Latency from Cyclic Test in NUC

[Snoopy8]

Bear in mind if you're using cyclictest from within the Snakeoil App, 10x difference is pretty insignificant. Divide the numbers by 1000 and then compare the non-decimals numbers to get a rough idea.

I believe it is time to refresh Cyclictest within the SnakeOil App. Running App while playing Mpd on my 4 CPU Intel NUC with CPUSets enabled and with RT kernel:

# /dev/cpu_dma_latency set to 0us
T: 0 ( 8756) P:80 I:10000 C: 10000 Min: 1691 Act: 1893 Avg: 1911 Max: 4641
T: 1 ( 8757) P:80 I:10500 C: 9525 Min: 1805 Act: 1963 Avg: 2193 Max: 19971

Running my own:
sudo cyclictest -t4 -p 90 -N -s -i 10000 -l 10000 -q
# /dev/cpu_dma_latency set to 0us
T: 0 ( 8993) P:90 I:10000 C: 10000 Min: 1990 Act: 2210 Avg: 2206 Max: 6470
T: 1 ( 8994) P:90 I:10500 C: 9526 Min: 2081 Act: 2779 Avg: 2338 Max: 4752
T: 2 ( 8995) P:90 I:11000 C: 9093 Min: 2072 Act: 3515 Avg: 2372 Max: 5896
T: 3 ( 8996) P:90 I:11500 C: 8698 Min: 2252 Act: 3188 Avg: 2602 Max: 5586

Comments & questions:

• App results can be misleading for those new to Cyclictest! 
  
• Do realise that SnakeOil App is old (and did read a very old thread and the debates!)
  
• Cyclictest has its limitations but probably easiest tool to run?  I understand that the most relevant number is the Max latency, and this should be in comments after App has run.
  
• Add also in comments that App should be run when playing music, otherwise results are not relevant.
  
• App should take into account number of CPUs.  Not sure whether App should run on a particular CPU?
  
• How many times should Cyclictest be run?  Each run is a snapshot of the system at that time.  While my Max results are typically 5 to 7 microseconds, I can get 9 to 10 microseconds in about 1 in 10 runs. 
  
• This raises the question of whether a histogram of say 10 to 20 runs, makes more sense, but then, how many people are prepared to run the App for an extended period?
  
• Wiki should be updated with info from this discussion.  And it should include the comment that the results are not a contest between each person's setup!