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kernel/linux-rt-4.4.41/tools/testing/selftests/size/get_size.c 2.4 KB
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  /*
   * Copyright 2014 Sony Mobile Communications Inc.
   *
   * Licensed under the terms of the GNU GPL License version 2
   *
   * Selftest for runtime system size
   *
   * Prints the amount of RAM that the currently running system is using.
   *
   * This program tries to be as small as possible itself, to
   * avoid perturbing the system memory utilization with its
   * own execution.  It also attempts to have as few dependencies
   * on kernel features as possible.
   *
   * It should be statically linked, with startup libs avoided.
   * It uses no library calls, and only the following 3 syscalls:
   *   sysinfo(), write(), and _exit()
   *
   * For output, it avoids printf (which in some C libraries
   * has large external dependencies) by  implementing it's own
   * number output and print routines, and using __builtin_strlen()
   */
  
  #include <sys/sysinfo.h>
  #include <unistd.h>
  
  #define STDOUT_FILENO 1
  
  static int print(const char *s)
  {
  	return write(STDOUT_FILENO, s, __builtin_strlen(s));
  }
  
  static inline char *num_to_str(unsigned long num, char *buf, int len)
  {
  	unsigned int digit;
  
  	/* put digits in buffer from back to front */
  	buf += len - 1;
  	*buf = 0;
  	do {
  		digit = num % 10;
  		*(--buf) = digit + '0';
  		num /= 10;
  	} while (num > 0);
  
  	return buf;
  }
  
  static int print_num(unsigned long num)
  {
  	char num_buf[30];
  
  	return print(num_to_str(num, num_buf, sizeof(num_buf)));
  }
  
  static int print_k_value(const char *s, unsigned long num, unsigned long units)
  {
  	unsigned long long temp;
  	int ccode;
  
  	print(s);
  
  	temp = num;
  	temp = (temp * units)/1024;
  	num = temp;
  	ccode = print_num(num);
  	print("
  ");
  	return ccode;
  }
  
  /* this program has no main(), as startup libraries are not used */
  void _start(void)
  {
  	int ccode;
  	struct sysinfo info;
  	unsigned long used;
  
  	print("Testing system size.
  ");
  	print("1..1
  ");
  
  	ccode = sysinfo(&info);
  	if (ccode < 0) {
  		print("not ok 1 get runtime memory use
  ");
  		print("# could not get sysinfo
  ");
  		_exit(ccode);
  	}
  	/* ignore cache complexities for now */
  	used = info.totalram - info.freeram - info.bufferram;
  	print_k_value("ok 1 get runtime memory use # size = ", used,
  		info.mem_unit);
  
  	print("# System runtime memory report (units in Kilobytes):
  ");
  	print_k_value("#   Total:  ", info.totalram, info.mem_unit);
  	print_k_value("#   Free:   ", info.freeram, info.mem_unit);
  	print_k_value("#   Buffer: ", info.bufferram, info.mem_unit);
  	print_k_value("#   In use: ", used, info.mem_unit);
  
  	_exit(0);
  }