07-25-2013
Short answer is, "cached" counts as some more "free". unused = free + cache.
So don't panic when you see "0% free"! There have been Linux admins who have rebooted their servers daily to 'clean the cache' until they realized that cache counts as free.
The reason cache is counted separately is because cache is important. You want there to be plenty of cache. If you have so many things running that you have no room for cache, that's bad.
Last edited by Corona688; 07-25-2013 at 07:46 PM..
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LEARN ABOUT DEBIAN
sg_get_swap_stats
sg_get_mem_stats(3) Library Functions Manual sg_get_mem_stats(3)
NAME
sg_get_mem_stats, sg_get_swap_stats - get VM statistics
SYNOPSIS
#include <statgrab.h>
sg_mem_stats *sg_get_mem_stats(void);
sg_swap_stats *sg_get_swap_stats(void);
DESCRIPTION
Memory statistics are accessed through the sg_get_mem_stats function. It returns a pointer to a static sg_mem_stats.
The sg_get_swap_stats returns returns swap statistics. It returns a pointer to a static sg_swap_stats.
On the FreeBSD operating system elevated privileges are required to access the swap statistics. Making the program setgid kmem should be
sufficient. Programs running as root will not have this problem.
RETURN VALUES
The VM system calls can return a pointer to either a sg_mem_stats or a sg_swap_stats.
typedef struct{
long long total;
long long free;
long long used;
long long cache;
}sg_mem_stats;
total The total amount of memory in bytes.
free The total free memory in bytes.
used The total used memory in bytes.
cache The amount of cache used in bytes.
typedef struct{
long long total;
long long used;
long long free;
}sg_swap_stats;
total The total swap space in bytes.
used The used swap in bytes.
free The free swap in bytes.
TODO
Add a function to hold open the file descriptor to the kernel memory structures. Doing this would allow the elevated privileges to be
dropped early on.
SEE ALSO
statgrab(3)
WEBSITE
http://www.i-scream.org/libstatgrab/
i-scream $Date: 2005/04/25 11:25:45 $ sg_get_mem_stats(3)