Hi Eric, Thanks for the tip. I tried it out on a faster machine, and I observed no such problems. The first machine that produces this problem has a single core 2.8GHz CPU and the second one, which works fine, has a dual core Intel Atom D510, both machines have 2GB of RAM each. I should note that the faster machine also has a better GIgEthernet card. Interestingly, I do not observe any other signs of CPU throttling, such as dropped packets when I see the problem.
Cheers, Veljko 2010/5/24 Eric Blossom <e...@comsec.com>: > On Fri, May 21, 2010 at 02:15:15PM -0700, Veljko Pejovic wrote: >> Hi, >> >> I'm using two USRP2 with XCVR2450s, a week old gnuradio git master and >> Ubuntu 9.10. >> >> A few months ago while using the OFDM code I observed that I tend to >> receive (or send?) packets in groups, although I was sending them >> individually. >> >> Now, I finally isolated the problem. I added a few simple print lines: >> >> "Message inserted in HAVE_HEADER" - whenever a message is enqueued in >> STATE_HAVE_SYNC of ofdm_frame_sink.cc >> >> and >> >> "Message picked up from the queue" - in queue_watcher_thread in >> ofdm.py, every time the message is fetched from the queue. >> >> The output that I expected was: >> >> Message inserted in HAVE_HEADER >> Message picked up from the queue >> Message inserted in HAVE_HEADER >> Message picked up from the queue >> ... >> >> However, I'm getting rather inconsistent output (this is a sample, >> check the attachment for the first few seconds of the output): >> >> Message inserted in HAVE_HEADER >> Message inserted in HAVE_HEADER >> Message inserted in HAVE_HEADER >> Message inserted in HAVE_HEADER >> Message picked up from the queue >> Message picked up from the queue >> Message picked up from the queue >> Message picked up from the queue >> Message inserted in HAVE_HEADER >> Message inserted in HAVE_HEADER >> Message inserted in HAVE_HEADER >> Message inserted in HAVE_HEADER >> Message inserted in HAVE_HEADER >> Message picked up from the queue >> Message picked up from the queue >> Message picked up from the queue >> Message picked up from the queue >> Message picked up from the queue >> >> So, it is definitely the receiver that has problems. It looks as if >> "msg = self.rcvd_pktq.delete_head()" in queue_watcher_thread in >> ofdm.py is not checked frequently enough. Could it be that Python does >> not switch threads fast enough? Note, I do have real time scheduling >> enabled. >> Any ideas on how to get around this? > > Is your machine out of CPU cycles? > If it's not fast enough, it won't keep up. > > Eric > _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
