sysinfo() - Unix, Linux System Call

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Copyright © 2014 by tutorialspoint

int sysinfo(struct sysinfo *info); 


struct sysinfo {
        long uptime;             /* Seconds since boot */
        unsigned long loads[3];  /* 1, 5, and 15 minute load averages */
        unsigned long totalram;  /* Total usable main memory size */
        unsigned long freeram;   /* Available memory size */
        unsigned long sharedram; /* Amount of shared memory */
        unsigned long bufferram; /* Memory used by buffers */
        unsigned long totalswap; /* Total swap space size */
        unsigned long freeswap;  /* swap space still available */
        unsigned short procs;    /* Number of current processes */
        char _f[22];             /* Pads structure to 64 bytes */
};


and the sizes were given in bytes. Since Linux 2.3.23 (i386), 2.3.48
(all architectures) the structure is



struct sysinfo {
        long uptime;             /* Seconds since boot */
        unsigned long loads[3];  /* 1, 5, and 15 minute load averages */
        unsigned long totalram;  /* Total usable main memory size */
        unsigned long freeram;   /* Available memory size */
        unsigned long sharedram; /* Amount of shared memory */
        unsigned long bufferram; /* Memory used by buffers */
        unsigned long totalswap; /* Total swap space size */
        unsigned long freeswap;  /* swap space still available */
        unsigned short procs;    /* Number of current processes */
        unsigned long totalhigh; /* Total high memory size */
        unsigned long freehigh;  /* Available high memory size */
        unsigned int mem_unit;   /* Memory unit size in bytes */
        char _f[20-2*sizeof(long)-sizeof(int)]; /* Padding for libc5 */
};


and the sizes are given as multiples of mem_unit bytes.


sysinfo() provides a simple way of getting overall system statistics.  This is more
portable than reading /dev/kmem.
For an example of its use, see
intro(2).


The Linux kernel has a
sysinfo() system call since 0.98.pl6.
Linux libc contains a
sysinfo() routine since 5.3.5, and
glibc has one since 1.90.


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