[NTLUG:Discuss] True memory usage

[David I S Mandala]

Hmm, is that true? I would have thought the better number would be

cached + free = total memory potentially avalible.

I understood that the cached memory is the disk cache and that Linux 
uses most all free memory to speed up the disk, but that when necessary 
it will relinquish it back for application use before the swap memory is 
used.

Cheers,

David

Chris Cox wrote:
> Robert Thompson wrote:
>>Hello,
>>
>>	I am trying to figure out the best way to get the 'true' memory usage
>>for a machine. When I do a free I think I'm supposed to look at the
>>'used' section under the -/+ buffers/cache line:
>>
>>$ free
>>             total       used       free     shared    buffers
>>cached
>>Mem:        904832     895972       8860          0      18060
>>565936
>>-/+ buffers/cache:     311976     592856
>>Swap:       755044        164     754880
>>
>>	So the above means I am using 311M of memory?
>>
>>	When I attempt to add up the memory from doing a ps aux and adding the
>>RSS (resident set size) I get something different (larger than total
>>memory):
> 
> It can be complicated.  Do you need a VERY exact number?  I would think
> the value in free would work fine (or /proc/meminfo).  ps can be
> misleading since threaded applications will show up multiple times with
> the same RSS (or even SZ) size.  There can be other things shared as
> well.
> 
> 
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David Mandala <davidm at them dot com>
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