Commits · 382f598fb66b14a8451f2794abf70ea7b5826c96 · Kirill Smelkov / linux

05 Apr, 2019 31 commits

tipc: reduce duplicate packets for unicast traffic · 382f598f

Tuong Lien authored Apr 04, 2019

For unicast transmission, the current NACK sending althorithm is over-
active that forces the sending side to retransmit a packet that is not
really lost but just arrived at the receiving side with some delay, or
even retransmit same packets that have already been retransmitted
before. As a result, many duplicates are observed also under normal
condition, ie. without packet loss.

One example case is: node1 transmits 1 2 3 4 10 5 6 7 8 9, when node2
receives packet #10, it puts into the deferdq. When the packet #5 comes
it sends NACK with gap [6 - 9]. However, shortly after that, when
packet #6 arrives, it pulls out packet #10 from the deferfq, but it is
still out of order, so it makes another NACK with gap [7 - 9] and so on
... Finally, node1 has to retransmit the packets 5 6 7 8 9 a number of
times, but in fact all the packets are not lost at all, so duplicates!

This commit reduces duplicates by changing the condition to send NACK,
also restricting the retransmissions on individual packets via a timer
of about 1ms. However, it also needs to say that too tricky condition
for NACKs or too long timeout value for retransmissions will result in
performance reducing! The criterias in this commit are found to be
effective for both the requirements to reduce duplicates but not affect
performance.

The tipc_link_rcv() is also improved to only dequeue skb from the link
deferdq if it is expected (ie. its seqno <= rcv_nxt).
Acked-by: Ying Xue <ying.xue@windriver.com>
Acked-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: Tuong Lien <tuong.t.lien@dektech.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

382f598f

tipc: improve TIPC throughput by Gap ACK blocks · 9195948f

Tuong Lien authored Apr 04, 2019

During unicast link transmission, it's observed very often that because
of one or a few lost/dis-ordered packets, the sending side will fastly
reach the send window limit and must wait for the packets to be arrived
at the receiving side or in the worst case, a retransmission must be
done first. The sending side cannot release a lot of subsequent packets
in its transmq even though all of them might have already been received
by the receiving side.
That is, one or two packets dis-ordered/lost and dozens of packets have
to wait, this obviously reduces the overall throughput!

This commit introduces an algorithm to overcome this by using "Gap ACK
blocks". Basically, a Gap ACK block will consist of <ack, gap> numbers
that describes the link deferdq where packets have been got by the
receiving side but with gaps, for example:

      link deferdq: [1 2 3 4      10 11      13 14 15       20]
--> Gap ACK blocks:       <4, 5>,   <11, 1>,      <15, 4>, <20, 0>

The Gap ACK blocks will be sent to the sending side along with the
traditional ACK or NACK message. Immediately when receiving the message
the sending side will now not only release from its transmq the packets
ack-ed by the ACK but also by the Gap ACK blocks! So, more packets can
be enqueued and transmitted.
In addition, the sending side can now do "multi-retransmissions"
according to the Gaps reported in the Gap ACK blocks.

The new algorithm as verified helps greatly improve the TIPC throughput
especially under packet loss condition.

So far, a maximum of 32 blocks is quite enough without any "Too few Gap
ACK blocks" reports with a 5.0% packet loss rate, however this number
can be increased in the furture if needed.

Also, the patch is backward compatible.
Acked-by: Ying Xue <ying.xue@windriver.com>
Acked-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: Tuong Lien <tuong.t.lien@dektech.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

9195948f

Merge branch 'genphy-ability' · 29502bb1

David S. Miller authored Apr 04, 2019

Heiner Kallweit says:

====================
net: phy: use generic PHY ability readers if callback get_features isn't set

Meanwhile we have generic functions for reading the abilities of
Clause 22 / 45 PHY's. This allows to use them as fallback in case
callback get_features isn't set. Benefit is the reduction of
boilerplate code in PHY drivers.

v2:
- adjust a comment in patch 1 to match the code
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

29502bb1

net: phy: realtek: remove setting callback get_features and use phylib fallback · 32a069d8

Heiner Kallweit authored Apr 03, 2019

Now that phylib uses genphy_read_abilities() as fallback, we don't have
to set callback get_features any longer.
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

32a069d8

net: phy: allow a PHY driver to define neither features nor get_features · a1deab17

Heiner Kallweit authored Apr 03, 2019

Meanwhile we have generic functions for reading the abilities of
Clause 22 / 45 PHY's. This allows to use them as fallback in case
callback get_features isn't set. Benefit is the reduction of
boilerplate code in PHY drivers.

v2:
- adjust the comment in phy_driver_register to match the code
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

a1deab17

net: bridge: mcast: remove unused br_ip_equal function · e177163d

Nikolay Aleksandrov authored Apr 03, 2019

Since the mcast conversion to rhashtable this function has been unused, so
remove it.
Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

e177163d

Revert "r8169: use netif_receive_skb_list batching" · 448a2413

Heiner Kallweit authored Apr 03, 2019

This reverts commit 6578229d.
netif_receive_skb_list() doesn't support GRO, therefore we may have
scenarios with decreased performance. See discussion here [0].

[0] https://marc.info/?t=155403847400001&r=1&w=2Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

448a2413

tcp: Accept ECT on SYN in the presence of RFC8311 · f6fee16d

Tilmans, Olivier (Nokia - BE/Antwerp) authored Apr 03, 2019

Linux currently disable ECN for incoming connections when the SYN
requests ECN and the IP header has ECT(0)/ECT(1) set, as some
networks were reportedly mangling the ToS byte, hence could later
trigger false congestion notifications.

RFC8311 §4.3 relaxes RFC3168's requirements such that ECT can be set
one TCP control packets (including SYNs). The main benefit of this
is the decreased probability of losing a SYN in a congested
ECN-capable network (i.e., it avoids the initial 1s timeout).
Additionally, this allows the development of newer TCP extensions,
such as AccECN.

This patch relaxes the previous check, by enabling ECN on incoming
connections using SYN+ECT if at least one bit of the reserved flags
of the TCP header is set. Such bit would indicate that the sender of
the SYN is using a newer TCP feature than what the host implements,
such as AccECN, and is thus implementing RFC8311. This enables
end-hosts not supporting such extensions to still negociate ECN, and
to have some of the benefits of using ECN on control packets.
Signed-off-by: Olivier Tilmans <olivier.tilmans@nokia-bell-labs.com>
Suggested-by: Bob Briscoe <research@bobbriscoe.net>
Cc: Koen De Schepper <koen.de_schepper@nokia-bell-labs.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Acked-by: Yuchung Cheng <ycheng@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

f6fee16d

Merge branch 'net-extend-devlink-port-attrs-with-switch-ID' · 6124d067

David S. Miller authored Apr 04, 2019

Jiri Pirko says:

====================
net: extend devlink port attrs with switch ID

Extend devlink port attrs to contain switch ID and change drivers that
register devlink ports to use that.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

6124d067