sg_get_mem_stats man page

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_errorsg_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_errorsg_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

functionreturnsdata owner
sg_get_mem_statssg_mem_stats *libstatgrab (thread local)
sg_get_mem_stats_rsg_mem_stats *caller
sg_get_swap_statssg_swap_stats *libstatgrab (thread local)
sg_get_swap_stats_rsg_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/

Referenced By

sg_intro(3), statgrab(3).

sg_free_mem_stats(3), sg_free_swap_stats(3), sg_get_mem_stats_r(3), sg_get_swap_stats(3) and sg_get_swap_stats_r(3) are aliases of sg_get_mem_stats(3).

2013-06-17 i-scream