floating point operations

James Healy jhealy at swin.edu.au
Wed Oct 31 17:31:42 PDT 2007


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hackers,

We've been making experimental changes to FreeBSD's TCP congestion
control code, and we used a few floating point operations initially in
our prototype.

We've since gone back and converted all but one of the operations to
fixed point maths in following the no-flops-in-kernel mantra.

The remaining op is not easily converted to fixed point math, and we're
wondering what impact a single flop on the receipt of each ACK will
have. We don't have a strong understanding of the amount of overhead
involved in executing a flop instead of an int op on modern hardware.

regards

James Healy
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