diff options
Diffstat (limited to 'arch/i386/kernel/timers/timer_tsc.c')
| -rw-r--r-- | arch/i386/kernel/timers/timer_tsc.c | 14 |
1 files changed, 12 insertions, 2 deletions
diff --git a/arch/i386/kernel/timers/timer_tsc.c b/arch/i386/kernel/timers/timer_tsc.c index 47675bbbb316..7c86e3c5f1c1 100644 --- a/arch/i386/kernel/timers/timer_tsc.c +++ b/arch/i386/kernel/timers/timer_tsc.c @@ -45,6 +45,15 @@ static unsigned long last_tsc_high; /* msb 32 bits of Time Stamp Counter */ static unsigned long long monotonic_base; static seqlock_t monotonic_lock = SEQLOCK_UNLOCKED; +/* Avoid compensating for lost ticks before TSCs are synched */ +static int detect_lost_ticks; +static int __init start_lost_tick_compensation(void) +{ + detect_lost_ticks = 1; + return 0; +} +late_initcall(start_lost_tick_compensation); + /* convert from cycles(64bits) => nanoseconds (64bits) * basic equation: * ns = cycles / (freq / ns_per_sec) @@ -196,7 +205,8 @@ static void mark_offset_tsc_hpet(void) /* lost tick compensation */ offset = hpet_readl(HPET_T0_CMP) - hpet_tick; - if (unlikely(((offset - hpet_last) > hpet_tick) && (hpet_last != 0))) { + if (unlikely(((offset - hpet_last) > hpet_tick) && (hpet_last != 0)) + && detect_lost_ticks) { int lost_ticks = (offset - hpet_last) / hpet_tick; jiffies_64 += lost_ticks; } @@ -421,7 +431,7 @@ static void mark_offset_tsc(void) delta += delay_at_last_interrupt; lost = delta/(1000000/HZ); delay = delta%(1000000/HZ); - if (lost >= 2) { + if (lost >= 2 && detect_lost_ticks) { jiffies_64 += lost-1; /* sanity check to ensure we're not always losing ticks */ |