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Slow network speed inside CT [message #52832] Fri, 12 May 2017 22:55 Go to next message
creiss is currently offline  creiss
Messages: 4
Registered: February 2015
Location: Germany
Junior Member

From: *dip0.t-ipconnect.de
Hey folks,

I am running OpenVZ Distribution 7 (yum updated to latest). I am observing some weird abnormaliy: If I run a freshly installed VM and download something from a fast enough mirror I usually average around 800mbit/s. If I run the same download from the same mirrors from inside a freshly spawned CT I am averaged at around 100mbit/s. All CT/VMs are Centos7, with no modifications to either the OpenVZ Node nor to either CT nor VM.

Recreating either CT/VM will yield same results. Writing into a tmpfs mount to rule out the disk IO does only marginaly affect the results. CPUs (Cool are idle. The OpenVZ node is empty, no other machine is running (not yet productive).

I am in both cases (ct/vm) using routed with a 10.7.0.0/24 network routing through my OpenVZ with does NATing:

iptables -t nat -A POSTROUTING -o br0 -s 10.7.0.0/24 -j SNAT --to-source 1.2.3.4

I am adding network configuration to CT with

prlc ${prl_bin} set ${_arg_name} --iface venet0 --ipadd ${_arg_ip}

and to VMs with

${prl_bin} set ${_arg_name} --device-del net0
${prl_bin} set ${_arg_name} --device-add net --type routed --ipadd ${_arg_ip}

I am out of my wits; something makes the CT really really crawl when everything else is pretty much identical.
Any clue is greatly appreciated!
-Chris
Re: Slow network speed inside CT [message #52833 is a reply to message #52832] Sun, 14 May 2017 14:05 Go to previous message
creiss is currently offline  creiss
Messages: 4
Registered: February 2015
Location: Germany
Junior Member

From: *dip0.t-ipconnect.de
Something I noticed: It seems to start of rather ok'ish @40MB, but then goes down to a steady 10MB/s.
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