NAME

       sg_get_mem_stats,    sg_get_mem_stats_r,   sg_free_mem_stats,   sg_get_swap_stats,   sg_get_swap_stats_r,
       sg_free_swap_stats - get VM statistics

SYNOPSIS

       #include <statgrab.h>

       sg_mem_stats *sg_get_mem_stats (size_t *entries);

       sg_mem_stats *sg_get_mem_stats_r (size_t *entries);

       sg_error sg_free_mem_stats (sg_mem_stats *data);

       sg_swap_stats *sg_get_swap_stats (size_t *entries);

       sg_swap_stats *sg_get_swap_stats_r (size_t *entries);

       sg_error sg_free_swap_stats (sg_swap_stats *data);

DESCRIPTION

       Memory statistics are accessed through  the  sg_get_mem_stats()  function  and  the  sg_get_mem_stats_r()
       function.  Both  return a pointer to a sg_mem_stats buffer.  Note that this statistic doesn't need to map
       the entire physical memory usage, it represents the real memory usable by the operating system.

       Memory statistics are accessed through the sg_get_swap_stats()  function  and  the  sg_get_swap_stats_r()
       function. Both return a pointer to a sg_swap_stats buffer.

       API Shortcut

       ┌────────────────────┬─────────────────┬────────────────────────────┐
       │function            │ returns         │ data owner                 │
       ├────────────────────┼─────────────────┼────────────────────────────┤
       │sg_get_mem_stats    │ sg_mem_stats *  │ libstatgrab (thread local) │
       ├────────────────────┼─────────────────┼────────────────────────────┤
       │sg_get_mem_stats_r  │ sg_mem_stats *  │ caller                     │
       ├────────────────────┼─────────────────┼────────────────────────────┤
       │sg_get_swap_stats   │ sg_swap_stats * │ libstatgrab (thread local) │
       ├────────────────────┼─────────────────┼────────────────────────────┤
       │sg_get_swap_stats_r │ sg_swap_stats * │ caller                     │
       └────────────────────┴─────────────────┴────────────────────────────┘
       The  sg_mem_stats  buffer  received  from sg_get_mem_stats_r() and the sg_swap_stats buffer received from
       sg_get_swap_stats_r() must be freed using sg_free_mem_stats() or the sg_free_swap_stats(),  respectively,
       when not needed any more. The caller is responsible for doing it.

       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{
               unsigned long long total;
               unsigned long long free;
               unsigned long long used;
               unsigned long long cache;
               time_t systime;
       } sg_mem_stats;

       total  The total amount of real memory in bytes.

       free   The free amount of real memory in bytes.

       used   The used amount of real memory in bytes.

       cache  The amount of real memory in bytes used for caching.

       systime
              the timestamp when the above stats where collected in seconds since epoch

       typedef struct {
               unsigned long long total;
               unsigned long long used;
               unsigned long long free;
               time_t systime;
       } sg_swap_stats;

       total  The total swap space in bytes.

       used   The used swap in bytes.

       free   The free swap in bytes.

       systime
              The timestamp when the above stats where collected in seconds since epoch

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/⟩