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authorUlrich Drepper <drepper@redhat.com>2001-04-21 07:55:01 +0000
committerUlrich Drepper <drepper@redhat.com>2001-04-21 07:55:01 +0000
commit5fc48cd78f0c50e889d1c1f3b8f812058db71ecd (patch)
tree97c81fc8d9405b4f9228f2a76282017e887d8b13 /sysdeps/unix/i386
parentb17c0a8e31fe9e99359b6a874008de7aba85d64e (diff)
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Update.
2001-04-21 Ulrich Drepper <drepper@redhat.com> * elf/dl-support.c: Include cpuclock-init.h. Use CPUCLOCK_VARDEF and CPUCLOCK_INIT if defined. * sysdeps/generic/dl-sysdep.c: Likewise. * sysdeps/generic/cpuclock-init.h: New file. * sysdeps/unix/i386/i586/cpuclock-init.h: New file. * sysdeps/unix/i386/i586/Versions: New file. * sysdeps/unix/i386/i586/clock_settime.c: New file. * sysdeps/unix/i386/i586/clock_gettime.c: Handle thread CPU clock separately by calling __pthread_clock_gettime if this function is available. Subtract offset from tsc value before computing time value.
Diffstat (limited to 'sysdeps/unix/i386')
-rw-r--r--sysdeps/unix/i386/i586/Versions5
-rw-r--r--sysdeps/unix/i386/i586/clock_gettime.c47
-rw-r--r--sysdeps/unix/i386/i586/clock_settime.c85
-rw-r--r--sysdeps/unix/i386/i586/cpuclock-init.h27
4 files changed, 156 insertions, 8 deletions
diff --git a/sysdeps/unix/i386/i586/Versions b/sysdeps/unix/i386/i586/Versions
new file mode 100644
index 0000000000..4242ca448a
--- /dev/null
+++ b/sysdeps/unix/i386/i586/Versions
@@ -0,0 +1,5 @@
+ld {
+ GLIBC_2.2.3 {
+ _dl_cpuclock_offset;
+ }
+}
diff --git a/sysdeps/unix/i386/i586/clock_gettime.c b/sysdeps/unix/i386/i586/clock_gettime.c
index 85dcdcfe68..5e28370acf 100644
--- a/sysdeps/unix/i386/i586/clock_gettime.c
+++ b/sysdeps/unix/i386/i586/clock_gettime.c
@@ -19,6 +19,9 @@
#include <time.h>
#include <libc-internal.h>
+#include "cpuclock-init.h"
+
+
/* This implementation uses the TSC register in modern (i586 and up) IA-32
processors (most modern clones also provide it). Since we need the
resolution of the clock and since determining this is not cheap, we
@@ -33,17 +36,42 @@
static unsigned long long int freq;
-/* We add an limitation here: we assume that the machine is not up as
- long as it takes to wrap-around the 64-bit timestamp counter. On a
- 4GHz machine it would take 136 years of uptime to wrap around so
- this "limitation" is not severe.
+/* We need the starting time for the process. */
+CPUCLOCK_VARDECL (_dl_cpuclock_offset);
+
+
+/* This function is defined in the thread library. */
+extern int __pthread_clock_gettime (unsigned long long int freq,
+ struct timespec *tp)
+ __attribute__ ((__weak__));
+
- We use this clock also as the monotonic clock since we don't allow
- setting the CPU-time clock. If this should ever change we will have
- to separate the two. */
+/* We add an limitation here: we assume that the process is not
+ running as long as it takes to wrap-around the 64-bit timestamp
+ counter. On a 4GHz machine it would take 136 years of uptime to
+ wrap around so this "limitation" is not severe. */
#define EXTRA_CLOCK_CASES \
- case CLOCK_PROCESS_CPUTIME_ID: \
case CLOCK_THREAD_CPUTIME_ID: \
+ if (__pthread_clock_gettime != NULL) \
+ { \
+ if (__builtin_expect (freq == 0, 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 (__builtin_expect (freq == 0, 0)) \
+ /* Something went wrong. */ \
+ break; \
+ } \
+ \
+ retval = __pthread_clock_gettime (freq, tp); \
+ break; \
+ } \
+ /* FALLTHROUGH */ \
+ \
+ case CLOCK_PROCESS_CPUTIME_ID: \
{ \
unsigned long long int tsc; \
\
@@ -62,6 +90,9 @@ static unsigned long long int freq;
/* Get the current counter. */ \
asm volatile ("rdtsc" : "=A" (tsc)); \
\
+ /* Compute the offset since the start time of the process. */ \
+ tsc -= _dl_cpuclock_offset; \
+ \
/* Compute the seconds. */ \
tp->tv_sec = tsc / freq; \
\
diff --git a/sysdeps/unix/i386/i586/clock_settime.c b/sysdeps/unix/i386/i586/clock_settime.c
new file mode 100644
index 0000000000..465a68f694
--- /dev/null
+++ b/sysdeps/unix/i386/i586/clock_settime.c
@@ -0,0 +1,85 @@
+/* Copyright (C) 2001 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 Library General Public License as
+ published by the Free Software Foundation; either version 2 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
+ Library General Public License for more details.
