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Re: Intel Pro/1000 MT and strange ping RTTs



Any luck replicating this?  Does anyone else have any ideas?

--- Henrique de Moraes Holschuh <hmh@debian.org> wrote:

> On Sun, 12 Feb 2006, Mark Flocco wrote:
> > session.  However, during times of high traffic (~8Mbps), the RTTs
> 
> 8Mbits/s or 8Mbytes/s ? Anyway neither is much of a high traffic for
> an
> e1000 on a modern host, unless you're using a very, very low MTU (and
> maybe
> not even then).
> 
> > increase, showing stress.  Not sure if that's typical on other
> 
> I wouldn't call that stress, unless your switch is really awful.  But
> an RTT
> increase is expected, there's now a queue to get through.  I asked
> because
> that also increases jitter a *lot*, so it could account for what you
> observed (if the pings and pongs were being priorized over the other
> traffic).
> 
> > connections, but I don't see it on two other servers that I have
> > running.
> 
> > NAPI is turned off.
> 
> Turn it on if the server deals with moderate/high traffic (say >
> 100Mbit/s
> or > 1k pps).  But that will not fix the issue you have, I have NAPI
> on here
> and I *think* I can reproduce your findings in a empty gigE to gigEsw
> to
> gigE connection where one of the ends is an e1000.  I will know
> better if I
> have time to check that at work.  The second gigE machine here has a
> crappy,
> PoS NIC (Broadcom crap) that I never managed to drive over 300Mbit/s,
> so it
> could be adding some jitter too.
> 
> -- 
>   "One disk to rule them all, One disk to find them. One disk to
> bring
>   them all and in the darkness grind them. In the Land of Redmond
>   where the shadows lie." -- The Silicon Valley Tarot
>   Henrique Holschuh
> 
> 
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