diff options
| author | Ingo Molnar <mingo@elte.hu> | 2007-02-16 01:27:34 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-02-16 08:13:57 -0800 |
| commit | 95492e4646e5de8b43d9a7908d6177fb737b61f0 (patch) | |
| tree | ae25cd206ca76f78d50ac2a206ef012e0ab1d9df /include/asm-i386/tsc.h | |
| parent | 92c7e00254b2d0efc1e36ac3e45474ce1871b6b2 (diff) | |
[PATCH] x86: rewrite SMP TSC sync code
make the TSC synchronization code more robust, and unify it between x86_64 and
i386.
The biggest change is the removal of the 'fix up TSCs' code on x86_64 and
i386, in some rare cases it was /causing/ time-warps on SMP systems.
The new code only checks for TSC asynchronity - and if it can prove a
time-warp (if it can observe the TSC going backwards when going from one CPU
to another within a critical section), then the TSC clock-source is turned
off.
The TSC synchronization-checking code also got moved into a separate file.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/asm-i386/tsc.h')
| -rw-r--r-- | include/asm-i386/tsc.h | 49 |
1 files changed, 1 insertions, 48 deletions
diff --git a/include/asm-i386/tsc.h b/include/asm-i386/tsc.h index c13933185c1..e997891cc7c 100644 --- a/include/asm-i386/tsc.h +++ b/include/asm-i386/tsc.h @@ -1,48 +1 @@ -/* - * linux/include/asm-i386/tsc.h - * - * i386 TSC related functions - */ -#ifndef _ASM_i386_TSC_H -#define _ASM_i386_TSC_H - -#include <asm/processor.h> - -/* - * Standard way to access the cycle counter on i586+ CPUs. - * Currently only used on SMP. - * - * If you really have a SMP machine with i486 chips or older, - * compile for that, and this will just always return zero. - * That's ok, it just means that the nicer scheduling heuristics - * won't work for you. - * - * We only use the low 32 bits, and we'd simply better make sure - * that we reschedule before that wraps. Scheduling at least every - * four billion cycles just basically sounds like a good idea, - * regardless of how fast the machine is. - */ -typedef unsigned long long cycles_t; - -extern unsigned int cpu_khz; -extern unsigned int tsc_khz; - -static inline cycles_t get_cycles(void) -{ - unsigned long long ret = 0; - -#ifndef CONFIG_X86_TSC - if (!cpu_has_tsc) - return 0; -#endif - -#if defined(CONFIG_X86_GENERIC) || defined(CONFIG_X86_TSC) - rdtscll(ret); -#endif - return ret; -} - -extern void tsc_init(void); -extern void mark_tsc_unstable(void); - -#endif +#include <asm-x86_64/tsc.h> |