[lug] "Cache" under linux

D. Stimits stimits at attbi.com
Wed Mar 12 12:52:29 MST 2003

Eric Peers wrote:

> When I run top, I notice that I have very little free
> memory in my system, and yet the process memory usage
> count does not reflect this used memory.
> So I found a command called free:
> crampon> free
>              total       used       free     shared
> buffers     cached
> Mem:        998748     899816      98932          0
>  134052     558556
> what is this "cached" memory usage? Is it for virtual
> memory? is there a way to control the amount of it
> which is used for paging? Should I even worry about
> it? (because it seems to grow in size the longer I use
> my system).
>    --eric

Cached memory is not a bad thing, and is not the same as something that 
has claimed that  memory for itself. There is no benefit to controlling 
it. Look at it this way...your computer has a short term memory that it 
can use to remember at high speed (in ram) what it took great effort to 
find before (file system access)...now it is just telling you that it 
still remembers what it found, and will have it ready quickly if 
anything wants it again. On the other hand, if it needs the ram for 
anything at all, it will toss the older cache out the window without 
hesitating. It can mean an extreme boost in system responsiveness.

D. Stimits, stimits AT attbi DOT com

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