Why pmwatch result is different from pcm-memory.x?

[sheperdh]

From my test, I found pmwatch result is different from pcm-memory.x.
From pcm-memory.x, I saw there is no pmm activity, but from pmwatch result, I see activity on each dimm.
Any reason for that?

[htg1]

Was pmm idle when you ran the test?
Please clarify if you are asking pmwatch is reporting incorrect activity when pmm is idle or why pcm-memory.x is not reporting any activity?

[GrayXu]

Was pmm idle when you ran the test? Please clarify if you are asking pmwatch is reporting incorrect activity when pmm is idle or why pcm-memory.x is not reporting any activity?

I guess what he means is that pcm-memory will reports the throughput of the memory channel. However, when PM is idle and pcm-memory reports zero, pmwatch will report some operations from the CPU.

On my platform, pmwatch 1 returns cpu_read_ops=54 and cpu_write_ops=17.