Transmitter's bizarre behavior on 64 bit workstation

Eric,

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 benchmark_tx.py) 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.

Andrew