Most of the description that follows comes from my mail to
netdev (some editing done):

Main obstacle to FRTO use is its deployment as it has to be on
the sender side where as wireless link is often the receiver's
access link. Take initiative on behalf of unlucky receivers and
enable it by default in future Linux TCP senders. Also IETF
seems to interested in advancing FRTO from experimental [1].

How does FRTO help?
===================

FRTO detects spurious RTOs and avoids a number of unnecessary
retransmissions and a couple of other problems that can arise
due to incorrect guess made at RTO (i.e., that segments were
lost when they actually got delayed which is likely to occur
e.g. in wireless environments with link-layer retransmission).
Though FRTO cannot prevent the first (potentially unnecessary)
retransmission at RTO, I suspect that it won't cost that much
even if you have to pay for each bit (won't be that high
percentage out of all packets after all :-)). However, usually
when you have a spurious RTO, not only the first segment
unnecessarily retransmitted but the *whole window*. It goes like
this: all cumulative ACKs got delayed due to in-order delivery,
then TCP will actually send 1.5*original cwnd worth of data in
the RTO's slow-start when the delayed ACKs arrive (basically the
original cwnd worth of it unnecessarily). In case one is
interested in minimizing unnecessary retransmissions e.g. due to
cost, those rexmissions must never see daylight. Besides, in the
worst case the generated burst overloads the bottleneck buffers
which is likely to significantly delay the further progress of
the flow. In case of ll rexmissions, ACK compression often
occurs at the same time making the burst very "sharp edged" (in
that case TCP often loses most of the segments above high_seq
=> very bad performance too). When FRTO is enabled, those
unnecessary retransmissions are fully avoided except for the
first segment and the cwnd behavior after detected spurious RTO
is determined by the response (one can tune that by sysctl).

Basic version (non-SACK enhanced one), FRTO can fail to detect
spurious RTO as spurious and falls back to conservative
behavior. ACK lossage is much less significant than reordering,
usually the FRTO can detect spurious RTO if at least 2
cumulative ACKs from original window are preserved (excluding
the ACK that advances to high_seq). With SACK-enhanced version,
the detection is quite robust.

FRTO should remove the need to set a high lower bound for the
RTO estimator due to delay spikes that occur relatively common
in some environments (esp. in wireless/cellular ones).

[1] http://www1.ietf.org/mail-archive/web/tcpm/current/msg02862.htmlSigned-off-by: NIlpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Since the SACK enhanced FRTO was added, the code has been
under test numerous times so remove "experimental" claim
from the documentation. Also be a bit more verbose about
the usage.
Signed-off-by: NIlpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Basically this change enables it, previously other undo_marker
users were left with nothing. Reverse undo_marker logic
completely to get it set right in CA_Loss. On the other hand,
when spurious RTO is detected, clear it. Clearing might be too
heavy for some scenarios but seems safe enough starting point
for now and shouldn't have much effect except in majority of
cases (if in any).

By adding a new FLAG_ we avoid looping through write_queue when
RTO occurs.
Signed-off-by: NIlpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Implements following cleanups:
- Comment re-placement (CodingStyle)
- tcp_tso_acked() local (wrapper-like) variable removal
  (readability)
- __-types removed (IMHO they make local variables jumpy looking
  and just was space)
- acked -> flag (naming conventions elsewhere in TCP code)
- linebreak adjustments (readability)
- nested if()s combined (reduced indentation)
- clarifying newlines added
Signed-off-by: NIlpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The accounting code is pretty much the same, so it's a shame
we do it in two places.

I'm not too sure if added fully_acked check in MTU probing is
really what we want perhaps the added end_seq could be used in
the after() comparison.
Signed-off-by: NIlpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

In addition, fix its function comment spacing.
Signed-off-by: NIlpo Järvinen <ilpo.jarvinen@helsinki.fi>

Substraction for fackets_out is unconditional when snd_una
advances, thus there's no need to do it inside the loop. Just
make sure correct bounds are honored.
Signed-off-by: NIlpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

In general, it should not be necessary to call tcp_fragment for
already SACKed skbs, but it's better to be safe than sorry. And
indeed, it can be called from sacktag when a DSACK arrives or
some ACK (with SACK) reordering occurs (sacktag could be made
to avoid the call in the latter case though I'm not sure if it's
worth of the trouble and added complexity to cover such marginal
case).

