nptl: Remove pthread_clock_gettime pthread_clock_settime

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

View File

@ -1,3 +1,35 @@
2019-03-22 Adhemerval Zanella <adhemerval.zanella@linaro.org>
* 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.
2019-03-22 Stefan Liebler <stli@linux.ibm.com>
* sysdeps/s390/Makefile (sysdep_routines): Add memmem-arch13.

View File

@ -129,11 +129,6 @@ void *_dl_random;
#include <dl-procruntime.c>
#include <dl-procinfo.c>
/* Initial value of the CPU clock. */
#ifndef HP_TIMING_NONAVAIL
hp_timing_t _dl_cpuclock_offset;
#endif
void (*_dl_init_static_tls) (struct link_map *) = &_dl_nothread_init_static_tls;
size_t _dl_pagesize = EXEC_PAGESIZE;
@ -314,9 +309,6 @@ _dl_non_dynamic_init (void)
_dl_main_map.l_phdr = GL(dl_phdr);
_dl_main_map.l_phnum = GL(dl_phnum);
if (HP_SMALL_TIMING_AVAIL)
HP_TIMING_NOW (_dl_cpuclock_offset);
_dl_verbose = *(getenv ("LD_WARN") ?: "") == '\0' ? 0 : 1;
/* Set up the data structures for the system-supplied DSO early,

View File

@ -403,8 +403,6 @@ _dl_start_final (void *arg, struct dl_start_final_info *info)
# endif
#endif
HP_TIMING_NOW (GL(dl_cpuclock_offset));
/* Initialize the stack end variable. */
__libc_stack_end = __builtin_frame_address (0);

View File

@ -109,7 +109,6 @@ libpthread-routines = nptl-init nptlfreeres vars events version pt-interp \
pthread_once \
old_pthread_atfork \
pthread_getcpuclockid \
pthread_clock_gettime pthread_clock_settime \
shm-directory \
sem_init sem_destroy \
sem_open sem_close sem_unlink \

View File

@ -963,54 +963,6 @@ __reclaim_stacks (void)
}
#if HP_TIMING_AVAIL
# undef __find_thread_by_id
/* Find a thread given the thread ID. */
attribute_hidden
struct pthread *
__find_thread_by_id (pid_t tid)
{
struct pthread *result = NULL;
lll_lock (stack_cache_lock, LLL_PRIVATE);
/* Iterate over the list with system-allocated threads first. */
list_t *runp;
list_for_each (runp, &stack_used)
{
struct pthread *curp;
curp = list_entry (runp, struct pthread, list);
if (curp->tid == tid)
{
result = curp;
goto out;
}
}
/* Now the list with threads using user-allocated stacks. */
list_for_each (runp, &__stack_user)
{
struct pthread *curp;
curp = list_entry (runp, struct pthread, list);
if (curp->tid == tid)
{
result = curp;
goto out;
}
}
out:
lll_unlock (stack_cache_lock, LLL_PRIVATE);
return result;
}
#endif
#ifdef SIGSETXID
static void
setxid_mark_thread (struct xid_command *cmdp, struct pthread *t)

View File

@ -343,8 +343,7 @@ struct pthread
unsigned int setxid_futex;
#if HP_TIMING_AVAIL
/* Offset of the CPU clock at start thread start time. */
hp_timing_t cpuclock_offset;
hp_timing_t cpuclock_offset_ununsed;
#endif
/* If the thread waits to join another one the ID of the latter is

View File

@ -267,9 +267,6 @@ __pthread_initialize_minimal_internal (void)
THREAD_SETMEM (pd, user_stack, true);
if (LLL_LOCK_INITIALIZER != 0)
THREAD_SETMEM (pd, lock, LLL_LOCK_INITIALIZER);
#if HP_TIMING_AVAIL
THREAD_SETMEM (pd, cpuclock_offset, GL(dl_cpuclock_offset));
#endif
/* Initialize the robust mutex data. */
{

View File

@ -401,16 +401,6 @@ extern int __pthread_multiple_threads attribute_hidden;
extern int *__libc_multiple_threads_ptr attribute_hidden;
#endif
/* Find a thread given its TID. */
extern struct pthread *__find_thread_by_id (pid_t tid) attribute_hidden
#ifdef SHARED
;
#else
weak_function;
#define __find_thread_by_id(tid) \
(__find_thread_by_id ? (__find_thread_by_id) (tid) : (struct pthread *) NULL)
#endif
extern void __pthread_init_static_tls (struct link_map *) attribute_hidden;
extern size_t __pthread_get_minstack (const pthread_attr_t *attr);

