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 /arch/i386/kernel/tsc.c | |
| 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 'arch/i386/kernel/tsc.c')
| -rw-r--r-- | arch/i386/kernel/tsc.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/arch/i386/kernel/tsc.c b/arch/i386/kernel/tsc.c index 6f6971da761c..0fd93107ff9a 100644 --- a/arch/i386/kernel/tsc.c +++ b/arch/i386/kernel/tsc.c @@ -406,8 +406,10 @@ out: * Make an educated guess if the TSC is trustworthy and synchronized * over all CPUs. */ -static __init int unsynchronized_tsc(void) +__cpuinit int unsynchronized_tsc(void) { + if (!cpu_has_tsc || tsc_unstable) + return 1; /* * Intel systems are normally all synchronized. * Exceptions must mark TSC as unstable: |