30 May, 2018
1 commit
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[ Upstream commit ecc832758a654e375924ebf06a4ac971acb5ce60 ]
The link to the pdf containing the algorithm description is now a
dead link; it seems http://www.ifp.illinois.edu/~srikant/ has been
moved to https://sites.google.com/a/illinois.edu/srikant/ and none of
the original papers can be found there...I have replaced it with the only working copy I was able to find.
n.b. there is also a copy available at:
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.296.6350&rep=rep1&type=pdf
However, this seems to only be a *cached* version, so I am unsure
exactly how reliable that link can be expected to remain over time
and have decided against using that one.Signed-off-by: Joey Pabalinas
net/ipv4/tcp_illinois.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)Signed-off-by: David S. Miller
Signed-off-by: Sasha Levin
Signed-off-by: Greg Kroah-Hartman
07 Aug, 2017
1 commit
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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
Signed-off-by: Yuchung Cheng
Signed-off-by: Neal Cardwell
Signed-off-by: David S. Miller
22 Nov, 2016
1 commit
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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
Signed-off-by: David S. Miller
12 May, 2016
1 commit
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Replace 2 arguments (cnt and rtt) in the congestion control modules'
pkts_acked() function with a struct. This will allow adding more
information without having to modify existing congestion control
modules (tcp_nv in particular needs bytes in flight when packet
was sent).As proposed by Neal Cardwell in his comments to the tcp_nv patch.
Signed-off-by: Lawrence Brakmo
Acked-by: Yuchung Cheng
Signed-off-by: David S. Miller
10 Jul, 2015
1 commit
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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
Signed-off-by: Neal Cardwell
Signed-off-by: Eric Dumazet
Signed-off-by: Nandita Dukkipati
Signed-off-by: David S. Miller
30 Apr, 2015
1 commit
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We would like that optional info provided by Congestion Control
modules using netlink can also be read using getsockopt()This patch changes get_info() to put this information in a buffer,
instead of skb, like tcp_get_info(), so that following patch
can reuse this common infrastructure.Signed-off-by: Eric Dumazet
Cc: Yuchung Cheng
Cc: Neal Cardwell
Acked-by: Neal Cardwell
Acked-by: Daniel Borkmann
Acked-by: Yuchung Cheng
Signed-off-by: David S. Miller
18 Apr, 2015
1 commit
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Two different problems are fixed here :
1) inet_sk_diag_fill() might be called without socket lock held.
icsk->icsk_ca_ops can change under us and module be unloaded.
-> Access to freed memory.
Fix this using rcu_read_lock() to prevent module unload.2) Some TCP Congestion Control modules provide information
but again this is not safe against icsk->icsk_ca_ops
change and nla_put() errors were ignored. Some sockets
could not get the additional info if skb was almost full.Fix this by returning a status from get_info() handlers and
using rcu protection as well.Signed-off-by: Eric Dumazet
Acked-by: Daniel Borkmann
Signed-off-by: David S. Miller
02 Sep, 2014
1 commit
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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
Signed-off-by: David S. Miller
04 May, 2014
1 commit
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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
Acked-by: Neal Cardwell
Signed-off-by: David S. Miller
27 Feb, 2014
1 commit
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Upcoming congestion controls for TCP require usec resolution for RTT
estimations. Millisecond resolution is simply not enough these days.FQ/pacing in DC environments also require this change for finer control
and removal of bimodal behavior due to the current hack in
tcp_update_pacing_rate() for 'small rtt'TCP_CONG_RTT_STAMP is no longer needed.