View File

@ -1,67 +0,0 @@
/* Copyright (C) 2001-2019 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public License as
published by the Free Software Foundation; either version 2.1 of the
License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; see the file COPYING.LIB. If
not, see <http://www.gnu.org/licenses/>. */
#include <errno.h>
#include <stdlib.h>
#include <time.h>
#include "pthreadP.h"
#if HP_TIMING_AVAIL
int
__pthread_clock_gettime (clockid_t clock_id, hp_timing_t freq,
struct timespec *tp)
{
hp_timing_t tsc;
/* Get the current counter. */
HP_TIMING_NOW (tsc);
/* This is the ID of the thread we are looking for. */
pid_t tid = ((unsigned int) clock_id) >> CLOCK_IDFIELD_SIZE;
/* Compute the offset since the start time of the process. */
if (tid == 0 || tid == THREAD_GETMEM (THREAD_SELF, tid))
/* Our own clock. */
tsc -= THREAD_GETMEM (THREAD_SELF, cpuclock_offset);
else
{
/* This is more complicated. We have to locate the thread based
on the ID. This means walking the list of existing
threads. */
struct pthread *thread = __find_thread_by_id (tid);
if (thread == NULL)
{
__set_errno (EINVAL);
return -1;
}
/* There is a race here. The thread might terminate and the stack
become unusable. But this is the user's problem. */
tsc -= thread->cpuclock_offset;
}
/* Compute the seconds. */
tp->tv_sec = tsc / freq;
/* And the nanoseconds. This computation should be stable until
we get machines with about 16GHz frequency. */
tp->tv_nsec = ((tsc % freq) * 1000000000ull) / freq;
return 0;
}
#endif

View File

@ -1,54 +0,0 @@
/* Copyright (C) 2001-2019 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public License as
published by the Free Software Foundation; either version 2.1 of the
License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; see the file COPYING.LIB. If
not, see <http://www.gnu.org/licenses/>. */
#include <errno.h>
#include <stdlib.h>
#include <time.h>
#include "pthreadP.h"
#if HP_TIMING_AVAIL
int
__pthread_clock_settime (clockid_t clock_id, hp_timing_t offset)
{
/* This is the ID of the thread we are looking for. */
pid_t tid = ((unsigned int) clock_id) >> CLOCK_IDFIELD_SIZE;
/* Compute the offset since the start time of the process. */
if (tid == 0 || tid == THREAD_GETMEM (THREAD_SELF, tid))
/* Our own clock. */
THREAD_SETMEM (THREAD_SELF, cpuclock_offset, offset);
else
{
/* This is more complicated. We have to locate the thread based
on the ID. This means walking the list of existing
threads. */
struct pthread *thread = __find_thread_by_id (tid);
if (thread == NULL)
{
__set_errno (EINVAL);
return -1;
}
/* There is a race here. The thread might terminate and the stack
become unusable. But this is the user's problem. */
thread->cpuclock_offset = offset;
}
return 0;
}
#endif

View File

@ -379,13 +379,6 @@ START_THREAD_DEFN
{
struct pthread *pd = START_THREAD_SELF;
#if HP_TIMING_AVAIL
/* Remember the time when the thread was started. */
hp_timing_t now;
HP_TIMING_NOW (now);
THREAD_SETMEM (pd, cpuclock_offset, now);
#endif
/* Initialize resolver state pointer. */
__resp = &pd->res;

View File

@ -352,11 +352,6 @@ struct rtld_global
/* The object to be initialized first. */
EXTERN struct link_map *_dl_initfirst;
#if HP_SMALL_TIMING_AVAIL
/* Start time on CPU clock. */
EXTERN hp_timing_t _dl_cpuclock_offset;
#endif
/* Map of shared object to be profiled. */
EXTERN struct link_map *_dl_profile_map;

View File

@ -62,10 +62,6 @@ int __libc_multiple_libcs = 0; /* Defining this here avoids the inclusion
void *__libc_stack_end = NULL;
rtld_hidden_data_def(__libc_stack_end)
#if HP_TIMING_AVAIL
hp_timing_t _dl_cpuclock_offset;
#endif
/* TODO: Initialize. */
void *_dl_random attribute_relro = NULL;
@ -246,10 +242,6 @@ unfmh(); /* XXX */
/* Initialize frequently used global variable. */
GLRO(dl_pagesize) = __getpagesize ();
#if HP_TIMING_AVAIL
HP_TIMING_NOW (_dl_cpuclock_offset);
#endif
fmh(); /* XXX */
/* See hurd/hurdstartup.c; this deals with getting information

View File

@ -83,14 +83,6 @@ __libc_fork (void)
if (__fork_generation_pointer != NULL)
*__fork_generation_pointer += __PTHREAD_ONCE_FORK_GEN_INCR;
#if HP_TIMING_AVAIL
/* The CPU clock of the thread and process have to be set to zero. */
hp_timing_t now;
HP_TIMING_NOW (now);
THREAD_SETMEM (self, cpuclock_offset, now);
GL(dl_cpuclock_offset) = now;
#endif
#ifdef __NR_set_robust_list
/* Initialize the robust mutex list setting in the kernel which has
been reset during the fork. We do not check for errors because if

