polling(4) rocks!

[Charles Swiger]

On Nov 17, 2004, at 1:52 PM, Eugene Grosbein wrote:
> On Wed, Nov 17, 2004 at 09:13:51PM +0300, Yar Tikhiy wrote:
> [ ...praise of polling(4)... ]
> Does polling(4) increase latency? It is very imortant for router
> that handles lots of RTP (VoIP) traffic.

Using polling does increase the latency of the traffic, slightly: if 
you follow the recommended configuration and set HZ=1000 or so, the 
added latency typically ends up being around 1ms.

That's not enough to affect VoIP significantly.  I've got 12 VoIP phone 
lines going through a FreeBSD 4.10 firewall using polling(4) over a T1 
now.  The firewall box is a Dell P3/400MHz or so using fxp and a 
quad-port card using the DEC 21x4x chipset.

-- 
-Chuck