Re: Intel Pro/1000 MT and strange ping RTTs
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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