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Kernel: Take into account the time keeper's frequency (if no HPET)

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The PIT is now also running at a rate of ~250 ticks/second, so rather
than assuming there are 1000 ticks/second we need to query the timer
being used for the actual frequency.

Fixes #4508
This commit is contained in:
Tom 2020-12-26 17:09:54 -07:00 committed by Andreas Kling
parent 0e2b7f9c9a
commit f1534ff36e
Notes: sideshowbarker 2024-07-19 00:34:17 +09:00 
Author: https://github.com/tomuta
Commit: https://github.com/SerenityOS/serenity/commit/f1534ff36e9
Pull-request: https://github.com/SerenityOS/serenity/pull/4562
Issue: https://github.com/SerenityOS/serenity/issues/4508
2 changed files with 7 additions and 3 deletions
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5
Kernel/Time/HardwareTimer.h
View file

@ -58,6 +58,7 @@ public:
virtual void set_periodic() = 0;
virtual void set_non_periodic() = 0;
virtual void disable() = 0;
virtual u32 frequency() const = 0;
virtual size_t ticks_per_second() const = 0;
@ -88,6 +89,8 @@ public:
return previous_callback;
}
virtual u32 frequency() const override { return (u32)m_frequency; }
protected:
HardwareTimer(u8 irq_number, Function<void(const RegisterState&)> callback = nullptr)
: IRQHandler(irq_number)
@ -131,6 +134,8 @@ public:
virtual const char* controller() const override { return nullptr; }
virtual bool eoi() override;
virtual u32 frequency() const override { return (u32)m_frequency; }
protected:
HardwareTimer(u8 irq_number, Function<void(const RegisterState&)> callback = nullptr)
: GenericInterruptHandler(irq_number)

5
Kernel/Time/TimeManagement.cpp
View file

@ -366,9 +366,8 @@ void TimeManagement::increment_time_since_boot()
// Compute time adjustment for adjtime. Let the clock run up to 1% fast or slow.
// That way, adjtime can adjust up to 36 seconds per hour, without time getting very jumpy.
// Once we have a smarter NTP service that also adjusts the frequency instead of just slewing time, maybe we can lower this.
constexpr long NanosPerTick = 1'000'000; // FIXME: Don't assume that one tick is 1 ms.
constexpr time_t MaxSlewNanos = NanosPerTick / 100;
static_assert(MaxSlewNanos < NanosPerTick);
long NanosPerTick = 1'000'000'000 / m_time_keeper_timer->frequency();
time_t MaxSlewNanos = NanosPerTick / 100;
u32 update_iteration = m_update1.fetch_add(1, AK::MemoryOrder::memory_order_acquire);