[QUESTION 2/2] Simple question about pagemap

From: Akira Nakajima
Date: Mon Jun 29 2015 - 08:10:29 EST


Sorry for simple question.

2. What is useful use of pagemap for troubleshooting?

I like to know PFN mapping, but my boss says
"On RHEL6 and RHEL7, what can we use for?"

For example, we can use the USS(Unique Set Size) to invest process memory leak.

Calculating USS
/proc/PID/pagemap has physical address and kpagecount is 1.
USS = Total of above condition pages x 4KB.

So, we can do the same using smaps.
cat /proc/PID/smaps | awk '/^Private/{sum += $2}END{print sum}'


What is useful use of pagemap for troubleshooting? (It's difficult by smaps)
(soft-dirty is above kernel 3.11. RHEL7 is not supported.)
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