Entry in /proc/meminfo

Question

I am now study linux. cat /proc/meminfo produces as following. Please tell me the mean of entry \"Active(file)/Inactive(file)\". I can\'t find the explanation of these entry

Answer 1

According to the output, result of Active(file) + Inactive(file) + Shmem doesn't equal to that of Cached + Buffer + SwapCached

Answer 2

And FYI.

1. Active = Active(anon) + Active(file) Inactive = Inactive(anon) + Inactive(file)
2. Active(file), Inactive(file) has file back-end which means its original file is in disk but to use it faster it was loaded on RAM.
3. Active(file) + Inactive(file) + Shmem = Cached + Buffer + SwapCached

Answer 3

Active — The total amount of buffer or page cache memory, in kilobytes, that is in active use. This is memory that has been recently used and is usually not reclaimed for other purposes.

Inactive — The total amount of buffer or page cache memory, in kilobytes, that are free and and available. This is memory that has not been recently used and can be reclaimed for other purposes.

Ref : https://www.centos.org/docs/5/html/5.1/Deployment_Guide/s2-proc-meminfo.html