Once started pcm fails to monitor UPI traffic after some time

[simonhf]

If I run pcm then it always successfully initially starts dishing up UPI stats for the firsts seconds -- sometimes many seconds -- of operation. But always eventually stops working. Why?

Example run which it stops working after a few seconds:

$ sudo /usr/sbin/pcm 2>/dev/null | egrep --line-buffered "Total UPI " | perl -lane '$cc .= sprintf qq[%s ], $_; if(m~non-data~){ printf qq[%s\n], $cc; undef $cc; }'
Total UPI incoming data traffic:  233 M     UPI data traffic/Memory controller traffic: 0.30 Total UPI outgoing data and non-data traffic:  834 M 
Total UPI incoming data traffic:  155 M     UPI data traffic/Memory controller traffic: 0.26 Total UPI outgoing data and non-data traffic:  554 M 
Total UPI incoming data traffic:  152 M     UPI data traffic/Memory controller traffic: 0.25 Total UPI outgoing data and non-data traffic:  539 M 
Total UPI incoming data traffic:  171 M     UPI data traffic/Memory controller traffic: 0.22 Total UPI outgoing data and non-data traffic:  642 M 
Total UPI incoming data traffic:  804 M     UPI data traffic/Memory controller traffic: 0.33 Total UPI outgoing data and non-data traffic: 2753 M 
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: 0.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:  246 M     UPI data traffic/Memory controller traffic: 0.26 Total UPI outgoing data and non-data traffic:  967 M 
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
^C

Example run which it stops working after many seconds and never really recovers:

