We have all the sensors and the data system running in the staging area. We've added one Licor 7500 to what was last on the tower, for a total of 4 Licors. The data cables, and Licor power cables are different however, since the originals were left on the tower.

After setting it up, I increased the 4 Licor 7500s from 10 samples/sec at 9600 baud to 20 samples/sec at 19200 baud.

The spurious interrupts are happening, sometimes spiking to above 100:

Jun 28 21:27:02 manitou kernel: viper_irq_handler: irq=2 spurious= 326001, #/sec=102   
Jun 28 21:27:21 manitou kernel: viper_irq_handler: irq=2 spurious= 328001, #/sec=109   
Jun 28 21:29:06 manitou kernel: viper_irq_handler: irq=2 spurious= 338001, #/sec=102   
Jun 28 21:29:46 manitou kernel: viper_irq_handler: irq=2 spurious= 342001, #/sec=106   
Jun 28 21:29:56 manitou kernel: viper_irq_handler: irq=2 spurious= 343001, #/sec=102   
Jun 28 21:30:38 manitou kernel: viper_irq_handler: irq=2 spurious= 347001, #/sec=103       
Jun 28 21:30:48 manitou kernel: viper_irq_handler: irq=2 spurious= 348001, #/sec=101                                          
Jun 28 21:31:28 manitou kernel: viper_irq_handler: irq=2 spurious= 352001, #/sec=111
Jun 28 21:31:58 manitou kernel: viper_irq_handler: irq=2 spurious= 355001, #/sec=104           

root@manitou root# uptime
 21:44:36 up  1:43,  1 user,  load average: 0.16, 0.11, 0.09

The kernel issues a "spurious" message when they occur more often than 100/sec. The system came up at 21:44 - 1:43 = 20:01. At the time of the last message above, the system had been up for 1 hour 31 minutes. 355001 interrupts in 1 hour 31 minutes averages to 65/sec.

The above test is with the same kernel (2.6.16.28-arcom1-2-viper #1 PREEMPT Wed Sep 16 17:04:19 MDT 2009) and CPU (viper 4) as was deployed on the tower. 

manitou:/dev/ttyS9           1     20        14 2012 06 28 23:13:12.975  06 28 23:13:26.005    1.00  0.938  1.043   19   19
manitou:/var/tmp/gps_pty0    1     30        29 2012 06 28 23:13:12.574  06 28 23:13:26.574    2.00  0.154  0.882   72   73
manitou:/dev/ttyS1           1    100       285 2012 06 28 23:13:12.624  06 28 23:13:26.820   20.01  0.046  0.054   12   12
manitou:/dev/ttyS5           1    120        15 2012 06 28 23:13:12.893  06 28 23:13:26.489    1.03  0.965  0.979   30   30
manitou:/dev/ttyS6           1    200       285 2012 06 28 23:13:12.654  06 28 23:13:26.852   20.00  0.044  0.058   12   12
manitou:/dev/ttyS7           1    210       285 2012 06 28 23:13:12.619  06 28 23:13:26.814   20.01  0.042  0.059   56   56
manitou:/dev/ttyS8           1    220        14 2012 06 28 23:13:13.516  06 28 23:13:26.256    1.02  0.974  0.986   29   29
manitou:/dev/ttyS10          1    300       285 2012 06 28 23:13:12.652  06 28 23:13:26.854   20.00  0.041  0.061   12   12
manitou:/dev/ttyS11          1    310       285 2012 06 28 23:13:12.621  06 28 23:13:26.825   19.99  0.045  0.056   49   49
manitou:/dev/ttyS12          1    320        15 2012 06 28 23:13:13.098  06 28 23:13:26.775    1.02  0.971  0.986   29   29
manitou:/dev/ttyS19          1    330         3 2012 06 28 23:13:10.785  06 28 23:13:20.787    0.20  5.000  5.002   56   56
manitou:/dev/ttyS13          1    400       285 2012 06 28 23:13:12.658  06 28 23:13:26.858   20.00  0.046  0.054   12   12
manitou:/dev/ttyS14          1    410       286 2012 06 28 23:13:12.593  06 28 23:13:26.845   20.00  0.047  0.052   49   49
manitou:/dev/ttyS15          1    420        14 2012 06 28 23:13:13.374  06 28 23:13:26.024    1.03  0.969  0.980   30   30
manitou:/dev/ttyS20          1    500       286 2012 06 28 23:13:12.622  06 28 23:13:26.869   20.00  0.047  0.053   12   12
manitou:/dev/ttyS17          1    510       285 2012 06 28 23:13:12.619  06 28 23:13:26.824   19.99  0.042  0.058   49   49
manitou:/dev/ttyS18          1    520        14 2012 06 28 23:13:13.284  06 28 23:13:25.990    1.02  0.970  0.984   30   30