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Date:      Thu, 11 Aug 2005 12:59:13 -0400
From:      Chuck Swiger <>
To:        Volodya Pelekh <>
Subject:   Re: Problem with dummynet
Message-ID:  <>
In-Reply-To: <>
References:  <> <> <>

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Volodya Pelekh wrote:
> Yes it set at default value
> sysctl kern.clockrate
> kern.clockrate: { hz = 100, tick = 10000, profhz = 1024, stathz = 128 }
> but in freebsd 4.5, 5.3 in my network this set in HZ 100 too, and i
> have not this problem on those computers

How much of a difference changing HZ makes may depend on a lot of things such 
as whether you are using device polling, etc, but if you care about reducing 
the latency observed by network stats to below 10 ms, adding:

kern.hz="1000" /boot/loader.conf and rebooting is definitely worth the try.  As the 
manpage for dummynet itself says:

     Generally, the following options are required:

            options IPFIREWALL
            options DUMMYNET
            options HZ=1000         # strongly recommended

      Additionally, one may want to increase the number of mbuf clusters (used
      to store network packets) according to the sum of the bandwidth-delay
      products and queue sizes of all configured pipes.

Also, you ought to upgrade that 4.5 system to 4.11 if you can, there are some 
significant security issues which have been issued between the two, BTW.


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