$ sudo /usr/sbin/pcm 2>/dev/null | egrep --line-buffered "Total UPI " | perl -lane '$cc .= sprintf qq[%s ], $_; if(m~non-data~){ printf qq[%s\n], $cc; undef $cc; }'
Total UPI incoming data traffic:  245 M     UPI data traffic/Memory controller traffic: 0.30 Total UPI outgoing data and non-data traffic:  850 M 
Total UPI incoming data traffic:  153 M     UPI data traffic/Memory controller traffic: 0.25 Total UPI outgoing data and non-data traffic:  538 M 
Total UPI incoming data traffic:  159 M     UPI data traffic/Memory controller traffic: 0.24 Total UPI outgoing data and non-data traffic:  594 M 
Total UPI incoming data traffic:  223 M     UPI data traffic/Memory controller traffic: 0.22 Total UPI outgoing data and non-data traffic:  867 M 
Total UPI incoming data traffic:  107 M     UPI data traffic/Memory controller traffic: 0.22 Total UPI outgoing data and non-data traffic:  388 M 
Total UPI incoming data traffic:  187 M     UPI data traffic/Memory controller traffic: 0.24 Total UPI outgoing data and non-data traffic:  672 M 
Total UPI incoming data traffic:  242 M     UPI data traffic/Memory controller traffic: 0.28 Total UPI outgoing data and non-data traffic:  879 M 
Total UPI incoming data traffic:  100 M     UPI data traffic/Memory controller traffic: 0.21 Total UPI outgoing data and non-data traffic:  369 M 
Total UPI incoming data traffic:   95 M     UPI data traffic/Memory controller traffic: 0.20 Total UPI outgoing data and non-data traffic:  348 M 
Total UPI incoming data traffic:  125 M     UPI data traffic/Memory controller traffic: 0.22 Total UPI outgoing data and non-data traffic:  462 M 
Total UPI incoming data traffic:  150 M     UPI data traffic/Memory controller traffic: 0.25 Total UPI outgoing data and non-data traffic:  534 M 
Total UPI incoming data traffic:  138 M     UPI data traffic/Memory controller traffic: 0.23 Total UPI outgoing data and non-data traffic:  494 M 
Total UPI incoming data traffic:  145 M     UPI data traffic/Memory controller traffic: 0.21 Total UPI outgoing data and non-data traffic:  541 M 
Total UPI incoming data traffic:  206 M     UPI data traffic/Memory controller traffic: 0.25 Total UPI outgoing data and non-data traffic:  759 M 
Total UPI incoming data traffic:  156 M     UPI data traffic/Memory controller traffic: 0.21 Total UPI outgoing data and non-data traffic:  588 M 
Total UPI incoming data traffic:  157 M     UPI data traffic/Memory controller traffic: 0.25 Total UPI outgoing data and non-data traffic:  558 M 
Total UPI incoming data traffic:  270 M     UPI data traffic/Memory controller traffic: 0.26 Total UPI outgoing data and non-data traffic:  988 M 
Total UPI incoming data traffic:  139 M     UPI data traffic/Memory controller traffic: 0.23 Total UPI outgoing data and non-data traffic:  502 M 
Total UPI incoming data traffic:  105 M     UPI data traffic/Memory controller traffic: 0.20 Total UPI outgoing data and non-data traffic:  383 M 
Total UPI incoming data traffic:  812 M     UPI data traffic/Memory controller traffic: 0.34 Total UPI outgoing data and non-data traffic: 2740 M 
Total UPI incoming data traffic:  291 M     UPI data traffic/Memory controller traffic: 0.29 Total UPI outgoing data and non-data traffic: 1033 M 
Total UPI incoming data traffic:  135 M     UPI data traffic/Memory controller traffic: 0.24 Total UPI outgoing data and non-data traffic:  492 M 
Total UPI incoming data traffic:  164 M     UPI data traffic/Memory controller traffic: 0.25 Total UPI outgoing data and non-data traffic:  603 M 
Total UPI incoming data traffic:  135 M     UPI data traffic/Memory controller traffic: 0.24 Total UPI outgoing data and non-data traffic:  495 M 
Total UPI incoming data traffic:  217 M     UPI data traffic/Memory controller traffic: 0.22 Total UPI outgoing data and non-data traffic:  864 M 
Total UPI incoming data traffic:  275 M     UPI data traffic/Memory controller traffic: 0.26 Total UPI outgoing data and non-data traffic: 1018 M 
Total UPI incoming data traffic:  246 M     UPI data traffic/Memory controller traffic: 0.30 Total UPI outgoing data and non-data traffic:  880 M 
Total UPI incoming data traffic:  183 M     UPI data traffic/Memory controller traffic: 0.25 Total UPI outgoing data and non-data traffic:  654 M 
Total UPI incoming data traffic:  130 M     UPI data traffic/Memory controller traffic: 0.22 Total UPI outgoing data and non-data traffic:  466 M 
Total UPI incoming data traffic:  139 M     UPI data traffic/Memory controller traffic: 0.23 Total UPI outgoing data and non-data traffic:  511 M 
Total UPI incoming data traffic:  229 M     UPI data traffic/Memory controller traffic: 0.30 Total UPI outgoing data and non-data traffic:  775 M 
Total UPI incoming data traffic:  154 M     UPI data traffic/Memory controller traffic: 0.23 Total UPI outgoing data and non-data traffic:  548 M 
Total UPI incoming data traffic:  175 M     UPI data traffic/Memory controller traffic: 0.25 Total UPI outgoing data and non-data traffic:  624 M 
Total UPI incoming data traffic:  202 M     UPI data traffic/Memory controller traffic: 0.23 Total UPI outgoing data and non-data traffic:  780 M 
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: 0.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic: 1781 M     UPI data traffic/Memory controller traffic: 0.37 Total UPI outgoing data and non-data traffic: 5065 M 
Total UPI incoming data traffic:  188 M     UPI data traffic/Memory controller traffic: 0.36 Total UPI outgoing data and non-data traffic:  673 M 
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: 0.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic: 1070 M     UPI data traffic/Memory controller traffic: 0.39 Total UPI outgoing data and non-data traffic: 3329 M 
Total UPI incoming data traffic:   92 M     UPI data traffic/Memory controller traffic: 0.28 Total UPI outgoing data and non-data traffic:  368 M 
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: 0.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic: 1077 M     UPI data traffic/Memory controller traffic: 0.40 Total UPI outgoing data and non-data traffic: 3170 M 
Total UPI incoming data traffic:   78 M     UPI data traffic/Memory controller traffic: 0.28 Total UPI outgoing data and non-data traffic:  306 M 
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
^C

[simonhf]

I also tried running two instances in parallel and they both failed at the same time:

