Eric Lee / smarc-fsl-linux-kernel

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
     

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
     

10 Jul, 2015

1 commit

  • 071d5080e   tcp: add tcp_in_slow_start helper ... Browse Code »

    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

    Yuchung Cheng
     

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
     

31 Jul, 2014

1 commit

  • 45a07695b   tcp: Fix integer-overflows in TCP veno ... Browse Code »

    In veno we do a multiplication of the cwnd and the rtt. This
    may overflow and thus their result is stored in a u64. However, we first
    need to cast the cwnd so that actually 64-bit arithmetic is done.

    A first attempt at fixing 76f1017757aa0 ([TCP]: TCP Veno congestion
    control) was made by 159131149c2 (tcp: Overflow bug in Vegas), but it
    failed to add the required cast in tcp_veno_cong_avoid().

    Fixes: 76f1017757aa0 ([TCP]: TCP Veno congestion control)
    Signed-off-by: Christoph Paasch
    Signed-off-by: David S. Miller

    Christoph Paasch
     

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
     

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
     

10 Mar, 2011

1 commit

18 Oct, 2010

1 commit

  • 631dd1a88   Update broken web addresses in the kernel. ... Browse Code »

    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

    Justin P. Mattock
     

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
     

01 May, 2008

1 commit

  • ab59859de   net: fix returning void-valued expression warnings ... Browse Code »

    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
    Acked-by: Alan Cox
    Signed-off-by: David S. Miller

    Harvey Harrison
     

30 Apr, 2008

1 commit

  • 159131149   tcp: Overflow bug in Vegas ... Browse Code »

    From: Lachlan Andrew

    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

    Lachlan Andrew
     

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

16 Jun, 2007

1 commit

  • b9ce204f0   [TCP]: Congestion control API RTT sampling fix ... Browse Code »

    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

    Ilpo Järvinen
     

26 Apr, 2007

2 commits

23 Sep, 2006

2 commits

18 Jun, 2006

2 commits

  • 72dc5b922   [TCP]: Minimum congestion window consolidation. ... Browse Code »

    Many of the TCP congestion methods all just use ssthresh
    as the minimum congestion window on decrease. Rather than
    duplicating the code, just have that be the default if that
    handle in the ops structure is not set.

    Minor behaviour change to TCP compound. It probably wants
    to use this (ssthresh) as lower bound, rather than ssthresh/2
    because the latter causes undershoot on loss.

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

    Stephen Hemminger
     
  • 76f101775   [TCP]: TCP Veno congestion control ... Browse Code »

    TCP Veno module is a new congestion control module to improve TCP
    performance over wireless networks. The key innovation in TCP Veno is
    the enhancement of TCP Reno/Sack congestion control algorithm by using
    the estimated state of a connection based on TCP Vegas. This scheme
    significantly reduces "blind" reduction of TCP window regardless of
    the cause of packet loss.

    This work is based on the research paper "TCP Veno: TCP Enhancement
    for Transmission over Wireless Access Networks." C. P. Fu, S. C. Liew,
    IEEE Journal on Selected Areas in Communication, Feb. 2003.

    Original paper and many latest research works on veno:
    http://www.ntu.edu.sg/home/ascpfu/veno/veno.html

    Signed-off-by: Bin Zhou
    Cheng Peng Fu
    Signed-off-by: Stephen Hemminger
    Signed-off-by: David S. Miller

    Bin Zhou