Re: Slow speed of tcp connections in a network namespace

[Andrew Vagin <avagin@parallels.com>]

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On Sat, Dec 29, 2012 at 09:40:28AM -0800, Eric Dumazet wrote:
> On Sat, 2012-12-29 at 18:50 +0400, Andrew Vagin wrote:
> > On Sat, Dec 29, 2012 at 05:53:23AM -0800, Eric Dumazet wrote:
> > > > 3.8-rc1 is used for experiments.
> > > > 
> > > > Do you have any ideas where is a problem?
> > > 
> > > veth has absolutely no offload features
> > > 
> > > It needs some care...
> > > 
> > > At the very miminum, let TCP coalesce do its job by allowing SG
> > > 
> > > CC Michał Mirosław <mirq-linux@rere.qmqm.pl> for insights.
> > > 
> > > Please try following patch :
> > 
> > Hello Eric,
> > 
> > Thanks for your feedback.
> > 
> > With this patch the results is a bit better (~4MB/s), but it's much less
> > than in the root netns.
> 
> Please post your new tcpdump then ;)

I have rebooted the host and a speed in a netns is again about 1.7MB/s. I
don't know why it was 4MB/s in the previous time.

new tcpdump and netstat are attached

> 
> also post "netstat -s" from root and test ns after your wgets
> 
> 
> 

[-- Attachment #2: tcpdump.host.gz --]
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[-- Attachment #3: tcpdump.netns.host.gz --]
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[-- Attachment #4: tcpdump.netns.veth.gz --]
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[-- Attachment #5: netstat.host --]
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Ip:
    277536 total packets received
    20 forwarded
    0 incoming packets discarded
    202326 incoming packets delivered
    108228 requests sent out
    30 dropped because of missing route
Icmp:
    10 ICMP messages received
    0 input ICMP message failed.
    ICMP input histogram:
        destination unreachable: 5
        echo requests: 5
    6 ICMP messages sent
    0 ICMP messages failed
    ICMP output histogram:
        destination unreachable: 1
        echo replies: 5
IcmpMsg:
        InType3: 5
        InType8: 5
        OutType0: 5
        OutType3: 1
Tcp:
    1491 active connections openings
    12 passive connection openings
    14 failed connection attempts
    72 connection resets received
    2 connections established
    201920 segments received
    107815 segments send out
    0 segments retransmited
    0 bad segments received.
    1338 resets sent
Udp:
    387 packets received
    0 packets to unknown port received.
    0 packet receive errors
    389 packets sent
UdpLite:
TcpExt:
    3 invalid SYN cookies received
    4 TCP sockets finished time wait in fast timer
    63 delayed acks sent
    9 delayed acks further delayed because of locked socket
    236 packets directly queued to recvmsg prequeue.
    38600456 packets directly received from backlog
    298101 packets directly received from prequeue
    163501 packets header predicted
    27103 packets header predicted and directly queued to user
    2578 acknowledgments not containing data received
    1018 predicted acknowledgments
    15 connections reset due to unexpected data
    72 connections reset due to early user close
    TCPRcvCoalesce: 123
    TCPOFOQueue: 1187
IpExt:
    InBcastPkts: 9
    OutBcastPkts: 1
    InOctets: 296395504
    OutOctets: 6965311
    InBcastOctets: 2789
    OutBcastOctets: 165

[-- Attachment #6: netstat.netns --]
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Ip:
    25483 total packets received
    0 forwarded
    0 incoming packets discarded
    25483 incoming packets delivered
    14572 requests sent out
Icmp:
    4 ICMP messages received
    0 input ICMP message failed.
    ICMP input histogram:
        echo requests: 2
        echo replies: 2
    4 ICMP messages sent
    0 ICMP messages failed
    ICMP output histogram:
        echo request: 2
        echo replies: 2
IcmpMsg:
        InType0: 2
        InType8: 2
        OutType0: 2
        OutType8: 2
Tcp:
    1 active connections openings
    0 passive connection openings
    0 failed connection attempts
    0 connection resets received
    0 connections established
    25473 segments received
    14562 segments send out
    0 segments retransmited
    0 bad segments received.
    77 resets sent
Udp:
    6 packets received
    0 packets to unknown port received.
    0 packet receive errors
    6 packets sent
UdpLite:
TcpExt:
    38 delayed acks sent
    Quick ack mode was activated 2 times
    52 packets directly queued to recvmsg prequeue.
    4916752 packets directly received from backlog
    11584 packets directly received from prequeue
    12538 packets header predicted
    2649 packets header predicted and directly queued to user
    1 acknowledgments not containing data received
    2 DSACKs sent for old packets
    1 connections reset due to unexpected data
    TCPOFOQueue: 1580
IpExt:
    InOctets: 38201843
    OutOctets: 829966