$ sudo /usr/sbin/pcm 1 -nc -i=60 2>/dev/null | egrep --line-buffered "Total UPI " | perl -lane '$cc .= sprintf qq[%s ], $_; if(m~non-data~){ printf qq[%u %s\n], time(), $cc; undef $cc; }' & sudo /usr/sbin/pcm 1 -nc -i=60 2>/dev/null | egrep --line-buffered "Total UPI " | perl -lane '$cc .= sprintf qq[%s ], $_; if(m~non-data~){ printf qq[%u %s\n], time(), $cc; undef $cc; }' & 
1743481101 Total UPI incoming data traffic:  341 M     UPI data traffic/Memory controller traffic: 0.32 Total UPI outgoing data and non-data traffic: 1178 M 
1743481101 Total UPI incoming data traffic:  337 M     UPI data traffic/Memory controller traffic: 0.32 Total UPI outgoing data and non-data traffic: 1164 M 
1743481102 Total UPI incoming data traffic:  381 M     UPI data traffic/Memory controller traffic: 0.29 Total UPI outgoing data and non-data traffic: 1356 M 
1743481102 Total UPI incoming data traffic:  381 M     UPI data traffic/Memory controller traffic: 0.29 Total UPI outgoing data and non-data traffic: 1356 M 
1743481103 Total UPI incoming data traffic:  196 M     UPI data traffic/Memory controller traffic: 0.25 Total UPI outgoing data and non-data traffic:  705 M 
1743481103 Total UPI incoming data traffic:  195 M     UPI data traffic/Memory controller traffic: 0.25 Total UPI outgoing data and non-data traffic:  702 M 
1743481104 Total UPI incoming data traffic:  191 M     UPI data traffic/Memory controller traffic: 0.24 Total UPI outgoing data and non-data traffic:  687 M 
1743481104 Total UPI incoming data traffic:  191 M     UPI data traffic/Memory controller traffic: 0.24 Total UPI outgoing data and non-data traffic:  688 M 
1743481105 Total UPI incoming data traffic:  175 M     UPI data traffic/Memory controller traffic: 0.24 Total UPI outgoing data and non-data traffic:  626 M 
1743481105 Total UPI incoming data traffic:  175 M     UPI data traffic/Memory controller traffic: 0.24 Total UPI outgoing data and non-data traffic:  626 M 
1743481106 Total UPI incoming data traffic:  217 M     UPI data traffic/Memory controller traffic: 0.25 Total UPI outgoing data and non-data traffic:  794 M 
1743481106 Total UPI incoming data traffic:  217 M     UPI data traffic/Memory controller traffic: 0.25 Total UPI outgoing data and non-data traffic:  794 M 
1743481107 Total UPI incoming data traffic:  290 M     UPI data traffic/Memory controller traffic: 0.23 Total UPI outgoing data and non-data traffic: 1147 M 
1743481107 Total UPI incoming data traffic:  291 M     UPI data traffic/Memory controller traffic: 0.23 Total UPI outgoing data and non-data traffic: 1149 M 
1743481108 Total UPI incoming data traffic:  189 M     UPI data traffic/Memory controller traffic: 0.24 Total UPI outgoing data and non-data traffic:  718 M 
1743481108 Total UPI incoming data traffic:  189 M     UPI data traffic/Memory controller traffic: 0.24 Total UPI outgoing data and non-data traffic:  718 M 
1743481109 Total UPI incoming data traffic:  195 M     UPI data traffic/Memory controller traffic: 0.24 Total UPI outgoing data and non-data traffic:  704 M 
1743481109 Total UPI incoming data traffic:  194 M     UPI data traffic/Memory controller traffic: 0.24 Total UPI outgoing data and non-data traffic:  701 M 
1743481110 Total UPI incoming data traffic:  163 M     UPI data traffic/Memory controller traffic: 0.24 Total UPI outgoing data and non-data traffic:  588 M 
1743481110 Total UPI incoming data traffic:  164 M     UPI data traffic/Memory controller traffic: 0.24 Total UPI outgoing data and non-data traffic:  592 M 
1743481111 Total UPI incoming data traffic:  211 M     UPI data traffic/Memory controller traffic: 0.26 Total UPI outgoing data and non-data traffic:  754 M 
1743481111 Total UPI incoming data traffic:  210 M     UPI data traffic/Memory controller traffic: 0.26 Total UPI outgoing data and non-data traffic:  750 M 
1743481112 Total UPI incoming data traffic:  418 M     UPI data traffic/Memory controller traffic: 0.31 Total UPI outgoing data and non-data traffic: 1471 M 
1743481112 Total UPI incoming data traffic:  418 M     UPI data traffic/Memory controller traffic: 0.31 Total UPI outgoing data and non-data traffic: 1473 M 
1743481113 Total UPI incoming data traffic:  182 M     UPI data traffic/Memory controller traffic: 0.24 Total UPI outgoing data and non-data traffic:  650 M 
1743481113 Total UPI incoming data traffic:  182 M     UPI data traffic/Memory controller traffic: 0.24 Total UPI outgoing data and non-data traffic:  649 M 
1743481114 Total UPI incoming data traffic:  195 M     UPI data traffic/Memory controller traffic: 0.25 Total UPI outgoing data and non-data traffic:  695 M 