The collapse case has return for SACKED_ACKED case earlier, so
just WARN_ON if internal inconsistency is detected for some
reason.
Signed-off-by: NIlpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

The remaining warning in phy.c will be fixed later.
Signed-off-by: NMichael Buesch <mb@bu3sch.de>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

Note: we still have several fishy areas - mcast filter
and vlan handling.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

amd8111e_calc_coalesce() ends up with insane values of tx_data_rate since
->tx_bytes increments missing conversion from little- to host-endian
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

Layout of opts2 is
: MSB(vlan_tag) : LSB(vlan_tag) : flags : 0 :
regardless of the host endianness.  On little-endian
the current code ends up with the right values, but
on big-endian it blows.  In r8169.c the same bug
had been fixed in commit d35da12a40426184b1d0844104b1d464753eba19
(r8169: endianness fixes).
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

maintainer change for s390 networking
Signed-off-by: NUrsula Braun <braunu@de.ibm.com>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

Signed-off-by: NVitaly Bordug <vitb@kernel.crashing.org>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

Signed-off-by: NVitaly Bordug <vitb@kernel.crashing.org>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

 Rename NET_SB1250_MAC to SB1250_MAC to follow the convention.
Signed-off-by: NMaciej W. Rozycki <macro@linux-mips.org>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

 The SB1250 network interfaces are Gigabit Ethernet ones.  Move the
Kconfig entry to the appropriate section and add some help text.
Signed-off-by: NMaciej W. Rozycki <macro@linux-mips.org>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

Resubmitting the patch.

This patch improves ethtool support for printing correct ring statistics,
segmentation offload status, etc.

Signed-off by: Dhananjay Phadke <dhananjay@netxen.com>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

Based on BenH's earlier work, this is a new version of the EMAC driver
for the built-in ethernet found on PowerPC 4xx embedded CPUs.  The
same ASIC is also found in the Axon bridge chip.  This new version is
designed to work in the arch/powerpc tree, using the device tree to
probe the device, rather than the old and ugly arch/ppc OCP layer.

This driver is designed to sit alongside the old driver (that lies in
drivers/net/ibm_emac and this one in drivers/net/ibm_newemac).  The
old driver is left in place to support arch/ppc until arch/ppc itself
reaches its final demise (not too long now, with luck).

This driver still has a number of things that could do with cleaning
up, but I think they can be fixed up after merging.  Specifically:
	- Should be adjusted to properly use the dma mapping API.
Axon needs this.
	- Probe logic needs reworking, in conjuction with the general
probing code for of_platform devices.  The dependencies here between
EMAC, MAL, ZMII etc. make this complicated.  At present, it usually
works, because we initialize and register the sub-drivers before the
EMAC driver itself, and (being in driver code) runs after the devices
themselves have been instantiated from the device tree.
Signed-off-by: NDavid Gibson <david@gibson.dropbear.id.au>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

Since we are adding requirement for the PHYLIB for this driver, there should be a select for that

Cc: Robin Getz <robin.getz@analog.com>
Signed-off-by: NBryan Wu <bryan.wu@analog.com>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

 - add MDIO functions and register mdio bus
 - add phy abstraction layer (PAL) functions and use PAL API
 - test on STAMP537 board
Signed-off-by: NBryan Wu <bryan.wu@analog.com>
Acked-by: NJeff Garzik <jeff@garzik.org>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

Blackfin EMAC driver: add power management interface and change the bf537mac_reset to bf537mac_disable
Signed-off-by: NBryan Wu <bryan.wu@analog.com>
Acked-by: NJeff Garzik <jeff@garzik.org>
Signed-off-by: NJeff Garzik <jeff@garzik.org>

Alex Landau writes in the forums:
 Previously, changing the MAC address (e.g. via ifconfig) resulted
 in a generic function to be called that only changed a variable in
 memory. This patch also updated the Blackfin MAC address registers
 to filter the correct new MAC.
Signed-off-by: NAlex Landau <lirsb@yahoo.com>
Signed-off-by: NMike Frysinger <michael.frysinger@analog.com>
Signed-off-by: NBryan Wu <bryan.wu@analog.com>
Acked-by: NJeff Garzik <jeff@garzik.org>
Signed-off-by: NJeff Garzik <jeff@garzik.org>