From bb29ab26863c022743143f27956cc0ca362f258c Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Mon, 9 Jul 2007 18:51:59 +0200 Subject: sched: x86, track TSC-unstable events track TSC-unstable events and propagate it to the scheduler code. Also allow sched_clock() to be used when the TSC is unstable, the rq_clock() wrapper creates a reliable clock out of it. Signed-off-by: Ingo Molnar --- arch/i386/kernel/tsc.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) (limited to 'arch') diff --git a/arch/i386/kernel/tsc.c b/arch/i386/kernel/tsc.c index f64b81f3033b..ea63a30ca3e8 100644 --- a/arch/i386/kernel/tsc.c +++ b/arch/i386/kernel/tsc.c @@ -4,6 +4,7 @@ * See comments there for proper credits. */ +#include #include #include #include @@ -106,8 +107,13 @@ unsigned long long sched_clock(void) /* * Fall back to jiffies if there's no TSC available: + * ( But note that we still use it if the TSC is marked + * unstable. We do this because unlike Time Of Day, + * the scheduler clock tolerates small errors and it's + * very important for it to be as fast as the platform + * can achive it. ) */ - if (unlikely(!tsc_enabled)) + if (unlikely(!tsc_enabled && !tsc_unstable)) /* No locking but a rare wrong value is not a big deal: */ return (jiffies_64 - INITIAL_JIFFIES) * (1000000000 / HZ); @@ -277,6 +283,7 @@ static struct clocksource clocksource_tsc = { void mark_tsc_unstable(char *reason) { + sched_clock_unstable_event(); if (!tsc_unstable) { tsc_unstable = 1; tsc_enabled = 0; -- cgit v1.2.3-59-g8ed1b