1743481114 Total UPI incoming data traffic:  194 M     UPI data traffic/Memory controller traffic: 0.25 Total UPI outgoing data and non-data traffic:  694 M 
1743481115 Total UPI incoming data traffic:  182 M     UPI data traffic/Memory controller traffic: 0.25 Total UPI outgoing data and non-data traffic:  652 M 
1743481115 Total UPI incoming data traffic:  183 M     UPI data traffic/Memory controller traffic: 0.25 Total UPI outgoing data and non-data traffic:  653 M 
1743481116 Total UPI incoming data traffic:  285 M     UPI data traffic/Memory controller traffic: 0.24 Total UPI outgoing data and non-data traffic: 1104 M 
1743481116 Total UPI incoming data traffic:  285 M     UPI data traffic/Memory controller traffic: 0.24 Total UPI outgoing data and non-data traffic: 1104 M 
1743481117 Total UPI incoming data traffic:  242 M     UPI data traffic/Memory controller traffic: 0.27 Total UPI outgoing data and non-data traffic:  875 M 
1743481117 Total UPI incoming data traffic:  242 M     UPI data traffic/Memory controller traffic: 0.27 Total UPI outgoing data and non-data traffic:  875 M 
1743481118 Total UPI incoming data traffic:  216 M     UPI data traffic/Memory controller traffic: 0.25 Total UPI outgoing data and non-data traffic:  814 M 
1743481118 Total UPI incoming data traffic:  217 M     UPI data traffic/Memory controller traffic: 0.25 Total UPI outgoing data and non-data traffic:  816 M 
1743481119 Total UPI incoming data traffic:  176 M     UPI data traffic/Memory controller traffic: 0.25 Total UPI outgoing data and non-data traffic:  630 M 
1743481119 Total UPI incoming data traffic:  175 M     UPI data traffic/Memory controller traffic: 0.25 Total UPI outgoing data and non-data traffic:  627 M 
1743481120 Total UPI incoming data traffic:  191 M     UPI data traffic/Memory controller traffic: 0.26 Total UPI outgoing data and non-data traffic:  693 M 
1743481120 Total UPI incoming data traffic:  191 M     UPI data traffic/Memory controller traffic: 0.26 Total UPI outgoing data and non-data traffic:  692 M 
1743481121 Total UPI incoming data traffic:  188 M     UPI data traffic/Memory controller traffic: 0.23 Total UPI outgoing data and non-data traffic:  694 M 
1743481121 Total UPI incoming data traffic:  188 M     UPI data traffic/Memory controller traffic: 0.23 Total UPI outgoing data and non-data traffic:  695 M 
1743481122 Total UPI incoming data traffic:  425 M     UPI data traffic/Memory controller traffic: 0.32 Total UPI outgoing data and non-data traffic: 1503 M 
1743481122 Total UPI incoming data traffic:  425 M     UPI data traffic/Memory controller traffic: 0.32 Total UPI outgoing data and non-data traffic: 1505 M 
1743481123 Total UPI incoming data traffic:  190 M     UPI data traffic/Memory controller traffic: 0.25 Total UPI outgoing data and non-data traffic:  683 M 
1743481123 Total UPI incoming data traffic:  189 M     UPI data traffic/Memory controller traffic: 0.25 Total UPI outgoing data and non-data traffic:  681 M 
1743481124 Total UPI incoming data traffic:  196 M     UPI data traffic/Memory controller traffic: 0.23 Total UPI outgoing data and non-data traffic:  714 M 
1743481124 Total UPI incoming data traffic:  196 M     UPI data traffic/Memory controller traffic: 0.23 Total UPI outgoing data and non-data traffic:  714 M 
1743481125 Total UPI incoming data traffic:  691 M     UPI data traffic/Memory controller traffic: 0.32 Total UPI outgoing data and non-data traffic: 2382 M 
1743481125 Total UPI incoming data traffic:  692 M     UPI data traffic/Memory controller traffic: 0.32 Total UPI outgoing data and non-data traffic: 2388 M 
1743481126 Total UPI incoming data traffic:  449 M     UPI data traffic/Memory controller traffic: 0.31 Total UPI outgoing data and non-data traffic: 1574 M 
1743481126 Total UPI incoming data traffic:  448 M     UPI data traffic/Memory controller traffic: 0.31 Total UPI outgoing data and non-data traffic: 1571 M 
1743481127 Total UPI incoming data traffic:  282 M     UPI data traffic/Memory controller traffic: 0.24 Total UPI outgoing data and non-data traffic: 1080 M 
1743481127 Total UPI incoming data traffic:  281 M     UPI data traffic/Memory controller traffic: 0.24 Total UPI outgoing data and non-data traffic: 1078 M 
1743481128 Total UPI incoming data traffic:  246 M     UPI data traffic/Memory controller traffic: 0.26 Total UPI outgoing data and non-data traffic:  913 M 
1743481128 Total UPI incoming data traffic:  246 M     UPI data traffic/Memory controller traffic: 0.26 Total UPI outgoing data and non-data traffic:  913 M 
1743481129 Total UPI incoming data traffic:  204 M     UPI data traffic/Memory controller traffic: 0.26 Total UPI outgoing data and non-data traffic:  732 M 
