dummynet, em driver, device polling issues :-((

Gleb Smirnoff glebius at FreeBSD.org
Mon Oct 3 03:45:52 PDT 2005

On Mon, Oct 03, 2005 at 12:31:59PM +0200, Ferdinand Goldmann wrote:
F> Initial observations showed that the system had a very high interrupt load, 
F> most of the times > 50%, and lagged a little bit. Plus, performance-testing 
F> with tcpspray yielded bad results at around 10MB/s, or even worse. So we 
F> tried enabling device polling on the em0 interface. After some testing, we 
F> set HZ=1000 and kern.polling.burst_max: 300. This made things slightly 
F> better, our tcpspray tests now reaching a ~13MB/s throughput.
F> However, now the input errors on the em0 interface were rapidly rising:
F> Name    Mtu Network       Address              Ipkts Ierrs    Opkts Oerrs  
F> Coll
F> em0    1500 <Link#3>      00:0e:0c:6d:4c:f9 3738461290 8605788 3613603979   
F> 0 0
F> So for now, the polling is disabled again.

All I can say: I have faced this problem, too. :( This is not problem in
polling, but in em.

Totus tuus, Glebius.

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