linux-toradex.git/net/ipv4/tcp_vegas.c, branch v3.4.97 Linux kernel for Apalis and Colibri modules tcp: mark tcp_congestion_ops read_mostly 2011-03-10T08:40:17+00:00 Stephen Hemminger shemminger@vyatta.com 2011-03-10T08:40:17+00:00 a252bebe22155313ccdadc20b79f67a239dc9ecb Signed-off-by: Stephen Hemminger <shemminger@vyatta.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
tcp: tcp_vegas ssthresh bugfix 2009-05-26T05:44:59+00:00 Doug Leith doug.leith@nuim.ie 2009-05-26T05:44:59+00:00 c80a5cdfc5ca6533cb893154f546370da1fdb8f0 This patch fixes ssthresh accounting issues in tcp_vegas when cwnd decreases Signed-off-by: Doug Leith <doug.leith@nuim.ie> Signed-off-by: David S. Miller <davem@davemloft.net> 
This patch fixes ssthresh accounting issues in tcp_vegas when cwnd decreases

Signed-off-by: Doug Leith <doug.leith@nuim.ie>
Signed-off-by: David S. Miller <davem@davemloft.net>
tcp: tcp_vegas cong avoid fix 2008-12-09T08:13:04+00:00 Doug Leith doug.leith@nuim.ie 2008-12-09T08:13:04+00:00 8d3a564da34e5844aca4f991b73f8ca512246b23 This patch addresses a book-keeping issue in tcp_vegas.c. At present tcp_vegas does separate book-keeping of cwnd based on packet sequence numbers. A mismatch can develop between this book-keeping and tp->snd_cwnd due, for example, to delayed acks acking multiple packets. When vegas transitions to reno operation (e.g. following loss), then this mismatch leads to incorrect behaviour (akin to a cwnd backoff). This seems mostly to affect operation at low cwnds where delayed acking can lead to a significant fraction of cwnd being covered by a single ack, leading to the book-keeping mismatch. This patch modifies the congestion avoidance update to avoid the need for separate book-keeping while leaving vegas congestion avoidance functionally unchanged. A secondary advantage of this modification is that the use of fixed-point (via V_PARAM_SHIFT) and 64 bit arithmetic is no longer necessary, simplifying the code. Some example test measurements with the patched code (confirming no functional change in the congestion avoidance algorithm) can be seen at: http://www.hamilton.ie/doug/vegaspatch/ Signed-off-by: Doug Leith <doug.leith@nuim.ie> Signed-off-by: David S. Miller <davem@davemloft.net> 
This patch addresses a book-keeping issue in tcp_vegas.c.  At present
tcp_vegas does separate book-keeping of cwnd based on packet sequence
numbers.  A mismatch can develop between this book-keeping and
tp->snd_cwnd due, for example, to delayed acks acking multiple
packets.  When vegas transitions to reno operation (e.g. following
loss), then this mismatch leads to incorrect behaviour (akin to a cwnd
backoff).  This seems mostly to affect operation at low cwnds where
delayed acking can lead to a significant fraction of cwnd being
covered by a single ack, leading to the book-keeping mismatch.  This
patch modifies the congestion avoidance update to avoid the need for
separate book-keeping while leaving vegas congestion avoidance
functionally unchanged.  A secondary advantage of this modification is
that the use of fixed-point (via V_PARAM_SHIFT) and 64 bit arithmetic
is no longer necessary, simplifying the code.

Some example test measurements with the patched code (confirming no functional
change in the congestion avoidance algorithm) can be seen at:

http://www.hamilton.ie/doug/vegaspatch/

Signed-off-by: Doug Leith <doug.leith@nuim.ie>
Signed-off-by: David S. Miller <davem@davemloft.net>
tcp: tcp_vegas ssthresh bug fix 2008-12-05T01:17:18+00:00 Doug Leith doug.leith@nuim.ie 2008-12-05T01:17:18+00:00 a6af2d6ba5797c556fba0cd3a19e5f3bc9a99b76 This patch fixes a bug in tcp_vegas.c. At the moment this code leaves ssthresh untouched. However, this means that the vegas congestion control algorithm is effectively unable to reduce cwnd below the ssthresh value (if the vegas update lowers the cwnd below ssthresh, then slow start is activated to raise it back up). One example where this matters is when during slow start cwnd overshoots the link capacity and a flow then exits slow start with ssthresh set to a value above where congestion avoidance would like to adjust it. Signed-off-by: Doug Leith <doug.leith@nuim.ie> Signed-off-by: David S. Miller <davem@davemloft.net> 
This patch fixes a bug in tcp_vegas.c.  At the moment this code leaves
ssthresh untouched.  However, this means that the vegas congestion
control algorithm is effectively unable to reduce cwnd below the
ssthresh value (if the vegas update lowers the cwnd below ssthresh,
then slow start is activated to raise it back up).  One example where
this matters is when during slow start cwnd overshoots the link
capacity and a flow then exits slow start with ssthresh set to a value
above where congestion avoidance would like to adjust it.

