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Date: Tue, 4 Jan 2011 14:03:52 -0600
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From: Lin Xue <lxue2@tigers.lsu.edu>
To: freebsd-ipfw@freebsd.org
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Subject: RED SCALE problem?
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Hi all,

I am trying to do some test on RED for different parameters(like
min/max threshold, probability..), but find there might be some
problem with SCALE of RED.

In ip_dummynet.h

RED SCALE is defined as:
#define SCALE_RED               16
#define SCALE(x)                ( (x) << SCALE_RED )


And in ip_dummynet.c, the min and max threshold is scaled below:
/* Now doing stuff that was in kerneland */
fs->min_th = SCALE(fs->fs.min_th);
fs->max_th = SCALE(fs->fs.max_th);

In that case, the min and max threshold will only support up to 16 bit
(0-65K+) ? otherwise the higher bits will be dropped, because min_th
and min_th all are int.

Thank you!