1743481129 Total UPI incoming data traffic:  204 M     UPI data traffic/Memory controller traffic: 0.26 Total UPI outgoing data and non-data traffic:  732 M 
1743481130 Total UPI incoming data traffic:  176 M     UPI data traffic/Memory controller traffic: 0.25 Total UPI outgoing data and non-data traffic:  630 M 
1743481130 Total UPI incoming data traffic:  176 M     UPI data traffic/Memory controller traffic: 0.25 Total UPI outgoing data and non-data traffic:  629 M 
1743481131 Total UPI incoming data traffic:  190 M     UPI data traffic/Memory controller traffic: 0.25 Total UPI outgoing data and non-data traffic:  682 M 
1743481131 Total UPI incoming data traffic:  191 M     UPI data traffic/Memory controller traffic: 0.25 Total UPI outgoing data and non-data traffic:  684 M 
1743481132 Total UPI incoming data traffic:  403 M     UPI data traffic/Memory controller traffic: 0.30 Total UPI outgoing data and non-data traffic: 1418 M 
1743481132 Total UPI incoming data traffic:  403 M     UPI data traffic/Memory controller traffic: 0.30 Total UPI outgoing data and non-data traffic: 1420 M 
1743481133 Total UPI incoming data traffic:  228 M     UPI data traffic/Memory controller traffic: 0.26 Total UPI outgoing data and non-data traffic:  809 M 
1743481133 Total UPI incoming data traffic:  227 M     UPI data traffic/Memory controller traffic: 0.26 Total UPI outgoing data and non-data traffic:  806 M 
1743481134 Total UPI incoming data traffic:  197 M     UPI data traffic/Memory controller traffic: 0.25 Total UPI outgoing data and non-data traffic:  704 M 
1743481134 Total UPI incoming data traffic:  197 M     UPI data traffic/Memory controller traffic: 0.25 Total UPI outgoing data and non-data traffic:  705 M 
1743481135 Total UPI incoming data traffic:  203 M     UPI data traffic/Memory controller traffic: 0.24 Total UPI outgoing data and non-data traffic:  743 M 
1743481135 Total UPI incoming data traffic:  202 M     UPI data traffic/Memory controller traffic: 0.24 Total UPI outgoing data and non-data traffic:  743 M 
1743481136 Total UPI incoming data traffic:  304 M     UPI data traffic/Memory controller traffic: 0.24 Total UPI outgoing data and non-data traffic: 1175 M 
1743481136 Total UPI incoming data traffic:  304 M     UPI data traffic/Memory controller traffic: 0.24 Total UPI outgoing data and non-data traffic: 1176 M 
1743481137 Total UPI incoming data traffic:  249 M     UPI data traffic/Memory controller traffic: 0.26 Total UPI outgoing data and non-data traffic:  903 M 
1743481137 Total UPI incoming data traffic:  249 M     UPI data traffic/Memory controller traffic: 0.26 Total UPI outgoing data and non-data traffic:  903 M 
1743481138 Total UPI incoming data traffic:  224 M     UPI data traffic/Memory controller traffic: 0.26 Total UPI outgoing data and non-data traffic:  800 M 
1743481138 Total UPI incoming data traffic:  224 M     UPI data traffic/Memory controller traffic: 0.26 Total UPI outgoing data and non-data traffic:  801 M 
1743481139 Total UPI incoming data traffic:  247 M     UPI data traffic/Memory controller traffic: 0.27 Total UPI outgoing data and non-data traffic:  887 M 
1743481139 Total UPI incoming data traffic:  247 M     UPI data traffic/Memory controller traffic: 0.27 Total UPI outgoing data and non-data traffic:  886 M 
1743481140 Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: 0.00 Total UPI outgoing data and non-data traffic:    0   
1743481140 Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: 0.00 Total UPI outgoing data and non-data traffic:    0   
1743481141 Total UPI incoming data traffic: 2235 M     UPI data traffic/Memory controller traffic: 0.38 Total UPI outgoing data and non-data traffic: 6265 M 
1743481141 Total UPI incoming data traffic: 2158 M     UPI data traffic/Memory controller traffic: 0.38 Total UPI outgoing data and non-data traffic: 6059 M 
1743481142 Total UPI incoming data traffic:  357 M     UPI data traffic/Memory controller traffic: 0.40 Total UPI outgoing data and non-data traffic: 1166 M 
1743481142 Total UPI incoming data traffic:  351 M     UPI data traffic/Memory controller traffic: 0.40 Total UPI outgoing data and non-data traffic: 1146 M 
1743481143 Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
1743481143 Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
1743481144 Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
1743481144 Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
1743481145 Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
1743481145 Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
1743481146 Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
1743481146 Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   