As Julian Anastasov pointed out, we need to keep user compatibility :
tcp_metrics used to export RTT and RTTVAR in msec resolution,
so we added RTT_US and RTTVAR_US. An iproute2 patch is needed
to use the new attributes if provided by the kernel.In this example ss command displays a srtt of 32 usecs (10Gbit link)
lpk51:~# ./ss -i dst lpk52
Netid State Recv-Q Send-Q Local Address:Port Peer
Address:Port
tcp ESTAB 0 1 10.246.11.51:42959
10.246.11.52:64614
cubic wscale:6,6 rto:201 rtt:0.032/0.001 ato:40 mss:1448
cwnd:10 send
3620.0Mbps pacing_rate 7240.0Mbps unacked:1 rcv_rtt:993 rcv_space:29559Updated iproute2 ip command displays :
lpk51:~# ./ip tcp_metrics | grep 10.246.11.52
10.246.11.52 age 561.914sec cwnd 10 rtt 274us rttvar 213us source
10.246.11.51Old binary displays :
lpk51:~# ip tcp_metrics | grep 10.246.11.52
10.246.11.52 age 561.914sec cwnd 10 rtt 250us rttvar 125us source
10.246.11.51With help from Julian Anastasov, Stephen Hemminger and Yuchung Cheng
Signed-off-by: Eric Dumazet
Acked-by: Neal Cardwell
Cc: Stephen Hemminger
Cc: Yuchung Cheng
Cc: Larry Brakmo
Cc: Julian Anastasov
Signed-off-by: David S. Miller
14 Feb, 2014
1 commit
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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
Acked-by: Yuchung Cheng
Signed-off-by: David S. Miller
24 Jan, 2014
2 commits
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Now that the definition is centralized in , the
definitions of U32_MAX (and related) elsewhere in the kernel can be
removed.Signed-off-by: Alex Elder
Acked-by: Sage Weil
Acked-by: David S. Miller
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
The symbol U32_MAX is defined in several spots. Change these
definitions to be conditional. This is in preparation for the next
patch, which centralizes the definition in .Signed-off-by: Alex Elder
Cc: Sage Weil
Cc: David Miller
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
05 Nov, 2013
1 commit
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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
Signed-off-by: Neal Cardwell
Signed-off-by: Eric Dumazet
Signed-off-by: David S. Miller
01 Nov, 2012
1 commit
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Reading TCP stats when using TCP Illinois congestion control algorithm
can cause a divide by zero kernel oops.The division by zero occur in tcp_illinois_info() at:
do_div(t, ca->cnt_rtt);
where ca->cnt_rtt can become zero (when rtt_reset is called)Steps to Reproduce:
1. Register tcp_illinois:
# sysctl -w net.ipv4.tcp_congestion_control=illinois
2. Monitor internal TCP information via command "ss -i"
# watch -d ss -i
3. Establish new TCP conn to machineEither it fails at the initial conn, or else it needs to wait
for a loss or a reset.This is only related to reading stats. The function avg_delay() also
performs the same divide, but is guarded with a (ca->cnt_rtt > 0) at its
calling point in update_params(). Thus, simply fix tcp_illinois_info().Function tcp_illinois_info() / get_info() is called without
socket lock. Thus, eliminate any race condition on ca->cnt_rtt
by using a local stack variable. Simply reuse info.tcpv_rttcnt,
as its already set to ca->cnt_rtt.
Function avg_delay() is not affected by this race condition, as
its called with the socket lock.Cc: Petr Matousek
Signed-off-by: Jesper Dangaard Brouer
Acked-by: Eric Dumazet
Acked-by: Stephen Hemminger
Signed-off-by: David S. Miller
10 Mar, 2011
1 commit
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Signed-off-by: Stephen Hemminger
Signed-off-by: David S. Miller
18 Oct, 2010
1 commit
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The patch below updates broken web addresses in the kernel
Signed-off-by: Justin P. Mattock
Cc: Maciej W. Rozycki
Cc: Geert Uytterhoeven
Cc: Finn Thain
Cc: Randy Dunlap
Cc: Matt Turner
Cc: Dimitry Torokhov
Cc: Mike Frysinger
Acked-by: Ben Pfaff
Acked-by: Hans J. Koch
Reviewed-by: Finn Thain
Signed-off-by: Jiri Kosina
29 Jan, 2008
1 commit
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Signed-off-by: Ilpo Järvinen
Signed-off-by: Herbert Xu
Signed-off-by: David S. Miller
29 Nov, 2007
1 commit
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Lachlan Andrew observed that my TCP-Illinois implementation uses the
beta value incorrectly:
The parameter beta in the paper specifies the amount to decrease
*by*: that is, on loss,
W
Signed-off-by: Herbert Xu
31 Jul, 2007
1 commit
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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
Signed-off-by: David S. Miller
18 Jul, 2007
1 commit
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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
Signed-off-by: David S. Miller
16 Jun, 2007
1 commit
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Commit 164891aadf1721fca4dce473bb0e0998181537c6 broke RTT
sampling of congestion control modules. Inaccurate timestamps
could be fed to them without providing any way for them to
identify such cases. Previously RTT sampler was called only if
FLAG_RETRANS_DATA_ACKED was not set filtering inaccurate
timestamps nicely. In addition, the new behavior could give an
invalid timestamp (zero) to RTT sampler if only skbs with
TCPCB_RETRANS were ACKed. This solves both problems.Signed-off-by: Ilpo Järvinen
Signed-off-by: David S. Miller
26 Apr, 2007
4 commits
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To avoid raw division, use ktime_to_timeval() to get usec.
Signed-off-by: YOSHIFUJI Hideaki
Signed-off-by: David S. Miller -
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/settingsSigned-off-by: Stephen Hemminger
Signed-off-by: David S. Miller -
This version more closely matches the paper, and fixes several
math errors. The biggest difference is that it updates alpha/beta
once per RTTSigned-off-by: Stephen Hemminger
Signed-off-by: David S. Miller -
This is an implementation of TCP Illinois invented by Shao Liu
at University of Illinois. It is a another variant of Reno which adapts
the alpha and beta parameters based on RTT. The basic idea is to increase
window less rapidly as delay approaches the maximum. See the papers
and talks to get a more complete description.Signed-off-by: Stephen Hemminger
Signed-off-by: David S. Miller
