A large number of page ins may be a symptom of a large number of recent page outs.
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To find out what process is reading these pages in, check the resident size of the processes you are running, and see which ones are increasing in size.

A large number of page ins may also occur when a large process has just stopped, and the kernel decides to fill that space with memory pages owned by other processes. Make sure that an important process hasn’t died unexpectedly.

Tags: unix_alarms