Josh,

I’ve upgraded to 3.5rc0. The same thing happened. I got some more

details:

## When I ran benchmark_tx on 1 machine, at low bitrate (0.1Mbps or 0.2MSps

I’m using bpsk) the CPU utilization is roughly 9%.

But the receiver, running benchmark_rx showed 110% CPU utilization.

If I up the bitrate to 1Mbps,

the transmitter showed 90% CPU utilization so it scaled linearly.

the receiver starts out showing 110% CPU utilization, so I guess it

processed noise also, which makes sense because there’s no

carrier-sense.

It did nothing for a while (~30 sec), then started showing correct

receptions. Until a point, it started to show overrun. Here’s part of

the

output on the receiver:

ok = True pktno = 859 n_rcvd = 859 n_right = 859

ok = True pktno = 860 n_rcvd = 860 n_right = 860

ok = True pktno = 861 n_rcvd = 861 n_right = 861

ok = True pktno = 862 n_rcvd = 862 n_right = 862

ok = True pktno = 863 n_rcvd = 863 n_right = 863

ok = True pktno = 864 n_rcvd = 864 n_right = 864

ok = True pktno = 865 n_rcvd = 865 n_right = 865

ok = True pktno = 866 n_rcvd = 866 n_right = 866

ok = True pktno = 867 n_rcvd = 867 n_right = 867

Ook = True pktno = 868 n_rcvd = 868 n_right = 868

OOOok = False pktno = 869 n_rcvd = 869 n_right = 868

OOOOOOOok = False pktno = 879 n_rcvd = 870 n_right = 868

OOOOOOOOOok = False pktno = 902 n_rcvd = 871 n_right = 868

OOOOOOOok = False pktno = 914 n_rcvd = 872 n_right = 868

OOOOOOOOok = False pktno = 929 n_rcvd = 873 n_right = 868

OOOOOOOOOOOok = False pktno = 950 n_rcvd = 874 n_right = 868

OOOOOOOOOOOOOOOok = False pktno = 970 n_rcvd = 875 n_right = 868

OOOOOOOOOOOOOOOOOOOOOOOOOOok = False pktno = 983 n_rcvd = 876

n_right

= 868

OOOOOOOok = False pktno = 987 n_rcvd = 877 n_right = 868

OOOOOOok = False pktno = 990 n_rcvd = 878 n_right = 868

OOOOOOok = False pktno = 993 n_rcvd = 879 n_right = 868

OOOOOOok = False pktno = 996 n_rcvd = 880 n_right = 868

Another thing is when I started the transmitter first, then the receiver

started to show received samples right away. If I started the receiver

first, then it had the 30 sec delay mentioned above.

Before I used to run these code on the old gnuradio version (3.2.2) and

Ethernet driver and didn’t have this problem. Could this be related to

the

new implementation of gnuradio and/or the UHD driver? Or is there any

other

possible explanation?

Thank you,

Johnny