Re: [Hampshire] Linux RAM usages

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Author: Hugo Mills
Date:  
To: Hampshire LUG Discussion List
Subject: Re: [Hampshire] Linux RAM usages

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On Tue, Jul 13, 2010 at 05:59:46PM +0100, James Courtier-Dutton wrote:
> I notice that Linux tends to always use about 95% of RAM all the time,
> for cache mostly.
> Is there any sysctl that could move this to 80% ?


Not that I'm aware of. Linux uses all the spare RAM for cache,
because having spare RAM unused would be a waste. If a process
actually needs more RAM (because it's starting up and allocating
memory, say), then some files are evicted from cache to make space.

There's a "swappiness" control that governs how much working set
(i.e. the memory actually used by applications and not otherwise on
disk) is swapped out to the pagefile, and how aggressively, but that
won't help you with the filesystem cache bits.

> Please don't ask me why because the answer it stupid!!!


Why? :)

(If the answer is, "someone thinks that the machine is short of RAM
and they need more", then some education is in order).

Hugo.

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