bind_to_cpu man page on DigitalUNIX

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bind_to_cpu(3)							bind_to_cpu(3)

       bind_to_cpu, bind_to_cpu_id - Bind execution to a specific CPU

       #include	 <sys/types.h> #include <sys/resource.h> #include <sys/proces‐

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

       Mach Library (libmach.a)

       Specifies the target pid. You must  have	 access	 rights	 to  the  pid.
       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 gener‐
       ated. A cpu_mask of zero clears any previously set CPU binding.	Speci‐
       fies flags for the CPU binding.	Currently,  only  the  BIND_NO_INHERIT
       flag  is	 supported.  When  set,	 this  flag causes child processes and
       threads to not inherit the CPU binding.	Specifies the CPU on which the
       thread should run. The target CPU is the number of the CPU.

       Upon  return from bind_to_cpu() or bind_to_cpu_id(), all threads of the
       target pid are running on the target CPU. Bound threads are not	eligi‐
       ble for execution on any other CPU. You release CPU binding by invoking
       bind_to_cpu() with a cpu_mask of zero.

       Upon successful completion,  bind_to_cpu()  and	bind_to_cpu_id()  both
       return  zero. Upon error, a -1 is returned and errno is set to indicate
       the error.

       The operation did not have proper access permissions.  The call	passed
       an  invalid  argument.	The  specified	process or child process ID is
       invalid or not in use.

	* 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> #include <sys/processor.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,  sizeof(cpu_num),  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 identi‐
       fies the parent routine, the bind_to_cpu() routine is called. This rou‐
       tine  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() or bind_to_cpu_id() routine
       indicates an error, the parent process  kills  the  child  process  and
       exits with an error status.

       Commands: runon(1)

       Functions: getsysinfo(2)


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