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Linux page cache

Jan 10 at 12:29 PM


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Hi All,

I've a question regarding the linux page cache for SAP systems. This is with reference to the sap note 1382721.

The note says to not use the free command to determine the available free memory in the server but rather use the /proc/meminfo output, which is calculated as cached - shmem. The note further explains that the sap extended memory uses the cache region and hence can't be freed. Ideally, the extended memory should be using the shared memory region. under what circumstances would the objects in the extended memory be cached? Appreciate your thoughts and your time.



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1 Answer

Adam Gaspar
Jan 10 at 01:46 PM

Hello Jerry,

the "cached" value reported by the "free" command or in meminfo includes many areas, such as: pagecache, and the shared memory (from SAP and DB). The SAP extended memory is part of the shared memory, but it is counted towards cached as well (this is what the note explain)

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