Excessive "intr" CPU usage caused by Dummynet

Patrick Tracanelli eksffa at freebsdbrasil.com.br
Wed Feb 23 15:52:23 UTC 2011


Hello Gentlemen,

What may cause dummynet to exaust CPU cycles on kernel "intr" requests?

I am facing a situation where "top -S" shows something like that:

 12 root       13 -60    -     0K   104K WAIT    0 744:58 82.50% intr

And when I get into >95% intr cpu usage, packets on dummynet raise their latency a lot, slowing down everything (pipe or queue).

Queue sizes are ajusted according to pipe bandwidth, using a sort of rule where queue in bytes is equal to pipe width divided by 8 or by 10.

Thank you.

--
Patrick Tracanelli

FreeBSD Brasil LTDA.
Tel.: (31) 3516-0800
316601 at sip.freebsdbrasil.com.br
http://www.freebsdbrasil.com.br
"Long live Hanin Elias, Kim Deal!"



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