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Re: coverage

To: kuznet@xxxxxxxxxxxxx
Subject: Re: coverage
From: Andrew Morton <andrewm@xxxxxxxxxx>
Date: Mon, 03 Apr 2000 09:50:19 +0000
Cc: netdev@xxxxxxxxxxx
References: <38E73398.E1727365@xxxxxxxxxx> from "Andrew Morton" at Apr 2, 0 04:13:15 pm <200004021618.UAA06079@xxxxxxxxxxxxx>
Sender: owner-netdev@xxxxxxxxxxx
kuznet@xxxxxxxxxxxxx wrote:
> It is easy. "ping -f" does not create any real load on the network,
> it is pure latency test, when there is always only one packet in flight.

I use 'ping -l 100000'

     -l preload
             If preload is specified, ping sends that many packets as
fast as
             possible before falling into its normal mode of behavior. 
             the super-user may use this option.

> Do not use it. Just write simple program, sending small udp packets
> without gaps, or use tools sort of netperf. To create extremal load,
> it is possible to use pgen tool by Robert Olsson
> (, it is a bit out of date,
> but easy to update.

Thanks - I'll look into it.

> >   - Tx stuck, invoke tx_timeout
> I think any man working with network has in his table some broken hub,
> which generates only collisions. 8) Mmm... what will occur if to plug
> crossed pair to two hub slots? Will it simulate broken hub then?
> (I did not advise you to do this! 8))
> Seriously, you can just to skip some TX ring refilling deliberately
> to trigger this condition.

Thanks again.


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