Interpreting /proc/meminfo. How much free memory do I have?

antonio.dibacco antonio.dibacco at
Mon Mar 27 20:38:22 EST 2006

I don't understand the meaning of "Inactive". They are not used but the 
kernel cannot give this memory to a requesting process because we tipically 
don't have a swap device on a linux embedded board. Where we can store the 
Inactive page? Am I wrong?
If I run a process that continuosly allocates memory and print out the total 
allocated memory when it receives SIGINT or SIGTERM, I think I get the real 
"free memory"! 


Eberhard Stoll Scrive: 

> Roger Larsson schrieb: 
>>On måndag 27 mars 2006 08.49, antonio.dibacco wrote:
>>>I'm a little bit puzzled with the fields in /proc/meminfo. Which fields
>>>have I to sum up to get the amount of free memory?
>>>From a 2.6 /proc/meminfo
>>MemTotal:       515532 kB
>>MemFree:          6012 kB
>>Buffers:         79964 kB
>>Cached:          83264 kB
>>SwapCached:      82840 kB
>>Active:         294024 kB
>>Inactive:       130304 kB
>>- - - 
>>Completely free is only MemFree. But those pages are only needed for
>>interrupt handlers (close enough). 
>>Cached pages are also free but since they contain data that maybe will
>>be needed again (unmodified data that already is on disk) they are not
>>returned to MemFree state. 
>>Inactive pages has not been in use for awhile and can be written out
>>if needed (some are probably unmodified and quick to get)
> Active + Inactive + MemFree is not equal MemTotal. Where can i find the
> offset? 
> Thanks,
> Eberhard 
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