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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | VERSIONS | CONFORMING TO | EXAMPLE | SEE ALSO | COLOPHON |
__PPC_GET_TIMEBASE(3) Linux Programmer'sManual __PPC_GET_TIMEBASE(3)
__ppc_get_timebase, __ppc_get_timebase_freq - get the current value
of the Time Base Register on Power architecture and its frequency.
#include <sys/platform/ppc.h>
uint64_t __ppc_get_timebase(void)
uint64_t __ppc_get_timebase_freq(void);
__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 Register 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.
__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.
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.
Both functions are nonstandard GNU extensions.
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);
}
time(2), usleep(3)
This page is part of release 4.12 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 2015-07-23 __PPC_GET_TIMEBASE(3)