[Users] CentOS 6: default inbound traffic limited for CT's

[Kirill Korotaev]

Mattias,

1. The same doesn't happen on the very same host system (VE0)? Inside container only?
2. Are you using venet or bridged networking?

Thanks,
Kirill

On Feb 21, 2012, at 00:31 , Mattias Geniar wrote:

> Hi,
> 
> I'm running OpenVZ on a CentOS 6 x64 machine with a stable kernel
> (2.6.32-042stab049.6) and have even tried the issue below on the
> test-branch (2.6.32-042stab052.2).
> The issue I'm experiencing is also reported by Fredericep on the forum
> but never got any follow-up:
> http://forum.openvz.org/index.php?t=tree&goto=44238&&srch=inbound#msg_44
> 238
> 
> It's the exact same problem: my hardware node runs perfectly fine, it
> has both full in- and outgoing networking speed. I can consistently
> (3hours+ as tested) download files at my full line speed.
> Whenever I try to same in a container, I can get a quick burst of
> network traffic for a few seconds (10MB/s+) and then fall back to
> 10-200Kb/s, it varies.
> 
> My first troubleshooting went to incoming traffic shaping for the
> eth0/venet0 interface, but that's not the case:
>  # tc -s qdisc ls dev eth0
>  qdisc mq 0: root
>   Sent 65350399 bytes 363366 pkt (dropped 0, overlimits 0 requeues 0)
>   rate 0bit 0pps backlog 0b 0p requeues 0
> 
>  # tc qdisc del dev eth0 root
>  RTNETLINK answers: No such file or directory
> 
> But this is a default install and it doesn't have any traffic shaping
> rules active. Neither does it have iptables active. It's all still
> running the default OpenVZ stack.
> 
> Second idea was a possible hit of TCPSNDBUF or TCPRCVBUF as the defaults
> (1720320) are rather low. But even changing it to something idiotic like
> 9223372036854775807 didn't make a difference. The /proc/user_beancounter
> also didn't report any failed packets.
> 
> When tcpdumping the stream, I don't see anything abnormal except that
> it's just slow traffic. Nothing out of the ordinary at first glance.
> 
> I'm looking for any advice on how to troubleshoot this, as I believe
> this may very well be a CentOS 6 kernel bug - but to prove that, I would
> of course need to dive deeper which is where my train of thought kind of
> ends.
> 
> I look forward to any reply/idea this list may give me.
> 
> Mattias Geniar
> 
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