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Date:      Thu, 11 Jul 2002 22:54:52 +0200
From:      Thierry Herbelot <thierry@herbelot.com>
To:        Matthew Dillon <dillon@apollo.backplane.com>
Cc:        freebsd-stable@FreeBSD.ORG
Subject:   Re: tuning(7) request was: Re: Performance boost with kernel options in  FBSD 4.6
Message-ID:  <3D2DF09C.B553DE07@herbelot.com>
References:  <20020710104730.L10343-100000@klima.physik.uni-mainz.de> <04a601c228dc$c6dbb980$681663cf@icarz.com> <200207111930.g6BJUX5m096974@apollo.backplane.com>

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Matthew Dillon wrote:
> 
>     An increased switching rate (increasing HZ) may be useful in the above
>     situation.  Still, I would not recommend increasing Hz above 500 (2ms).
>     10000 (100uS) is just plain insane.
> 

from actual experience, any p-III with a clock rate above 500MHz (that
is, any recent CPU) can sustain Hz=5000, which I used to run
trafific-shaped packet blasters (admittedly a narrow focus ...) with
very good results (better than special-purpose test boxes).

As is said in the dummynet man page, FreeBSD can be a very good traffic
shaper, if the userland scheduling rate is high enough (will it be the
same with threads in -current, with KSE ?).

many of my machines run with GENERIC and kern.hz=1000 in
/boot/loader.conf
(I still have to look if NTIMECOUNTER is upped in the same porportion :
USTL !)

	TfH

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