The names are quite different under SuSE, but I think I can have a go at
clarification.
Quoting Simon Hobson <shobson-lists@colony.com>:
> Can someone clarify the meaning of the various memory usage stats in Linux ?
>
> In both top and the graphs provided by Slox, there are categories of
> free, buffered, shared, cached - I'm not clear what is buffered.
>
> OK, as I understand it :
>
> free is simply not being used...
That's the obvious part...
> ...and normally there shouldn't be much
> of it as cached should increase to use most of the spare memory
> available.
I tend get about 200/512 MB occupied before I start any particular process that
benefits from caching.
> shared is memory that is used to hold stuff that is shared between
> different processes - particularly the in-memory copy of a binary
> that is being run multiple times.
I am not entirely sure. It must have something to do with more than one process
and maybe some interaction between processes.
> cached is used to hold in-memory copies of stuff that is on disk - so
> improving performance when/if it is accessed again.
Yes, and if you have high memory capacity it will (or should) rarely be used.
> But what is buffered ?
I think it's the equivalent of memory stack. If you malloc() some resources,
then it will only 'virtually' be used.
> Also, according to the graphs made with rrd, we are running at about
> 160M free, 150M buffered, 780M shared, and 930M cached - 2G total.
> top reports about 110M free, 0 shared (I assume that is what shrd
> means), and 150M buffered. The differences in the numbers can be
> explained by timing (they were taken at different times), but the
> difference between 780M and 0M shared - is that just a different way
> of reporting the usage ?
It sounds like one tool does not have the notion of _shared_ memory. In the KDE
system monitor I can't see such a thing either.
--
Roy Schestowitz
http://schestowitz.com/
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