[simonhf]

I tried restarting pcm whenever the controller traffic is 0.00 or -1.00, and noticed that this happens on the first second of every minute:

$ perl -e 'pcm(); while(1){ $_ = <$fh>; chomp; $cc .= sprintf qq[%s ], $_; if(m~non-data~){ printf qq[%u %s %s\n], time(), scalar localtime, $cc; if($cc =~ m~controller traffic: (0.00|-1.00)~){ pcm(); } undef $cc; } }sub pcm{ close $fh; open($fh, q[sudo /usr/sbin/pcm 1 -nc 2>/dev/null | egrep --line-buffered "Total UPI "|]); }'
1743482800 Mon Mar 31 21:46:40 2025 Total UPI incoming data traffic:  195 M     UPI data traffic/Memory controller traffic: 0.31 Total UPI outgoing data and non-data traffic:  661 M 
...
1743482819 Mon Mar 31 21:46:59 2025 Total UPI incoming data traffic:  174 M     UPI data traffic/Memory controller traffic: 0.24 Total UPI outgoing data and non-data traffic:  651 M 
1743482820 Mon Mar 31 21:47:00 2025 Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: 0.00 Total UPI outgoing data and non-data traffic:    0   
1743482824 Mon Mar 31 21:47:04 2025 Total UPI incoming data traffic:  218 M     UPI data traffic/Memory controller traffic: 0.32 Total UPI outgoing data and non-data traffic:  740 M 
...
1743482879 Mon Mar 31 21:47:59 2025 Total UPI incoming data traffic:  203 M     UPI data traffic/Memory controller traffic: 0.26 Total UPI outgoing data and non-data traffic:  736 M 
1743482880 Mon Mar 31 21:48:00 2025 Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: 0.00 Total UPI outgoing data and non-data traffic:    0   
1743482884 Mon Mar 31 21:48:04 2025 Total UPI incoming data traffic:  168 M     UPI data traffic/Memory controller traffic: 0.23 Total UPI outgoing data and non-data traffic:  611 M 
...
^C

