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__PPC_GET_TIMEBASE(3) - Linux man page online | Library functions

Get the current value.

Chapter
2017-09-15
__PPC_GET_TIMEBASE(3) Linux Programmer'sManual __PPC_GET_TIMEBASE(3)

NAME

__ppc_get_timebase, __ppc_get_timebase_freq - get the current value of the Time Base Register on Power architecture and its frequency.

SYNOPSIS

#include <sys/platform/ppc.h> uint64_t __ppc_get_timebase(void) uint64_t __ppc_get_timebase_freq(void);

DESCRIPTION

__ppc_get_timebase() reads the current value of the Time Base Register and returns its value, while __ppc_get_timebase_freq() returns the frequency in which the Time Base Regis‐ ter is updated. The Time Base Register is a 64-bit register provided by Power Architecture processors. It stores a monotonically incremented value that is updated at a system-dependent frequency that may be different from the processor frequency.

RETURN VALUE

__ppc_get_timebase() returns a 64-bit unsigned integer that represents the current value of the Time Base Register. __ppc_get_timebase_freq() returns a 64-bit unsigned integer that represents the frequency at which the Time Base Register is updated.

VERSIONS

GNU C Library support for __ppc_get_timebase() has been provided since version 2.16 and __ppc_get_timebase_freq() has been available since version 2.17.

CONFORMING TO

Both functions are nonstandard GNU extensions.

EXAMPLE

The following program will calculate the time, in microseconds, spent between two calls to __ppc_get_timebase(). Program source #include <inttypes.h> #include <stdint.h> #include <stdio.h> #include <stdlib.h> #include <sys/platform/ppc.h> /* Maximum value of the Time Base Register: 2^60 - 1. Source: POWER ISA. */ #define MAX_TB 0xFFFFFFFFFFFFFFF int main(void) { uint64_t tb1, tb2, diff; uint64_t freq = __ppc_get_timebase_freq(); printf("Time Base frequency = %"PRIu64" Hz\n", freq); tb1 = __ppc_get_timebase(); // Do some stuff... tb2 = __ppc_get_timebase(); if (tb2 > tb1) { diff = tb2 - tb1; } else { /* Treat Time Base Register overflow. */ diff = (MAX_TB - tb2) + tb1; } printf("Elapsed time = %1.2f usecs\n", (double) diff * 1000000 / freq ); exit(EXIT_SUCCESS); }

SEE ALSO

time(2), usleep(3)

COLOPHON

This page is part of release 4.15 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.
GNU C Library 2017-09-15 __PPC_GET_TIMEBASE(3)
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