Date: Thu, 5 Mar 2009 13:32:32 +0300 From: Oleg Bulyzhin <oleg@FreeBSD.org> To: Sebastian Mellmann <sebastian.mellmann@net.t-labs.tu-berlin.de> Cc: freebsd-ipfw@freebsd.org Subject: Re: ipfw (dummynet) adds delay, but not configured to do so Message-ID: <20090305103232.GA19726@lath.rinet.ru> In-Reply-To: <49AED3B1.1060209@net.t-labs.tu-berlin.de> References: <49AED3B1.1060209@net.t-labs.tu-berlin.de>
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On Wed, Mar 04, 2009 at 08:17:05PM +0100, Sebastian Mellmann wrote: > Hi everyone! > > I hope this is the right place to ask. > > I've got a IPFW ruleset that looks like this: > > cmd=ipfw > bottleneck_bandwidth=100Mbit/s > in_if="em0" > > $cmd pipe 500 config bw $bottleneck_bandwidth > $cmd add pipe 500 all from any to any via $in_if > > When I do a simple ping from one machine to another (actually the > FreeBSD machine is between those machines), I can see a delay of ~2ms. > Without any rules/pipes I've got under 1ms delay. > > The question is: > Why do I have such a "high" delay though I didn't configure any "delay" > in my pipe? > Where does this additional millisecond come from (processing delay for > the packet in the pipe?)? > If I configure another rule (or like 10 more rules) that matches the > packet, I can see the delay increasing. > For example a delay of ~20ms, when I configure 10 pipes. > Am I doing something wrong? > > Thanks in advance for any help and please tell me if you need additional > informations (e.g. kernel configuration). > > > Regards, > Sebastian M. > > > _______________________________________________ > freebsd-ipfw@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-ipfw > To unsubscribe, send any mail to "freebsd-ipfw-unsubscribe@freebsd.org" If you have 7.1R or 6.4R setting net.inet.ip.dummynet.io_fast=1 will probably reduce latency. -- Oleg. ================================================================ === Oleg Bulyzhin -- OBUL-RIPN -- OBUL-RIPE -- oleg@rinet.ru === ================================================================
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