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bind_to_cpu(3)
NAME
  bind_to_cpu - Bind execution to a specific CPU.

LIBRARY
  Mach Library (libmach.a)

SYNOPSIS
  #include <sys/types.h>
  #include <sys/resource.h>

  int bind_to_cpu(
	  pid_t pid,
	  unsigned long cpu_mask ,
	  unsigned long flag );

PARAMETERS
  pid	    Specifies the target pid.  You must have access rights to the
	    pid.

  cpu_mask  Specifies the CPU on which the thread should run. The target CPU
	    is the bit index in the mask.  If you set more than one bit, an
	    error is generated.	 A cpu_mask of zero clears any previously set
	    CPU binding.

  mask	    Specifies options to CPU binding.  Currently only the option
	    BIND_NO_INHERIT is supported.  When set, this option causes child
	    processes and threads to not inherit the CPU binding.

DESCRIPTION
  Upon return from bind_to_cpu, all threads of the target pid are running on
  the target CPU.  Bound threads are not eligible for execution on any other
  CPU. You release CPU binding by invoking bind_to_cpu with a  cpu_mask of
  zero.

EXAMPLES
       /*
	* Fork child process and force it to run on cpu number 3.
	* Processes created by the forked child will not inherit bindings.
	*/
       #include <sys/resource.h>
       #include <sys/sysinfo.h>
       #include <sys/signal.h>
       #include <sys/types.h>

       #define CPU_3   0x8	       /* Bit 3 set */

       main()
       {
	       pid_t pid;

	       if (pid = fork()) {     /* parent */
		       if (bind_to_cpu(pid, CPU_3, BIND_NO_INHERIT)) {
			       kill(pid, SIGKILL);
			       exit(1); /* bind_to_cpu() will print error msg */
		       }
		       sleep(2);       /*      wait for child to print CPU */
	       }
	       else {		       /* child */
		       long cpu_num;
		       sleep(1);       /*      wait for parent to bind CPU */
		       getsysinfo(GSI_CURRENT_CPU, &cpu_num, 0L, 0L, 0L);
		       printf("child running on CPU %d\n", cpu_num);
	       }
       }

  In this example, the CPU_3 symbol is defined so that bit three in the bit
  mask is set.	When the pid returned from the fork routine identifies the
  parent routine, the bind_to_cpu routine is called.  This routine binds the
  child process to CPU number three, as specified in the CPU_3 symbol. When
  the pid returned from the fork routine identifies the child routine, the
  child routine sleeps to give the parent routine time to set its CPU
  binding.  Then it uses the getsysinfo call to determine its CPU and
  displays its CPU with the printf routine.

  If the return value from the bind_to_cpu routine indicates an error, the
  parent process kills the child process and exits with an error status.

RETURN VALUES
  Upon successful completion, bind_to_cpu returns zero.	 Upon error, a -1 is
  returned.

RELATED INFORMATION
  Commands: runon(1)

  Functions: getsysinfo(2)

Index for Section 3

Alphabetical listing for B

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