/dccp/ccids/ccid3.c b/net/dccp/ccids/ccid3.c index 4340672a817c..278e17069322 100644 --- a/net/dccp/ccids/ccid3.c +++ b/net/dccp/ccids/ccid3.c | |||
@@ -460,13 +460,12 @@ done_computing_x: | |||
460 | sk->sk_write_space(sk); | 460 | sk->sk_write_space(sk); |
461 | 461 | ||
462 | /* | 462 | /* |
463 | * Update timeout interval for the nofeedback timer. | 463 | * Update timeout interval for the nofeedback timer. In order to control |
464 | * We use a configuration option to increase the lower bound. | 464 | * rate halving on networks with very low RTTs (<= 1 ms), use per-route |
465 | * This can help avoid triggering the nofeedback timer too | 465 | * tunable RTAX_RTO_MIN value as the lower bound. |
466 | * often ('spinning') on LANs with small RTTs. | ||
467 | */ | 466 | */ |
468 | hc->tx_t_rto = max_t(u32, 4 * hc->tx_rtt, (CONFIG_IP_DCCP_CCID3_RTO * | 467 | hc->tx_t_rto = max_t(u32, 4 * hc->tx_rtt, |
469 | (USEC_PER_SEC / 1000))); | 468 | USEC_PER_SEC/HZ * tcp_rto_min(sk)); |
470 | /* | 469 | /* |
471 | * Schedule no feedback timer to expire in | 470 | * Schedule no feedback timer to expire in |
472 | * max(t_RTO, 2 * s/X) = max(t_RTO, 2 * t_ipi) | 471 | * max(t_RTO, 2 * s/X) = max(t_RTO, 2 * t_ipi) |