nvme interrupt counters got reset after suspend/resume

[David Wang]

Hi,

I noticed that on my system, the counters from /proc/interrupts
for nvme got reset after I suspend and then resume the system.
For example, before `systemctl suspend`:
$ cat /proc/interrupts 
            CPU0       CPU1       CPU2       CPU3       CPU4       CPU5       CPU6       CPU7
...
  38:          0          0          0         22          0          0          0          0 IR-PCI-MSIX-0000:25:00.0    0-edge      nvme0q0
  39:          0          0          0          0          0          0          0          0 IR-PCI-MSIX-0000:22:00.0    0-edge      enp34s0
  40:         78          0          0          0          0          0          0          0 IR-PCI-MSIX-0000:25:00.0    1-edge      nvme0q1
  41:          0        147          0          0          0          0          0          0 IR-PCI-MSIX-0000:25:00.0    2-edge      nvme0q2
  42:          0          0         13          0          0          0          0          0 IR-PCI-MSIX-0000:25:00.0    3-edge      nvme0q3
  43:          0          0          0          9          0          0          0          0 IR-PCI-MSIX-0000:25:00.0    4-edge      nvme0q4
  44:          0          0          0          0         87          0          0          0 IR-PCI-MSIX-0000:25:00.0    5-edge      nvme0q5
  45:          0          0          0          0          0        112          0          0 IR-PCI-MSIX-0000:25:00.0    6-edge      nvme0q6
  46:          0          0          0          0          0          0         12          0 IR-PCI-MSIX-0000:25:00.0    7-edge      nvme0q7
  47:          0          0          0          0          0          0          0          8 IR-PCI-MSIX-0000:25:00.0    8-edge      nvme0q8

And right after resume the system, values are reset to 0s:
$ cat /proc/interrupts 
            CPU0       CPU1       CPU2       CPU3       CPU4       CPU5       CPU6       CPU7
...
  38:          0          0          0         21          0          0          0          0 IR-PCI-MSIX-0000:25:00.0    0-edge      nvme0q0
  39:          0          0          0          0          0          0          0          0 IR-PCI-MSIX-0000:22:00.0    0-edge      enp34s0
  40:          0          0          0          0          0          0          0          0 IR-PCI-MSIX-0000:25:00.0    1-edge      nvme0q1
  41:          0          0          0          0          0          0          0          0 IR-PCI-MSIX-0000:25:00.0    2-edge      nvme0q2
  42:          0          0          0          0          0          0          0          0 IR-PCI-MSIX-0000:25:00.0    3-edge      nvme0q3
  43:          0          0          0          0          0          0          0          0 IR-PCI-MSIX-0000:25:00.0    4-edge      nvme0q4
  44:          0          0          0          0          0          0          0          0 IR-PCI-MSIX-0000:25:00.0    5-edge      nvme0q5
  45:          0          0          0          0          0          0          0          0 IR-PCI-MSIX-0000:25:00.0    6-edge      nvme0q6
  46:          0          0          0          0          0          0          0          0 IR-PCI-MSIX-0000:25:00.0    7-edge      nvme0q7
  47:          0          0          0          0          0          0          0          0 IR-PCI-MSIX-0000:25:00.0    8-edge      nvme0q8

This does not happend to counters for other interrupts on my system.
Not sure whether this is designed explicitly this way, or happended to be this way to make suspend/resume work,
or there is some bug behind this.
Just bring this up for discussion since I failed to find any discussion about it.

Thanks
David.