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Date:      Tue, 20 Aug 2002 00:38:16 -0700
From:      Luigi Rizzo <rizzo@icir.org>
To:        Carlos Carnero <zopewiz@yahoo.com>
Cc:        freebsd-net@FreeBSD.ORG
Subject:   Re: Bandwidth throttling with dummynet(4)
Message-ID:  <20020820003816.A44103@iguana.icir.org>
In-Reply-To: <20020820013634.3113.qmail@web21410.mail.yahoo.com>; from zopewiz@yahoo.com on Mon, Aug 19, 2002 at 06:36:34PM -0700
References:  <20020819154141.A41050@iguana.icir.org> <20020820013634.3113.qmail@web21410.mail.yahoo.com>

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On Mon, Aug 19, 2002 at 06:36:34PM -0700, Carlos Carnero wrote:
> Hello,
> 
> > dummynet pipes use timers heavily, and i suspect
> > that the timer granularity in vmware might not be
> > as good as you would want
> 
> yes, you're right. I changed some thing though:
> increased HZ in the kernel config from 1000 to 1500;
> and currently I'm running the virtual machine at a
> higher priority. Luckily I have a very fast host with
> lots of RAM.

1500 vs 1000 won't help much -- events will be scheduled with the
host system's timer granularity, which might well be low (100-128
or so for NT). Secondly, you are running two virtual machines, so
i believe they will compete for resources causing the timing
to be flaky.

Anyways, on real boxes dummynet does work as expected at those rates.

	cheers
	luigi
> 
> I'll play more with the slots, but those speeds (~
> 5KByte/s) are the ones that the real thing will use.
> I'm building a router for a friend that has to share a
> 256KBit/s link among 100 people :o
> 
> I know that VMware is not exactly the best thing to
> test dummynet, but right now I have no other choice.
> It's an experience anyway.

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