diff options
Diffstat (limited to 'sysdeps/unix/i386')
| -rw-r--r-- | sysdeps/unix/i386/i586/Versions | 5 | ||||
| -rw-r--r-- | sysdeps/unix/i386/i586/clock_gettime.c | 47 | ||||
| -rw-r--r-- | sysdeps/unix/i386/i586/clock_settime.c | 85 | ||||
| -rw-r--r-- | sysdeps/unix/i386/i586/cpuclock-init.h | 27 |
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)) |