Re: [Discuss-gnuradio] Unexplained out-of-sequence packets...

On Wed, May 12, 2010 at 04:34:36PM +0930, Ian Holland wrote:
> Hi Eric
>
> It seems this has not fixed the problem. Does anyone have any other
> suggestions as to the possible cause? Note, I also found power cycling
> the USRP2 can sometimes avoid the same problem.
>
> Ian.

Ian,

I still suspect something in your host setup.

Is the USRP2 connected directly to the host or does it go through a
switch? If there's a switch in the path, please remove it.

Note that the cpu throttling / clock scaling hypothesis would explain
why it works better under higher load than lower load. Are you sure
that your cpu isn't being throttled?

When you're seeing the problem, try:

$ grep 'cpu MHz' /proc/cpuinfo

and see if all cores are running at full speed.

E.g.,

Idling laptop (throttled back from 1.83GHz):

[eb@cyan ~]$ grep 'cpu MHz' /proc/cpuinfo
cpu MHz : 1000.000
cpu MHz : 1000.000

Server with cpu scaling disabled:

[eb@octo swig]$ grep 'cpu MHz' /proc/cpuinfo
cpu MHz : 2999.488
cpu MHz : 2999.488
cpu MHz : 2999.488
cpu MHz : 2999.488
cpu MHz : 2999.488
cpu MHz : 2999.488
cpu MHz : 2999.488
cpu MHz : 2999.488

Eric

> -----Original Message-----
> From: discuss-gnuradio-bounces+ian.holland=rlmgroup.com.au@gnu.org
> [mailto:discuss-gnuradio-bounces+ian.holland=rlmgroup.com.au@gnu.org] On
> Behalf Of Ian Holland
> Sent: Tuesday, 11 May 2010 11:14 AM
> To: Eric Blossom
> Cc: discuss-gnuradio@gnu.org
> Subject: RE: [Discuss-gnuradio] Unexplained out-of-sequence packets...
>
> Thanks Eric
>
> I checked the power management preferences and couldn't see anything
> about CPU throttling, though I did verify it would never go to sleep
> after inactivity. Then, I found some info on
> http://blog.mpathirage.com/2009/10/04/how-to-disable-dynamic-frequency-s
> calingcpu-throttling-in-ubuntu-jaunty9-04/ to disable the CPU throttling
> (I know I am using 9.10, not 9.04, but I imagine it should be the same).
>
> After rebooting (only once), I haven't yet seen the problem again.
> Unfortunately, given the seemingly random nature of the problem, I guess
> it is a wait-and-see matter as to whether it ever does resurface.
>
> Cheers
>
> Ian.

_______________________________________________
Discuss-gnuradio mailing list
Discuss-gnuradio@gnu.org
http://lists.gnu.org/mailman/listinfo/discuss-gnuradio