Date: Wed, 4 Mar 2009 22:14:09 +0100 From: Luigi Rizzo <rizzo@iet.unipi.it> 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: <20090304211409.GA29824@onelab2.iet.unipi.it> In-Reply-To: <49AEED31.8060801@net.t-labs.tu-berlin.de> References: <49AED3B1.1060209@net.t-labs.tu-berlin.de> <20090304210017.GA29615@onelab2.iet.unipi.it> <49AEED31.8060801@net.t-labs.tu-berlin.de>
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On Wed, Mar 04, 2009 at 10:05:53PM +0100, Sebastian Mellmann wrote: > > > 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 > >> > > > > the delay that a packet experiences corresponds to len/bandwidth, > > often rounded up to the next clock tick (1ms is the default). > > You get one delay inbound, one delay outbound, so that's 2ms. > > > > > Is there any chance to change this clock tick to a lower value? > I think it's the 'HZ=' option in the kernel config isn't it? yes. i believe there is a tunable (so you don't need to rebuild the kernel) but i do not remember exactly which one. cheers luigi
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