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nptl: Remove pthread_clock_gettime pthread_clock_settime

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This patch removes CLOCK_THREAD_CPUTIME_ID and CLOCK_PROCESS_CPUTIME_ID support
from clock_gettime and clock_settime generic implementation.  For Linux, kernel
already provides supports through the syscall and Hurd HTL lacks
__pthread_clock_gettime and __pthread_clock_settime internal implementation.

As described in clock_gettime man-page [1] on 'Historical note for SMP
system', implementing CLOCK_{THREAD,PROCESS}_CPUTIME_ID with timer registers
is error-prone and susceptible to timing and accurary issues that the libc
can not deal without kernel support.

This allows removes unused code which, however, still incur in some runtime
overhead in thread creation (the struct pthread cpuclock_offset
initialization).

If hurd eventually wants to support them it should either either implement as
a kernel facility (or something related due its architecture) or in system
specific implementation.

Checked on aarch64-linux-gnu, x86_64-linux-gnu, and i686-linux-gnu. I also
checked on a i686-gnu build.

	* nptl/Makefile (libpthread-routines): Remove pthread_clock_gettime and
	pthread_clock_settime.
	* nptl/pthreadP.h (__find_thread_by_id): Remove prototype.
	* elf/dl-support.c [!HP_TIMING_NOAVAIL] (_dl_cpuclock_offset): Remove.
	(_dl_non_dynamic_init): Remove _dl_cpuclock_offset setting.
	* elf/rtld.c (_dl_start_final): Likewise.
	* nptl/allocatestack.c (__find_thread_by_id): Remove function.
	* sysdeps/generic/ldsodefs.h [!HP_TIMING_NOAVAIL] (_dl_cpuclock_offset):
	Remove.
	* sysdeps/mach/hurd/dl-sysdep.c [!HP_TIMING_NOAVAIL]
	(_dl_cpuclock_offset): Remove.
	* nptl/descr.h (struct pthread): Rename cpuclock_offset to
	cpuclock_offset_ununsed.
	* nptl/nptl-init.c (__pthread_initialize_minimal_internal): Remove
	cpuclock_offset set.
	* nptl/pthread_create.c (START_THREAD_DEFN): Likewise.
	* sysdeps/nptl/fork.c (__libc_fork): Likewise.
	* nptl/pthread_clock_gettime.c: Remove file.
	* nptl/pthread_clock_settime.c: Likewise.
	* sysdeps/unix/clock_gettime.c (hp_timing_gettime): Remove function.
	[HP_TIMING_AVAIL] (realtime_gettime): Remove CLOCK_THREAD_CPUTIME_ID
	and CLOCK_PROCESS_CPUTIME_ID support.
	* sysdeps/unix/clock_settime.c (hp_timing_gettime): Likewise.
	[HP_TIMING_AVAIL] (realtime_gettime): Likewise.
	* sysdeps/posix/clock_getres.c (hp_timing_getres): Likewise.
	[HP_TIMING_AVAIL] (__clock_getres): Likewise.
	* sysdeps/unix/clock_nanosleep.c (CPUCLOCK_P, INVALID_CLOCK_P):
	Likewise.
	(__clock_nanosleep): Remove CPUCLOCK_P and INVALID_CLOCK_P usage.

[1] http://man7.org/linux/man-pages/man2/clock_gettime.2.html
This commit is contained in:
Adhemerval Zanella
2019-01-16 16:22:29 +00:00
parent 421749d693
commit 38cc11daa4
18 changed files with 41 additions and 417 deletions
Download Patch File Download Diff File Expand all files Collapse all files

61
sysdeps/unix/clock_settime.c
View File

@@ -21,59 +21,11 @@
#include <ldsodefs.h>
#if HP_TIMING_AVAIL
/* Clock frequency of the processor. We make it a 64-bit variable
because some jokers are already playing with processors with more
than 4GHz. */
static hp_timing_t freq;
/* This function is defined in the thread library. */
extern void __pthread_clock_settime (clockid_t clock_id, hp_timing_t offset)
__attribute__ ((__weak__));
static int
hp_timing_settime (clockid_t clock_id, const struct timespec *tp)
{
hp_timing_t tsc;
hp_timing_t usertime;
/* First thing is to get the current time. */
HP_TIMING_NOW (tsc);
if (__glibc_unlikely (freq == 0))
{
/* This can only happen if we haven't initialized the `freq'
variable yet. Do this now. We don't have to protect this
code against multiple execution since all of them should lead
to the same result. */
freq = __get_clockfreq ();
if (__glibc_unlikely (freq == 0))
/* Something went wrong. */
return -1;
}
/* Convert the user-provided time into CPU ticks. */
usertime = tp->tv_sec * freq + (tp->tv_nsec * freq) / 1000000000ull;
/* Determine the offset and use it as the new base value. */
if (clock_id == CLOCK_PROCESS_CPUTIME_ID
|| __pthread_clock_settime == NULL)
GL(dl_cpuclock_offset) = tsc - usertime;
else
__pthread_clock_settime (clock_id, tsc - usertime);
return 0;
}
#endif
/* Set CLOCK to value TP. */
int
__clock_settime (clockid_t clock_id, const struct timespec *tp)
{
int retval;
int retval = -1;
/* Make sure the time cvalue is OK. */
if (tp->tv_nsec < 0 || tp->tv_nsec >= 1000000000)
@@ -93,16 +45,7 @@ __clock_settime (clockid_t clock_id, const struct timespec *tp)
break;
default:
# if HP_TIMING_AVAIL
if (CPUCLOCK_WHICH (clock_id) == CLOCK_PROCESS_CPUTIME_ID
|| CPUCLOCK_WHICH (clock_id) == CLOCK_THREAD_CPUTIME_ID)
retval = hp_timing_settime (clock_id, tp);
else
# endif
{
__set_errno (EINVAL);
retval = -1;
}
__set_errno (EINVAL);
break;
}