Eric Lee / smarc-fsl-linux-kernel

17 Mar, 2020

1 commit

  • fa4cb9eba   tcp: fix stretch ACK bugs in Yeah ... Browse Code »

    Change Yeah to properly handle stretch ACKs in additive
    increase mode by passing in the count of ACKed packets
    to tcp_cong_avoid_ai().

    In addition, we re-implemented the scalable path using
    tcp_cong_avoid_ai() and removed the pkts_acked variable.

    Signed-off-by: Pengcheng Yang
    Signed-off-by: David S. Miller

    Pengcheng Yang
     

21 May, 2019

1 commit

  • 09c434b8a   treewide: Add SPDX license identifier for more missed files ... Browse Code »

    Add SPDX license identifiers to all files which:

    - Have no license information of any form

    - Have MODULE_LICENCE("GPL*") inside which was used in the initial
    scan/conversion to ignore the file

    These files fall under the project license, GPL v2 only. The resulting SPDX
    license identifier is:

    GPL-2.0-only

    Signed-off-by: Thomas Gleixner
    Signed-off-by: Greg Kroah-Hartman

    Thomas Gleixner
     

07 Aug, 2017

1 commit

  • f1722a1be   tcp: consolidate congestion control undo functions ... Browse Code »

    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

    Yuchung Cheng
     

22 Nov, 2016

1 commit

  • 85f7e7508   tcp: add cwnd_undo functions to various tcp cc algorithms ... Browse Code »

    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

    Florian Westphal
     

09 Sep, 2016

1 commit

  • db7196a0d   tcp: cwnd does not increase in TCP YeAH ... Browse Code »

    Commit 76174004a0f19785a328f40388e87e982bbf69b9
    (tcp: do not slow start when cwnd equals ssthresh )
    introduced regression in TCP YeAH. Using 100ms delay 1% loss virtual
    ethernet link kernel 4.2 shows bandwidth ~500KB/s for single TCP
    connection and kernel 4.3 and above (including 4.8-rc4) shows bandwidth
    ~100KB/s.
    That is caused by stalled cwnd when cwnd equals ssthresh. This patch
    fixes it by proper increasing cwnd in this case.

    Signed-off-by: Artem Germanov
    Acked-by: Dmitry Adamushko
    Signed-off-by: David S. Miller

    Artem Germanov
     

12 May, 2016

1 commit

  • 756ee1729   tcp: replace cnt & rtt with struct in pkts_acked() ... Browse Code »

    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

    Lawrence Brakmo
     

12 Jan, 2016

1 commit

  • 83d15e70c   tcp_yeah: don't set ssthresh below 2 ... Browse Code »

    For tcp_yeah, use an ssthresh floor of 2, the same floor used by Reno
    and CUBIC, per RFC 5681 (equation 4).

    tcp_yeah_ssthresh() was sometimes returning a 0 or negative ssthresh
    value if the intended reduction is as big or bigger than the current
    cwnd. Congestion control modules should never return a zero or
    negative ssthresh. A zero ssthresh generally results in a zero cwnd,
    causing the connection to stall. A negative ssthresh value will be
    interpreted as a u32 and will set a target cwnd for PRR near 4
    billion.

    Oleksandr Natalenko reported that a system using tcp_yeah with ECN
    could see a warning about a prior_cwnd of 0 in
    tcp_cwnd_reduction(). Testing verified that this was due to
    tcp_yeah_ssthresh() misbehaving in this way.

    Reported-by: Oleksandr Natalenko
    Signed-off-by: Neal Cardwell
    Signed-off-by: Yuchung Cheng
    Signed-off-by: Eric Dumazet
    Signed-off-by: David S. Miller

    Neal Cardwell
     

29 Jan, 2015

1 commit

  • e73ebb088   tcp: stretch ACK fixes prep ... Browse Code »

    LRO, GRO, delayed ACKs, and middleboxes can cause "stretch ACKs" that
    cover more than the RFC-specified maximum of 2 packets. These stretch
    ACKs can cause serious performance shortfalls in common congestion
    control algorithms that were designed and tuned years ago with
    receiver hosts that were not using LRO or GRO, and were instead
    politely ACKing every other packet.

    This patch series fixes Reno and CUBIC to handle stretch ACKs.