View File

@ -24,37 +24,6 @@
#include <libc-internal.h>
#if HP_TIMING_AVAIL
static long int nsec; /* Clock frequency of the processor. */
static int
hp_timing_getres (struct timespec *res)
{
if (__glibc_unlikely (nsec == 0))
{
hp_timing_t freq;
/* This can only happen if we haven't initialized the `nsec'
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;
nsec = MAX (UINT64_C (1000000000) / freq, 1);
}
/* Fill in the values.
The seconds are always zero (unless we have a 1Hz machine). */
res->tv_sec = 0;
res->tv_nsec = nsec;
return 0;
}
#endif
static inline int
realtime_getres (struct timespec *res)
{
@ -87,21 +56,8 @@ __clock_getres (clockid_t clock_id, struct timespec *res)
break;
default:
#if HP_TIMING_AVAIL
if ((clock_id & ((1 << CLOCK_IDFIELD_SIZE) - 1))
== CLOCK_THREAD_CPUTIME_ID)
retval = hp_timing_getres (res);
else
#endif
__set_errno (EINVAL);
__set_errno (EINVAL);
break;
#if HP_TIMING_AVAIL
case CLOCK_PROCESS_CPUTIME_ID:
case CLOCK_THREAD_CPUTIME_ID:
retval = hp_timing_getres (res);
break;
#endif
}
return retval;

View File

@ -24,57 +24,6 @@
#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 int __pthread_clock_gettime (clockid_t clock_id, hp_timing_t freq,
struct timespec *tp)
__attribute__ ((__weak__));
static int
hp_timing_gettime (clockid_t clock_id, struct timespec *tp)
{
hp_timing_t 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;
}
if (clock_id != CLOCK_PROCESS_CPUTIME_ID
&& __pthread_clock_gettime != NULL)
return __pthread_clock_gettime (clock_id, freq, tp);
/* Get the current counter. */
HP_TIMING_NOW (tsc);
/* Compute the offset since the start time of the process. */
tsc -= GL(dl_cpuclock_offset);
/* Compute the seconds. */
tp->tv_sec = tsc / freq;
/* And the nanoseconds. This computation should be stable until
we get machines with about 16GHz frequency. */
tp->tv_nsec = ((tsc % freq) * UINT64_C (1000000000)) / freq;
return 0;
}
#endif
static inline int
realtime_gettime (struct timespec *tp)
{
@ -105,20 +54,8 @@ __clock_gettime (clockid_t clock_id, struct timespec *tp)
break;
default:
#if HP_TIMING_AVAIL
if ((clock_id & ((1 << CLOCK_IDFIELD_SIZE) - 1))
== CLOCK_THREAD_CPUTIME_ID)
retval = hp_timing_gettime (clock_id, tp);
else
#endif
__set_errno (EINVAL);
__set_errno (EINVAL);
break;
#if HP_TIMING_AVAIL
case CLOCK_PROCESS_CPUTIME_ID:
retval = hp_timing_gettime (clock_id, tp);
break;
#endif
}
return retval;

View File

@ -19,23 +19,8 @@
#include <assert.h>
#include <errno.h>
#include <time.h>
#include <hp-timing.h>
#include <sysdep-cancel.h>
#if HP_TIMING_AVAIL
# define CPUCLOCK_P(clock) \
((clock) == CLOCK_PROCESS_CPUTIME_ID \
|| ((clock) & ((1 << CLOCK_IDFIELD_SIZE) - 1)) == CLOCK_THREAD_CPUTIME_ID)
#else
# define CPUCLOCK_P(clock) 0
#endif
#ifndef INVALID_CLOCK_P
# define INVALID_CLOCK_P(cl) \
((cl) < CLOCK_REALTIME || (cl) > CLOCK_THREAD_CPUTIME_ID)
#endif
/* This implementation assumes that these is only a `nanosleep' system
call. So we have to remap all other activities. */
int
@ -51,14 +36,7 @@ __clock_nanosleep (clockid_t clock_id, int flags, const struct timespec *req,
if (clock_id == CLOCK_THREAD_CPUTIME_ID)
return EINVAL; /* POSIX specifies EINVAL for this case. */
#ifdef SYSDEP_NANOSLEEP
SYSDEP_NANOSLEEP;
#endif
if (CPUCLOCK_P (clock_id))
return ENOTSUP;
if (INVALID_CLOCK_P (clock_id))
if (clock_id < CLOCK_REALTIME || clock_id > CLOCK_THREAD_CPUTIME_ID)
return EINVAL;
/* If we got an absolute time, remap it. */
@ -71,7 +49,7 @@ __clock_nanosleep (clockid_t clock_id, int flags, const struct timespec *req,
assert (sizeof (sec) >= sizeof (now.tv_sec));
/* Get the current time for this clock. */
if (__builtin_expect (__clock_gettime (clock_id, &now), 0) != 0)
if (__clock_gettime (clock_id, &now) != 0)
return errno;
/* Compute the difference. */
@ -90,12 +68,12 @@ __clock_nanosleep (clockid_t clock_id, int flags, const struct timespec *req,
/* Make sure we are not modifying the struct pointed to by REM. */
rem = NULL;
}
else if (__builtin_expect (flags, 0) != 0)
else if (flags != 0)
return EINVAL;
else if (clock_id != CLOCK_REALTIME)
/* Not supported. */
return ENOTSUP;
return __builtin_expect (__nanosleep (req, rem), 0) ? errno : 0;
return __nanosleep (req, rem), 0 ? errno : 0;
}
weak_alias (__clock_nanosleep, clock_nanosleep)

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;
}