* kernel mem_map reservation with hugepages
@ 2014-06-12 21:47 Alkalay, Amitai
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From: Alkalay, Amitai @ 2014-06-12 21:47 UTC (permalink / raw)
To: linux-mm
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Hi,
According to this page<http://linux-mm.org/WhereDidMyMemoryGo> about 1.36% of the system memory is reserved to mem_map (I confirmed it before in the code - I saw that the kernel indeed saves a struct of 65 bytes for each page, meaning 63 structs per page).
I have a server (CentOS6) with 256GB of RAM, so it means that the kernel reserves about 4GB for mem_map.
Most of the pages in my server are hugepages, using the kernel command line argument "hugepages=X".
I believe this means that the kernel can reserve a much smaller amount of memory for the mappings - since there are much less pages (i.e. if all pages are huges it can reserve 8MB instead of 4GB).
Am I right?
Any suggestions if and how it can be done?
Thanks,
Amitai
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2014-06-12 21:47 kernel mem_map reservation with hugepages Alkalay, Amitai
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