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2015-07-09tcp: add tcp_in_slow_start helperYuchung Cheng
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>
2014-09-01tcp: whitespace fixesstephen hemminger
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>
2014-05-03tcp: remove in_flight parameter from cong_avoid() methodsEric Dumazet
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>
2013-11-04tcp: properly handle stretch acks in slow startYuchung Cheng
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>
2011-03-10tcp: mark tcp_congestion_ops read_mostlyStephen Hemminger
Signed-off-by: Stephen Hemminger <shemminger@vyatta.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2009-11-23net/ipv4: Move && and || to end of previous lineJoe Perches
On Sun, 2009-11-22 at 16:31 -0800, David Miller wrote: > It should be of the form: > if (x && > y) > > or: > if (x && y) > > Fix patches, rather than complaints, for existing cases where things > do not follow this pattern are certainly welcome. Also collapsed some multiple tabs to single space. Signed-off-by: Joe Perches <joe@perches.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2009-03-02htcp: merge icsk_ca_state compareIlpo Järvinen
Similar to what is done elsewhere in TCP code when double state checks are being done. Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-11-12tcp_htcp: last_cong bug fixDoug Leith
This patch fixes a minor bug in tcp_htcp.c which has been highlighted by Lachlan Andrew and Lawrence Stewart. Currently, the time since the last congestion event, which is stored in variable last_cong, is reset whenever there is a state change into TCP_CA_Open. This includes transitions of the type TCP_CA_Open->TCP_CA_Disorder->TCP_CA_Open which are not associated with backoff of cwnd. The patch changes last_cong to be updated only on transitions into TCP_CA_Open that occur after experiencing the congestion-related states TCP_CA_Loss, TCP_CA_Recovery, TCP_CA_CWR. Signed-off-by: Doug Leith <doug.leith@nuim.ie> Signed-off-by: David S. Miller <davem@davemloft.net>
2008-01-28[TCP]: Cong.ctrl modules: remove unused good_ack from cong_avoidIlpo Järvinen
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>
2007-08-07[TCP]: H-TCP maxRTT estimation at startupStephen Hemminger
Small patch to H-TCP from Douglas Leith. Fix estimation of maxRTT. The original code ignores rtt measurements during slow start (via the check tp->snd_ssthresh < 0xFFFF) yet this is probably a good time to try to estimate max rtt as delayed acking is disabled and slow start will only exit on a loss which presumably corresponds to a maxrtt measurement. Second, the original code (via the check htcp_ccount(ca) > 3) ignores rtt data during what it estimates to be the first 3 round-trip times. This seems like an unnecessary check now that the RCV timestamp are no longer used for rtt estimation. Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2007-07-31[TCP]: htcp - use measured rttStephen Hemminger
Change HTCP to use measured RTT rather than smooth RTT. Srtt is computed using the TCP receive timestamp options, so it is vulnerable to hostile receivers. To avoid any problems this might cause use the measured RTT instead. Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2007-07-31[TCP]: congestion control API pass RTT in microsecondsStephen Hemminger
This patch changes the API for the callback that is done after an ACK is received. It solves a couple of issues: * Some congestion controls want higher resolution value of RTT (controlled by TCP_CONG_RTT_SAMPLE flag). These don't really want a ktime, but all compute a RTT in microseconds. * Other congestion control could use RTT at jiffies resolution. To keep API consistent the units should be the same for both cases, just the resolution should change. Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2007-07-19missed cong_avoid() instanceAl Viro
Removal of rtt argument in ->cong_avoid() had missed tcp_htcp.c instance. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-18[TCP]: remove unused argument to cong_avoid opStephen Hemminger
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>
2007-04-25[TCP]: Congestion control API update.Stephen Hemminger
Do some simple changes to make congestion control API faster/cleaner. * use ktime_t rather than timeval * merge rtt sampling into existing ack callback this means one indirect call versus two per ack. * use flags bits to store options/settings Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2007-02-12[TCP]: cleanup of htcp (resend)Stephen Hemminger
