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authorThomas Gleixner <tglx@linutronix.de>2007-02-16 01:27:43 -0800
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-02-16 08:13:57 -0800
commit5d8b34fdcb384161552d01ee8f34af5ff11f9684 (patch)
tree7052d50574d747b7ec2172051adf8126074d6982 /arch/i386
parent7e69f2b1ead2a4c51c12817f18263ff0e59335a6 (diff)
[PATCH] clocksource: Add verification (watchdog) helper
The TSC needs to be verified against another clocksource. Instead of using hardwired assumptions of available hardware, provide a generic verification mechanism. The verification uses the best available clocksource and handles the usability for high resolution timers / dynticks of the clocksource which needs to be verified. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@elte.hu> 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')
-rw-r--r--arch/i386/Kconfig4
-rw-r--r--arch/i386/kernel/tsc.c49
2 files changed, 4 insertions, 49 deletions
diff --git a/arch/i386/Kconfig b/arch/i386/Kconfig
index 4ea31c327d1..458b3aad3eb 100644
--- a/arch/i386/Kconfig
+++ b/arch/i386/Kconfig
@@ -18,6 +18,10 @@ config GENERIC_TIME
bool
default y
+config CLOCKSOURCE_WATCHDOG
+ bool
+ default y
+
config LOCKDEP_SUPPORT
bool
default y
diff --git a/arch/i386/kernel/tsc.c b/arch/i386/kernel/tsc.c
index b4b2be21d1c..22931d24027 100644
--- a/arch/i386/kernel/tsc.c
+++ b/arch/i386/kernel/tsc.c
@@ -344,49 +344,6 @@ static struct dmi_system_id __initdata bad_tsc_dmi_table[] = {
{}
};
-#define TSC_FREQ_CHECK_INTERVAL (10*MSEC_PER_SEC) /* 10sec in MS */
-static struct timer_list verify_tsc_freq_timer;
-
-/* XXX - Probably should add locking */
-static void verify_tsc_freq(unsigned long unused)
-{
- static u64 last_tsc;
- static unsigned long last_jiffies;
-
- u64 now_tsc, interval_tsc;
- unsigned long now_jiffies, interval_jiffies;
-
-
- if (check_tsc_unstable())
- return;
-
- rdtscll(now_tsc);
- now_jiffies = jiffies;
-
- if (!last_jiffies) {
- goto out;
- }
-
- interval_jiffies = now_jiffies - last_jiffies;
- interval_tsc = now_tsc - last_tsc;
- interval_tsc *= HZ;
- do_div(interval_tsc, cpu_khz*1000);
-
- if (interval_tsc < (interval_jiffies * 3 / 4)) {
- printk("TSC appears to be running slowly. "
- "Marking it as unstable\n");
- mark_tsc_unstable();
- return;
- }
-
-out:
- last_tsc = now_tsc;
- last_jiffies = now_jiffies;
- /* set us up to go off on the next interval: */
- mod_timer(&verify_tsc_freq_timer,
- jiffies + msecs_to_jiffies(TSC_FREQ_CHECK_INTERVAL));
-}
-
/*
* Make an educated guess if the TSC is trustworthy and synchronized
* over all CPUs.
@@ -424,12 +381,6 @@ static int __init init_tsc_clocksource(void)
clocksource_tsc.flags &= ~CLOCK_SOURCE_IS_CONTINUOUS;
}
- init_timer(&verify_tsc_freq_timer);
- verify_tsc_freq_timer.function = verify_tsc_freq;
- verify_tsc_freq_timer.expires =
- jiffies + msecs_to_jiffies(TSC_FREQ_CHECK_INTERVAL);
- add_timer(&verify_tsc_freq_timer);
-
return clocksource_register(&clocksource_tsc);
}