Signed-off-by: Doug Leith <doug.leith@nuim.ie>
Signed-off-by: David S. Miller <davem@davemloft.net>
net: fix returning void-valued expression warnings 2008-05-01T09:47:38+00:00 Harvey Harrison harvey.harrison@gmail.com 2008-05-01T09:47:38+00:00 ab59859de1946a098b091308380179e92dc7683b drivers/net/8390.c:37:2: warning: returning void-valued expression drivers/net/bnx2.c:1635:3: warning: returning void-valued expression drivers/net/xen-netfront.c:1806:2: warning: returning void-valued expression net/ipv4/tcp_hybla.c:105:3: warning: returning void-valued expression net/ipv4/tcp_vegas.c:171:3: warning: returning void-valued expression net/ipv4/tcp_veno.c:123:3: warning: returning void-valued expression net/sysctl_net.c:85:2: warning: returning void-valued expression Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com> Acked-by: Alan Cox <alan@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
drivers/net/8390.c:37:2: warning: returning void-valued expression
drivers/net/bnx2.c:1635:3: warning: returning void-valued expression
drivers/net/xen-netfront.c:1806:2: warning: returning void-valued expression
net/ipv4/tcp_hybla.c:105:3: warning: returning void-valued expression
net/ipv4/tcp_vegas.c:171:3: warning: returning void-valued expression
net/ipv4/tcp_veno.c:123:3: warning: returning void-valued expression
net/sysctl_net.c:85:2: warning: returning void-valued expression

Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Acked-by: Alan Cox <alan@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
tcp: Overflow bug in Vegas 2008-04-30T08:04:03+00:00 Lachlan Andrew lachlan.andrew@gmail.com 2008-04-30T08:04:03+00:00 159131149c2f56c1da5ae5e23ab9d5acef4916d1 From: Lachlan Andrew <lachlan.andrew@gmail.com> There is an overflow bug in net/ipv4/tcp_vegas.c for large BDPs (e.g. 400Mbit/s, 400ms). The multiplication (old_wnd * vegas->baseRTT) << V_PARAM_SHIFT overflows a u32. [ Fix tcp_veno.c too, it has similar calculations. -DaveM ] Signed-off-by: David S. Miller <davem@davemloft.net> 
From: Lachlan Andrew <lachlan.andrew@gmail.com>

There is an overflow bug in net/ipv4/tcp_vegas.c for large BDPs
(e.g. 400Mbit/s, 400ms).  The multiplication (old_wnd *
vegas->baseRTT) << V_PARAM_SHIFT overflows a u32.

[ Fix tcp_veno.c too, it has similar calculations. -DaveM ]

Signed-off-by: David S. Miller <davem@davemloft.net>
[TCP]: Cong.ctrl modules: remove unused good_ack from cong_avoid 2008-01-28T22:55:41+00:00 Ilpo Järvinen ilpo.jarvinen@helsinki.fi 2007-12-01T22:47:59+00:00 c3a05c6050a339c92e49fae0ba77dbba0d41fd99 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> 
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] vegas: Fix a bug in disabling slow start by gamma parameter. 2007-10-30T05:37:25+00:00 Xiaoliang (David) Wei davidwei79@gmail.com 2007-10-30T03:24:36+00:00 c940587bf603b4295a7f5e9ff8fed123368a1ef7 TCP Vegas implementation has a bug in the process of disabling slow-start with gamma parameter. The bug may lead to extreme unfairness in the presence of early packet loss. See details in: http://www.cs.caltech.edu/~weixl/technical/ns2linux/known_linux/index.html#vegas Switch the order of "if (tp->snd_cwnd <= tp->snd_ssthresh)" statement and "if (diff > gamma)" statement to eliminate the problem. Signed-off-by: Xiaoliang (David) Wei <davidwei79@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net> 
TCP Vegas implementation has a bug in the process of disabling
slow-start with gamma parameter. The bug may lead to extreme
unfairness in the presence of early packet loss. See details in:
http://www.cs.caltech.edu/~weixl/technical/ns2linux/known_linux/index.html#vegas

Switch the order of "if (tp->snd_cwnd <= tp->snd_ssthresh)" statement
and "if (diff > gamma)" statement to eliminate the problem.

Signed-off-by: Xiaoliang (David) Wei <davidwei79@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
[TCP]: congestion control API pass RTT in microseconds 2007-07-31T09:27:57+00:00 Stephen Hemminger shemminger@linux-foundation.org 2007-07-26T06:49:34+00:00 30cfd0baf0a0c4329fff1ef4b622919297969ec8 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> 
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>
[TCP]: remove unused argument to cong_avoid op 2007-07-18T08:46:58+00:00 Stephen Hemminger shemminger@linux-foundation.org 2007-07-17T01:35:52+00:00 16751347a060a10c09b11593bb179fd5b0240c04 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> 
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>