Minor non-invasive cleanups: * white space around operators and line wrapping * use const * use __read_mostly Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2007-02-10[NET] IPV4: Fix whitespace errors.YOSHIFUJI Hideaki
Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2006-12-02[TCP] htcp: Better packing of struct htcp.David S. Miller
Based upon a patch by Joe Perches. Signed-off-by: David S. Miller <davem@davemloft.net>
2006-10-25[TCP] H-TCP: fix integer overflowGavin McCullagh
When using H-TCP with a single flow on a 500Mbit connection (or less actually), alpha can exceed 65000, so alpha needs to be a u32. Signed-off-by: Gavin McCullagh <gavin.mccullagh@nuim.ie> Signed-off-by: Doug Leith <doug.leith@nuim.ie> Signed-off-by: David S. Miller <davem@davemloft.net>
2006-09-22[TCP] Congestion control (modulo lp, bic): use BUILD_BUG_ONAlexey Dobriyan
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2006-06-30Remove obsolete #include <linux/config.h>Jörn Engel
Signed-off-by: Jörn Engel <joern@wohnheim.fh-wedel.de> Signed-off-by: Adrian Bunk <bunk@stusta.de>
2006-06-17[TCP]: Minimum congestion window consolidation.Stephen Hemminger
Many of the TCP congestion methods all just use ssthresh as the minimum congestion window on decrease. Rather than duplicating the code, just have that be the default if that handle in the ops structure is not set. Minor behaviour change to TCP compound. It probably wants to use this (ssthresh) as lower bound, rather than ssthresh/2 because the latter causes undershoot on loss. Signed-off-by: Stephen Hemminger <shemminger@osdl.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2006-03-20[TCP] H-TCP: Better time accountingBaruch Even
Instead of estimating the time since the last congestion event, count it directly. Signed-off-by: Baruch Even <baruch@ev-en.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2006-03-20[TCP] H-TCP: Account for delayed-ACKsBaruch Even
Account for delayed-ACKs in H-TCP. Delayed-ACKs cause H-TCP to be less aggressive than its design calls for. It is especially true when the receiver is a Linux machine where the average delayed ack is over 3 packets with values of 7 not unheard of. Signed-off-By: Baruch Even <baruch@ev-en.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2006-03-20[TCP] H-TCP: Use msecs_to_jiffiesBaruch Even
Use functions to calculate jiffies from milliseconds and not the old, crude method of dividing HZ by a value. Ensures more accurate values even in the face of strange HZ values. Signed-off-By: Baruch Even <baruch@ev-en.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2006-01-30[TCP] H-TCP: Fix accountingBaruch Even
This fixes the accounting in H-TCP, the ccount variable is also adjusted a few lines above this one. This line was not supposed to be there and wasn't there in the patches originally submitted, the four patches submitted were merged to one and in that merge the bug was introduced. Signed-Off-By: Baruch Even <baruch@ev-en.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2005-11-10[TCP]: add tcp_slow_start helperStephen Hemminger
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>
2005-11-10[TCP]: fix congestion window update when using TSO deferalStephen Hemminger
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>
2005-08-29[ICSK]: Move TCP congestion avoidance members to icskArnaldo Carvalho de Melo
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>
2005-06-23[TCP]: Add H-TCP congestion control module.Baruch Even
H-TCP is a congestion control algorithm developed at the Hamilton Institute, by Douglas Leith and Robert Shorten. It is extending the standard Reno algorithm with mode switching is thus a relatively simple modification. H-TCP is defined in a layered manner as it is still a research platform. The basic form includes the modification of beta according to the ratio of maxRTT to min RTT and the alpha=2*factor*(1-beta) relation, where factor is dependant on the time since last congestion. The other layers improve convergence by adding appropriate factors to alpha. The following patch implements the H-TCP algorithm in it's basic form. Signed-Off-By: Baruch Even <baruch@ev-en.org> Signed-off-by: David S. Miller <davem@davemloft.net>