+
+ You should have received a copy of the GNU Library General Public
+ License along with the GNU C Library; see the file COPYING.LIB. If not,
+ write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ Boston, MA 02111-1307, USA. */
+
+#include <time.h>
+
+#include "cpuclock-init.h"
+
+
+/* This implementation uses the TSC register in modern (i586 and up) IA-32
+ processors (most modern clones also provide it). Since we need the
+ resolution of the clock and since determining this is not cheap, we
+ cache the value. But this means that systems with processors running
+ at different speeds or process migration to machines with slower or
+ faster processors will not work without changes. */
+
+
+/* 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 unsigned long long int freq;
+
+
+/* We need the starting time for the process. */
+CPUCLOCK_VARDECL (_dl_cpuclock_offset);
+
+
+/* This function is defined in the thread library. */
+extern void __pthread_clock_settime (unsigned long long int offset)
+ __attribute__ ((__weak__));
+
+
+/* We add an limitation here: we assume that the process is not
+ running as long as it takes to wrap-around the 64-bit timestamp
+ counter. On a 4GHz machine it would take 136 years of uptime to
+ wrap around so this "limitation" is not severe. */
+#define EXTRA_CLOCK_CASES \
+ case CLOCK_PROCESS_CPUTIME_ID: \
+ case CLOCK_THREAD_CPUTIME_ID: \
+ { \
+ unsigned long long int tsc; \
+ unsigned long long int usertime; \
+ \
+ /* First thing is to get the current time. */ \
+ asm volatile ("rdtsc" : "=A" (tsc)); \
+ \
+ if (__builtin_expect (freq == 0, 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 (__builtin_expect (freq == 0, 0)) \
+ /* Something went wrong. */ \
+ break; \
+ } \
+ \
+ /* 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_THREAD_CPUTIME_ID \
+ || __pthread_clock_settime == NULL) \
+ _dl_cpuclock_offset = tsc - usertime; \
+ else \
+ __pthread_clock_settime (tsc - usertime); \
+ } \
+ break;
+
+#include <sysdeps/unix/clock_settime.c>
diff --git a/sysdeps/unix/i386/i586/cpuclock-init.h b/sysdeps/unix/i386/i586/cpuclock-init.h
new file mode 100644
index 0000000000..ff1ff9752a
--- /dev/null
+++ b/sysdeps/unix/i386/i586/cpuclock-init.h
@@ -0,0 +1,27 @@
+/* x86 TSC based CPU clock initialization code.
+ Copyright (C) 2001 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 Library General Public License as
+ published by the Free Software Foundation; either version 2 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
+ Library General Public License for more details.
+
+ You should have received a copy of the GNU Library General Public
+ License along with the GNU C Library; see the file COPYING.LIB. If not,
+ write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ Boston, MA 02111-1307, USA. */
+
+/* The TSC value has 64 bits. */
+#define CPUCLOCK_VARDEF(name) unsigned long long int name
+
+/* A declaration. */
+#define CPUCLOCK_VARDECL(name) extern unsigned long long int name
+
+/* Reading the TSC value is a simple instruction. */
+#define CPUCLOCK_INIT(name) asm volatile ("rdtsc" : "=A" (name))