Content-type: text/html Man page of bind_to_cpu

bind_to_cpu

Section: C Library Functions (3)
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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

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 generated. A cpu_mask of zero clears any previously set CPU binding. 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) delim off


 

Index

NAME
LIBRARY
SYNOPSIS
PARAMETERS
DESCRIPTION
EXAMPLES
RETURN VALUES
RELATED INFORMATION

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Time: 02:42:31 GMT, October 02, 2010