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* tcp: consolidate congestion control undo functionsYuchung Cheng2017-08-061-10/+1
| | | | | | | | | | | Most TCP congestion controls are using identical logic to undo cwnd except BBR. This patch consolidates these similar functions to the one used currently by Reno and others. Suggested-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* tcp: add cwnd_undo functions to various tcp cc algorithmsFlorian Westphal2016-11-211-1/+10
| | | | | | | | | | | | | | | congestion control algorithms that do not halve cwnd in their .ssthresh should provide a .cwnd_undo rather than rely on current fallback which assumes reno halving (and thus doubles the cwnd). All of these do 'something else' in their .ssthresh implementation, thus store the cwnd on loss and provide .undo_cwnd to restore it again. A followup patch will remove the fallback and all algorithms will need to provide a .cwnd_undo function. Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: David S. Miller <davem@davemloft.net>
* tcp: add tcp_in_slow_start helperYuchung Cheng2015-07-091-1/+1
| | | | | | | | | | | | Add a helper to test the slow start condition in various congestion control modules and other places. This is to prepare a slight improvement in policy as to exactly when to slow start. Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Nandita Dukkipati <nanditad@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* tcp: whitespace fixesstephen hemminger2014-09-011-73/+72
| | | | | | | | Fix places where there is space before tab, long lines, and awkward if(){, double spacing etc. Add blank line after declaration/initialization. Signed-off-by: Stephen Hemminger <stephen@networkplumber.org> Signed-off-by: David S. Miller <davem@davemloft.net>
* tcp: remove in_flight parameter from cong_avoid() methodsEric Dumazet2014-05-031-2/+2
| | | | | | | | | | | | Commit e114a710aa505 ("tcp: fix cwnd limited checking to improve congestion control") obsoleted in_flight parameter from tcp_is_cwnd_limited() and its callers. This patch does the removal as promised. Signed-off-by: Eric Dumazet <edumazet@google.com> Acked-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* tcp: remove unused min_cwnd member of tcp_congestion_opsStanislav Fomichev2014-02-131-1/+0
| | | | | | | | | | Commit 684bad110757 "tcp: use PRR to reduce cwin in CWR state" removed all calls to min_cwnd, so we can safely remove it. Also, remove tcp_reno_min_cwnd because it was only used for min_cwnd. Signed-off-by: Stanislav Fomichev <stfomichev@yandex-team.ru> Acked-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* tcp: properly handle stretch acks in slow startYuchung Cheng2013-11-041-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | Slow start now increases cwnd by 1 if an ACK acknowledges some packets, regardless the number of packets. Consequently slow start performance is highly dependent on the degree of the stretch ACKs caused by receiver or network ACK compression mechanisms (e.g., delayed-ACK, GRO, etc). But slow start algorithm is to send twice the amount of packets of packets left so it should process a stretch ACK of degree N as if N ACKs of degree 1, then exits when cwnd exceeds ssthresh. A follow up patch will use the remainder of the N (if greater than 1) to adjust cwnd in the congestion avoidance phase. In addition this patch retires the experimental limited slow start (LSS) feature. LSS has multiple drawbacks but questionable benefit. The fractional cwnd increase in LSS requires a loop in slow start even though it's rarely used. Configuring such an increase step via a global sysctl on different BDPS seems hard. Finally and most importantly the slow start overshoot concern is now better covered by the Hybrid slow start (hystart) enabled by default. Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* tcp: mark tcp_congestion_ops read_mostlyStephen Hemminger2011-03-101-1/+1
| | | | | Signed-off-by: Stephen Hemminger <shemminger@vyatta.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* [TCP]: Cong.ctrl modules: remove unused good_ack from cong_avoidIlpo Järvinen2008-01-281-2/+1
| | | | | | Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
* [TCP]: remove unused argument to cong_avoid opStephen Hemminger2007-07-181-1/+1
| | | | | | | | | None of the existing TCP congestion controls use the rtt value pased in the ca_ops->cong_avoid interface. Which is lucky because seq_rtt could have been -1 when handling a duplicate ack. Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org> Signed-off-by: David S. Miller <davem@davemloft.net>
* [TCP] Highspeed: Limited slow-start is nowadays in tcp_slow_startIlpo Järvinen2007-05-031-21/+3
| | | | | | | | Reuse limited slow-start (RFC3742) included into tcp_cong instead of having another implementation in High Speed TCP. Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
* [NET] IPV4: Fix whitespace errors.YOSHIFUJI Hideaki2007-02-101-2/+2
| | | | | Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org> Signed-off-by: David S. Miller <davem@davemloft.net>
* [TCP] Congestion control (modulo lp, bic): use BUILD_BUG_ONAlexey Dobriyan2006-09-221-1/+1
| | | | | Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* [TCP] tcp_highspeed: Fix AI updates.Xiaoliang (David) Wei2006-07-121-4/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | I think there is still a problem with the AIMD parameter update in HighSpeed TCP code. Line 125~138 of the code (net/ipv4/tcp_highspeed.c): /* Update AIMD parameters */ if (tp->snd_cwnd > hstcp_aimd_vals[ca->ai].cwnd) { while (tp->snd_cwnd > hstcp_aimd_vals[ca->ai].cwnd && ca->ai < HSTCP_AIMD_MAX - 1) ca->ai++; } else if (tp->snd_cwnd < hstcp_aimd_vals[ca->ai].cwnd) { while (tp->snd_cwnd > hstcp_aimd_vals[ca->ai].cwnd && ca->ai > 0) ca->ai--; In fact, the second part (decreasing ca->ai) never decreases since the while loop's inequality is in the reverse direction. This leads to unfairness with multiple flows (once a flow happens to enjoy a higher ca->ai, it keeps enjoying that even its cwnd decreases) Here is a tentative fix (I also added a comment, trying to keep the change clear): Acked-by: Stephen Hemminger <shemminger@osdl.org> Signed-off-by: David S. Miller <davem@davemloft.net>
* Remove obsolete #include <linux/config.h>Jörn Engel2006-06-301-1/+0
| | | | | Signed-off-by: Jörn Engel <joern@wohnheim.fh-wedel.de> Signed-off-by: Adrian Bunk <bunk@stusta.de>
* [TCP]: Limited slow start for Highspeed TCPStephen Hemminger2006-06-171-3/+21
| | | | | | | | Implementation of RFC3742 limited slow start. Added as part of the TCP highspeed congestion control module. Signed-off-by: Stephen Hemminger <shemminger@osdl.org> Signed-off-by: David S. Miller <davem@davemloft.net>
* [TCP] tcp_highspeed: Fix problem observed by Xiaoliang (David) WeiStephen Hemminger2006-06-021-1/+2
| | | | | | | | | | | When snd_cwnd is smaller than 38 and the connection is in congestion avoidance phase (snd_cwnd > snd_ssthresh), the snd_cwnd seems to stop growing. The additive increase was confused because C array's are 0 based. Signed-off-by: Stephen Hemminger <shemminger@osdl.org> Signed-off-by: David S. Miller <davem@davemloft.net>
* [TCP]: Fix snd_cwnd adjustments in tcp_highspeed.cJohn Heffner2006-05-051-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | Xiaoliang (David) Wei wrote: > Hi gurus, > > I am reading the code of tcp_highspeed.c in the kernel and have a > question on the hstcp_cong_avoid function, specifically the following > AI part (line 136~143 in net/ipv4/tcp_highspeed.c ): > > /* Do additive increase */ > if (tp->snd_cwnd < tp->snd_cwnd_clamp) { > tp->snd_cwnd_cnt += ca->ai; > if (tp->snd_cwnd_cnt >= tp->snd_cwnd) { > tp->snd_cwnd++; > tp->snd_cwnd_cnt -= tp->snd_cwnd; > } > } > > In this part, when (tp->snd_cwnd_cnt == tp->snd_cwnd), > snd_cwnd_cnt will be -1... snd_cwnd_cnt is defined as u16, will this > small chance of getting -1 becomes a problem? > Shall we change it by reversing the order of the cwnd++ and cwnd_cnt -= > cwnd? Absolutely correct. Thanks. Signed-off-by: John Heffner <jheffner@psc.edu> Signed-off-by: David S. Miller <davem@davemloft.net>
* [TCP]: tcp_highspeed: fix AIMD table out-of-bounds accessPatrick McHardy2006-03-121-1/+1
| | | | | | | Covertiy #547 Signed-off-by: Patrick McHardy <kaber@trash.net> Signed-off-by: David S. Miller <davem@davemloft.net>
* [TCP]: TCP highspeed build errorStephen Hemminger2005-11-171-1/+1
| | | | | | | | There is a compile error that crept in with the last patch of TCP patches. Signed-off-by: Stephen Hemminger <shemminger@osdl.org> Signed-off-by: David S. Miller <davem@davemloft.net>
* [TCP]: add tcp_slow_start helperStephen Hemminger2005-11-101-4/+3
| | | | | | | | Move all the code that does linear TCP slowstart to one inline function to ease later patch to add ABC support. Signed-off-by: Stephen Hemminger <shemminger@osdl.org> Signed-off-by: David S. Miller <davem@davemloft.net>
* [TCP]: fix congestion window update when using TSO deferalStephen Hemminger2005-11-101-2/+2
| | | | | | | | | | | | | | | | | TCP peformance with TSO over networks with delay is awful. On a 100Mbit link with 150ms delay, we get 4Mbits/sec with TSO and 50Mbits/sec without TSO. The problem is with TSO, we intentionally do not keep the maximum number of packets in flight to fill the window, we hold out to until we can send a MSS chunk. But, we also don't update the congestion window unless we have filled, as per RFC2861. This patch replaces the check for the congestion window being full with something smarter that accounts for TSO. Signed-off-by: Stephen Hemminger <shemminger@osdl.org> Signed-off-by: David S. Miller <davem@davemloft.net>
* [ICSK]: Move TCP congestion avoidance members to icskArnaldo Carvalho de Melo2005-08-291-7/+10
| | | | | | | | | | | | | | | | | | | | | This changeset basically moves tcp_sk()->{ca_ops,ca_state,etc} to inet_csk(), minimal renaming/moving done in this changeset to ease review. Most of it is just changes of struct tcp_sock * to struct sock * parameters. With this we move to a state closer to two interesting goals: 1. Generalisation of net/ipv4/tcp_diag.c, becoming inet_diag.c, being used for any INET transport protocol that has struct inet_hashinfo and are derived from struct inet_connection_sock. Keeps the userspace API, that will just not display DCCP sockets, while newer versions of tools can support DCCP. 2. INET generic transport pluggable Congestion Avoidance infrastructure, using the current TCP CA infrastructure with DCCP. Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* [TCP]: Add High Speed TCP congestion control module.John Heffner2005-06-231-0/+181
Sally Floyd's high speed TCP congestion control. This is useful for comparison and research. Signed-off-by: John Heffner <jheffner@psc.edu> Signed-off-by: Stephen Hemminger <shemminger@osdl.org> Signed-off-by: David S. Miller <davem@davemloft.net>
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