    This patch prepares for the upcoming stretch ACK bug fix patches. It
    adds an "acked" parameter to tcp_cong_avoid_ai() to allow for future
    fixes to tcp_cong_avoid_ai() to correctly handle stretch ACKs, and
    changes all congestion control algorithms to pass in 1 for the ACKed
    count. It also changes tcp_slow_start() to return the number of packet
    ACK "credits" that were not processed in slow start mode, and can be
    processed by the congestion control module in additive increase mode.

    In future patches we will fix tcp_cong_avoid_ai() to handle stretch
    ACKs, and fix Reno and CUBIC handling of stretch ACKs in slow start
    and additive increase mode.

    Reported-by: Eyal Perry
    Signed-off-by: Neal Cardwell
    Signed-off-by: Yuchung Cheng
    Signed-off-by: Eric Dumazet
    Signed-off-by: David S. Miller

    Neal Cardwell
     

02 Sep, 2014

1 commit

  • 688d1945b   tcp: whitespace fixes ... Browse Code »

    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

    stephen hemminger
     

04 May, 2014

1 commit

27 Feb, 2014

1 commit

  • 740b0f184   tcp: switch rtt estimations to usec resolution ... Browse Code »

    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:29559

    Updated 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
    10.246.11.51

    Old 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
    10.246.11.51

    With 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

    Eric Dumazet
     

14 Feb, 2014

1 commit

27 Dec, 2013

2 commits

05 Nov, 2013

1 commit

  • 9f9843a75   tcp: properly handle stretch acks in slow start ... Browse Code »

    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

    Yuchung Cheng
     

31 Mar, 2011

1 commit

10 Mar, 2011

1 commit

24 Nov, 2009

1 commit

  • 9d4fb27db   net/ipv4: Move && and || to end of previous line ... Browse Code »

    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
    Signed-off-by: David S. Miller

    Joe Perches
     

02 Mar, 2009

1 commit

  • 758ce5c8d   tcp: add helper for AI algorithm ... Browse Code »

    It seems that implementation in yeah was inconsistent to what
    other did as it would increase cwnd one ack earlier than the
    others do.

    Size benefits:

    bictcp_cong_avoid | -36
    tcp_cong_avoid_ai | +52
    bictcp_cong_avoid | -34
    tcp_scalable_cong_avoid | -36
    tcp_veno_cong_avoid | -12
    tcp_yeah_cong_avoid | -38

    = -104 bytes total

    Signed-off-by: Ilpo Järvinen
    Signed-off-by: David S. Miller

    Ilpo Järvinen
     

03 Nov, 2008

1 commit

29 Jan, 2008

1 commit

31 Jul, 2007

1 commit

  • 30cfd0baf   [TCP]: congestion control API pass RTT in microseconds ... Browse Code »

    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

    Stephen Hemminger
     

18 Jul, 2007

1 commit

26 Apr, 2007

5 commits

  • 7752237e9   [TCP] TCP YEAH: Use vegas dont copy it. ... Browse Code »

    Rather than using a copy of vegas code, the YEAH code should just have
    it exported so there is common code.

    Signed-off-by: Stephen Hemminger
    Signed-off-by: David S. Miller

    Stephen Hemminger
     
  • 164891aad   [TCP]: Congestion control API update. ... Browse Code »

    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
    Signed-off-by: David S. Miller

    Stephen Hemminger
     
  • 43e683926   [TCP] TCP Yeah: cleanup ... Browse Code »

    Eliminate need for full 6/4/64 divide to compute queue.
    Variable maxqueue was really a constant.
    Fix indentation.

    Signed-off-by: Stephen Hemminger
    Signed-off-by: David S. Miller

    Stephen Hemminger
     
  • 3927f2e8f   [NET]: div64_64 consolidate (rev3) ... Browse Code »

    Here is the current version of the 64 bit divide common code.

    Signed-off-by: Stephen Hemminger
    Signed-off-by: David S. Miller

    Stephen Hemminger
     
  • 5ef814753   [TCP] YeAH-TCP: algorithm implementation ... Browse Code »

    YeAH-TCP is a sender-side high-speed enabled TCP congestion control
    algorithm, which uses a mixed loss/delay approach to compute the
    congestion window. It's design goals target high efficiency, internal,
    RTT and Reno fairness, resilience to link loss while keeping network
    elements load as low as possible.

    For further details look here:
    http://wil.cs.caltech.edu/pfldnet2007/paper/YeAH_TCP.pdf

    Signed-off-by: Angelo P. Castellani
    Signed-off-by: David S. Miller

    Angelo P. Castellani