[simonhf]

Here's another example where all minute seconds are 0 except for the 1st one which is on the 3rd second:

$ perl -e 'pcm(); while(1){ $_ = <$fh>; chomp; $cc .= sprintf qq[%s ], $_; if(m~non-data~){ printf qq[%u %s %s\n], time(), scalar localtime, $cc; if($cc =~ m~controller traffic: (0.00|-1.00)~){ pcm(); } undef $cc; } }sub pcm{ close $fh; open($fh, q[sudo ~/pcm/build/bin/pcm 1 -nc 2>/dev/null | egrep --line-buffered "Total UPI "|]); }' | egrep "data traffic:    0"
1743484023 Mon Mar 31 22:07:03 2025 Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: -1.00 Total UPI outgoing data and non-data traffic:    0   
1743484080 Mon Mar 31 22:08:00 2025 Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: 0.00 Total UPI outgoing data and non-data traffic:    0   
1743484140 Mon Mar 31 22:09:00 2025 Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: 0.00 Total UPI outgoing data and non-data traffic:    0   
1743484200 Mon Mar 31 22:10:00 2025 Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: 0.00 Total UPI outgoing data and non-data traffic:    0   
1743484260 Mon Mar 31 22:11:00 2025 Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: 0.00 Total UPI outgoing data and non-data traffic:    0   
1743484320 Mon Mar 31 22:12:00 2025 Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: 0.00 Total UPI outgoing data and non-data traffic:    0   
1743484380 Mon Mar 31 22:13:00 2025 Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: 0.00 Total UPI outgoing data and non-data traffic:    0   
1743484440 Mon Mar 31 22:14:00 2025 Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: 0.00 Total UPI outgoing data and non-data traffic:    0   
1743484500 Mon Mar 31 22:15:00 2025 Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: 0.00 Total UPI outgoing data and non-data traffic:    0   
1743484560 Mon Mar 31 22:16:00 2025 Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: 0.00 Total UPI outgoing data and non-data traffic:    0   
1743484620 Mon Mar 31 22:17:00 2025 Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: 0.00 Total UPI outgoing data and non-data traffic:    0   
^C

And yet another example where restarting it causes always minute second 1 to be the problem second:

$ perl -e 'pcm(); while(1){ $_ = <$fh>; chomp; $cc .= sprintf qq[%s ], $_; if(m~non-data~){ printf qq[%u %s %s\n], time(), scalar localtime, $cc; if($cc =~ m~controller traffic: (0.00|-1.00)~){ pcm(); } undef $cc; } }sub pcm{ close $fh; open($fh, q[sudo ~/pcm/build/bin/pcm 1 -nc 2>/dev/null | egrep --line-buffered "Total UPI "|]); }' | egrep "data traffic:    0"
1743484681 Mon Mar 31 22:18:01 2025 Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: 0.00 Total UPI outgoing data and non-data traffic:    0   
1743484741 Mon Mar 31 22:19:01 2025 Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: 0.00 Total UPI outgoing data and non-data traffic:    0   
1743484801 Mon Mar 31 22:20:01 2025 Total UPI incoming data traffic:    0       UPI data traffic/Memory controller traffic: 0.00 Total UPI outgoing data and non-data traffic:    0   
^C

[simonhf]

After more investigation, I think the problem is that only one instance of pcm can be started at a time? I think I have another instance starting automatically in the background and only running for 1 second every minute, and this conflicts with the other instance running.

[rdementi]

yes, you are correct. We do not support running multiple instances of pcm at the same time.