fsset@neptune.lerc.nasa.gov (Scott E. Townsend) (06/07/90)
I've got a question regarding intermittent system hangs. A 'system hang' means that all apparent activity on the Personal Iris monitor freezes, including the mouse cursor. Here's my setup: 1. There are two ordinary user programs communicating with a remote system via shared memory in the remote system's VME rack. One program loads & monitors the remote system's execution, the other program provides a 'real-time' display of remote data via a 3D surface plot. 2. The Personal Iris's VME adaptor is connected to the remote system's VME rack via a VME repeater, the model 2000 repeater from HVE Engineering Inc. 3. The remote system's shared memory is mapped via the mmap() call: cube_data = mmap(0, MEMORY_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, mem_fd, (VME_A24SBASE | 0XA0000000) + CUBE_ADDR); where MEMORY_SIZE is 1 Meg and CUBE_ADDR is set at 4 Meg. (This is for the surface plotter, a similar call is made for the loader/monitor, mapping 4 Meg starting at 0) Here's my symptoms: 1. The system usually runs fine, but some days (phase of the moon?) it will hang after running for 30 seconds or so. (Enough time to record 5-10 plots) This is semi-repeatable. 2. It seems to hang only if the surface plotter is running. The surface plotter is just a simple tmesh algorithm, nothing fancy, with a mesh size of 34 x 34 typically. Note that when the system is using the surface plotter there is significantly more communication across the VME repeater. Also, I can't run just the plotter, I need the loader/monitor to get things to run. 3. There is no console output if I have a console running on the Iris display. 4. When the system hangs, the remote system still runs until its communications time-out waiting for the frozen Iris. So now the questions: 1. Has anyone had any experience with hanging repeaters on the Iris's VME adaptor? 2. Under what conditions could a normal user program freeze the system? I would think a programming error would simply cause a segmentation fault or somthing similar. 3 Any suggestions on how I could debug this thing? I have access to a VME bus monitor, but its triggering facilities are a bit primitive. Thanks for any and all help you can provide. -- ------------------------------------------------------------------------ Scott Townsend | Phone: 216-433-8101 NASA Lewis Research Center | Mail Stop: 5-11 Cleveland, Ohio 44135 | Email: fsset@neptune.lerc.nasa.gov ------------------------------------------------------------------------