cached - any tools to explain what has been cached on linux

[Lennart Sorensen]

On Sun, Oct 14, 2007 at 05:33:05PM -0400, tleslie wrote:
> I set up a machine with postgres,
> and a 16GB of RAM and its really quick as compared to
> a similar machine running postgres with similar DB
> and only 3GB RAM.
> 
> Does anyone know of any utils or profiling tools
> that would explain what the cache in linux
> is doing?
> 
> TOP: 
> 
> Mem:  16440144k total, 12889668k used,  3550476k free,    69076k buffers
> Swap:  2104472k total,    10732k used,  2093740k free, 10203404k cached
> 
> i'd love to know how/what is in that 10 GB of cache
> 
> i know it stores allocation blocks for programs to use, but its
> got to be so much more then that.

Disk cache. :)  So even if postgres only uses a bit of ram itself, the
whole database might end up read into ram, so only writes have to go to
disk.  That would be rather fast.

--
Len Sorensen
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