I have run into this problem on the Beagleboard ... here's my explanation for
what I think is happening and the fix. What's happening is GNU Radio is trying
to run as a real time thread which if you're root or you've given your Linux
username permission to have rtprio privileges but for some reason I also ran
into the problem where I can't get realtime scheduling privileges.
The parametes of interest to fix this problem are
cat /proc/sys/kernel/sched_rt_runtime_us
output = 950000
cat /proc/sys/kernel/sched_rt_period_us
output = 1000000
now sched_rt_period_us controls the scheduling period in your processor and
sched_rt_runtime_us controls how much of that period is reserved for realtime
processing. When you read the associated driver documentation it says to
disable this segmenting for the realtime period partitioning you need to set
sched_rt_runtime_us to -1 or you can completely disable this feature in your
kernel by "make menuconfig" in your kernel driver directory ... my preference
is not to mess with drivers so I set it to -1 with
echo -1 > sched_rt_runtime_us
now when you run
cat /proc/sys/kernel/sched_rt_runtime_us
output = -1
Now you should be able to use realtime scheduling in GNU Radio. I'm not sure
if this is a good fix because it might give background processes realtime
privileges which would defeat the purpose of the realtime designation ... for
me I'm running console Linux on the Beagleboard so it's an acceptable solution.
As an alternative approach you might try to use the Linux "nice" and "renice"
programs to tweak thread priority but I personally wans't successful with this
approach.
al fayez
-----Original Message-----
From: Anoth <francois.darr...@gmail.com>
To: Discuss-gnuradio <Discuss-gnuradio@gnu.org>
Sent: Thu, Feb 24, 2011 6:59 pm
Subject: [Discuss-gnuradio] FM Receiver
Hi
I am using an USRP N210 with GNU radio, UHD and GRC on Ubuntu 10.10. I have
connected a WBX daughterboard to the USRP. I want to receive and, of course,
listen the radio thanks to this system. I have built a flow graph and when I
execute it, I only heard noise and can see this message in the terminal :
linux; GNU C++ version 4.4.5; Boost_104200; UHD_002.20110206225409.aea6ac1
>>> gr_fir_fff: using SSE
Current recv sock buff size: 50000000 bytes
Warning:
error in pthread_setschedparam
Failed to set thread priority 0.5 (realtime):
Performance may be negatively affected.
See the general application notes.
Warning:
error in pthread_setschedparam
Failed to set thread priority 0.5 (realtime):
Performance may be negatively affected.
See the general application notes.
mboard0 MIMO master
Warning:
error in pthread_setschedparam
Failed to set thread priority 0.5 (realtime):
Performance may be negatively affected.
See the general application notes.
>>> gr_fir_ccc: using SSE
aUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaUaU
I have looked on the internet and tried different things but nothing has
changed. Could someone give me an hand to solve with problem ?
Thank you very much,
Francois
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