[LARTC] IMQ slows computer to a crawl - SOLVED

[LARTC] IMQ slows computer to a crawl - SOLVED

[gypsy]

gypsy wrote:
> 
> I am attempting to implement IMQ on a 2.4.31 version kernel with
> iptables 1.3.3.
> 
> I am following the example at http://www.linuximq.net/usage.html.  When
> I enter the line
> iptables -t mangle -A POSTROUTING -o eth1 -j IMQ --todev1
> 
> (eth1 is the external interface), the computer slows to a crawl.  OK,
> the CPU is only an AMD K6 233 which is not the world's greatest CPU, but
> egress shaping is done at acceptable speed.
> 
> Neither top nor free is any help.  top says the system is using 35% and
> user about 1%, with load averages in the range of 0.2x, 0.2x and 0.1x
> and top itself is at the top of the list.  free says 3388 free mem and
> 780 used swap.
> 
> Even attaching to a non connected device (change eth1 to eth2 in the
> above iptables line) creates this condition!??
> 
> Does anyone have any suggestions as to what might cause this huge
> slowdown?  How do I troubleshoot this?  I'll have to reimplement
> policing if I can't make IMQ work.
> 
> Thanks for any assistance.
> --
> gypsy

The answer is that the wrong IMQ device was specified.

I loaded imq with:
modprobe imq numdevs=1

That makes the --todev 0 not 1.  Moreover, I was in the wrong mangle
chain.
WRONG: iptables -t mangle -A POSTROUTING -o eth1 -j IMQ --todev 1
RIGHT: iptables -t mangle -A PREROUTING -i eth1 -j IMQ --todev 0

So much for the documentation at http://www.linuximq.net/usage.html
<shrug>.  Thanks to http://wiki.nix.hu/cgi-bin/twiki/view/IMQ/WebHome
--
gypsy
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