when I run the atop -r /var/log/atop/...
I see from the atop screen this
PAG | scan 641376 | steal 635209 | stall
the PAG is colored with red
can someone explain what PAG explain from the atop , and what this problem means ?
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PAG Paging frequency. This line contains the number of scanned pages ('scan') due to the fact that free memory drops below a particular threshold and the number times that the kernel tries to reclaim pages due to an urgent need (`stall').
Also the number of memory pages the system read from swap space ('swin') > and the number of memory pages the system wrote to swap space ('swout') > are shown.
Basically, it (normally) indicates that your system is low on memory, which is not a good thing, hence it is in red.
sar(1)Number of pages the system has reclaimed from cache (pagecache and swapcache) per second to satisfy its memory demands.