sg_get_mem_stats(3)sg_get_mem_stats(3)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 ac‐
cess the swap statistics. Making the program setgid kmem should be suf‐
ficient. 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 ALSOstatgrab(3)WEBSITE
⟨http://www.i-scream.org/libstatgrab/⟩
i-scream 2013-06-17 sg_get_mem_stats(3)
