Transmitter's bizarre behavior on 64 bit workstation


I found a puzzling fact about running GNU Radio on the 64-bit Lenovo
workstation D20.

Basically, the maximum packet size (payload at the transmitter side in
the must be less than or equal to 221. Below this size,
packets from the workstation can be correctly received by either a
laptop or another workstation; above this size, no packet can be
received correctly on either a laptop or another workstation. I was
using 500kb data rate and GMSK modulations.

The same code works perfectly on a laptop as the transmitter, no matter
the receiver side is on a laptop or a workstation.

At first, I thought it might be a result of the quad core (8 CPUs)
architecture. So I disable 3 cores and only one core was left. However,
I got the same result.

Also, the CPU usage for a transmitter doesn’t make sense to me either.
It was above 90% on the workstation (2 Intel Xeon X5550 cpus at 2.67
GHz). However it was only around 35% on the laptops (2 Intel T9550 CPUs
at 2.66GHz).

I could not understand what might be the problem.