Messages in this thread |  | | Date | Wed, 6 Nov 2013 00:39:06 +0200 | From | "Kirill A. Shutemov" <> | Subject | Re: [RFC PATCH -mm] provide estimated available memory in /proc/meminfo |
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On Tue, Nov 05, 2013 at 05:38:52PM -0500, Rik van Riel wrote: > Many load balancing and workload placing programs check /proc/meminfo > to estimate how much free memory is available. They generally do this > by adding up "free" and "cached", which was fine ten years ago, but > is pretty much guaranteed to be wrong today. > > It is wrong because Cached includes memory that is not freeable as > page cache, for example shared memory segments, tmpfs, and ramfs, > and it does not include reclaimable slab memory, which can take up > a large fraction of system memory on mostly idle systems with lots > of files. > > Currently, the amount of memory that is available for a new workload, > without pushing the system into swap, can be estimated from MemFree, > Active(file), Inactive(file), and SReclaimable, as well as the "low" > watermarks from /proc/zoneinfo.
ramfs pages first go to (in)active lists, moves to unevictable later, so it's not really true already. ;)
-- Kirill A. Shutemov
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