Hi all,
Eric, thank you for your reply. I ran the tunnel.py with the username "useSDR" in group usrp and added @usrp - rtprio 50 in the /etc/security/limits.conf. gr.enable_realtime_scheduling() is in the orignial tunnel.py file. However, I keep get an error as following: File "tunnel_original.py", line 78, in open_tun_interface tun = os.open(tun_device_filename, os.O_RDWR) OSError: [Errno 13] Permission denied: '/dev/net/tun' I think it is because I did not set the authority right on my linux system. I have tried many ways. I even set "root" in the group usrp. The RTT of tunnel.py is still about 30 ms. /etc/group root:x:0:root,useSDR usrp:x:501:useSDR,root Does anyone have any idea what's wrong? Thank you, Jane --- On Wed, 8/12/09, Eric Blossom <e...@comsec.com> wrote: From: Eric Blossom <e...@comsec.com> Subject: Re: [Discuss-gnuradio] RTOS and GNU Radio To: "Jane Chen" <janechen_1...@yahoo.com> Cc: discuss-gnuradio@gnu.org Date: Wednesday, August 12, 2009, 6:20 PM On Wed, Aug 12, 2009 at 11:05:19AM -0700, Jane Chen wrote: > Hi all, > > I ran the tunnel.py, which is one of the gnuradio-examples, on two > PCs (fedora 9 (kernel: 2.6.27), GNU Radio 3.2 and Intel Pentium > D). The RTT is about 30ms. I read the paper "Enabling MAC Protocol > Implementations on Software-Defined Radios" which is written by > George Nychis and found that GNU radio needs 25ms in the user space > in the example. I am wondering if I can use the real time OS to > reduce the latency in the user space. However, I don't see any RTOS > in the build guide on the GNU Radio Wiki > (http://gnuradio.org/trac/wiki/BuildGuide ) . Does anyone know about > if RTOS can reduce the RTT of tunnel.py to less than 1ms? Before you go the RTOS route, I suggest that you simply try enabling real-time scheduling on Linux. Be sure you're in group usrp, then add this line to /etc/security/limits.conf: @usrp - rtprio 50 Then in your GR program add a call to: gr.enable_realtime_scheduling() There are several examples that do this. Eric
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