How is free calculation of used memory?

Question

How to calculate used memory for free and why is it different from what / proc reports?

# cat /proc/*/status | grep VmSize | awk '{sum += $2} END {print sum}'
281260

But it says for free:

# free
             total       used       free     shared    buffers     cached
Mem:        524288     326488     197800          0          0          0

Who is right? Are you using 281260kb or 326488kb memory?

Answer 1

The name asks: "How to calculate the used memory for free?"

Answer: he requests the OS, which must track this in order to do this work.

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Answer 2

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