On Thu, Nov 18, 2004 at 01:52:49AM +0700, Eugene Grosbein wrote: > On Wed, Nov 17, 2004 at 09:13:51PM +0300, Yar Tikhiy wrote: > > > The router box is a 1.4GHz Celeron PC with an fxp(4) interface split > > across a dozen of vlans. There is nothing special about its setup > > except for ~250 rules loaded into ipfw2. It is running 4.10-RELEASE. > > Without polling, it was able to switch full 10Mbytes/sec of traffic > > (~9kpps), but that took from 50 to 70% CPU time spent in interrupts. > > With polling on, interrupt time never exceeds 5% and it stays as low > > as 1-2% on average even when traffic is that high. > > Does polling(4) increase latency? It is very imortant for router > that handles lots of RTP (VoIP) traffic.
If you have a box doing lot of traffic in packets per second, enabling polling with HZ=2000 +/- will actually *decrease* latency due to far lower overhead instead of handling all those interrupts/sec. On a low-to-no traffic box, it's probably not worth it, however use your own judgement. Either way, the amount of latency polling(4) adds even in HZ=100 is very low enough (1 ms or less. if using 2000 or so, there is not much noticeable latency in line of microseconds) to affect most applications. -J -- James Jun TowardEX Technologies, Inc. Technical Lead IPv4 and Native IPv6 Colocation, Bandwidth, [EMAIL PROTECTED] and Web Hosting Services in the Metro Boston area cell: 1(978)-394-2867 web: http://www.towardex.com , noc: www.twdx.net _______________________________________________ [EMAIL PROTECTED] mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-net To unsubscribe, send any mail to "[EMAIL PROTECTED]"
