How to determine CPU and memory consumption from inside a process?

Question

I once had the task of determining the following performance parameters from inside a running application:

• Total virtual memory available
• Virtual memo

Answer 1

Linux

A portable way of reading memory and load numbers is the sysinfo call

Usage

   #include 

   int sysinfo(struct sysinfo *info);

DESCRIPTION

   Until Linux 2.3.16, sysinfo() used to return information in the
   following structure:

       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 to 64 bytes */
       };

   and the sizes are given as multiples of mem_unit bytes.