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Kernel: Allow parallel LAPIC timer initialization with HPET

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HPET supports reading LAPIC counter without locks, so it can be done in
parallel. This makes booting much faster. Previously initializing every
timer took 100 ms, so 16 CPUs took total of 1.6 seconds. This allows
doing it all in 100 ms.
This commit is contained in:
Bananymous
2024-09-19 14:41:59 +03:00
parent 8e08046519
commit a489be0e05
5 changed files with 27 additions and 13 deletions
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31
kernel/kernel/APIC.cpp
View File

@@ -253,11 +253,11 @@ namespace Kernel
const auto send_ipi =
[&](uint8_t processor, uint32_t data, uint64_t ud)
{
while ((read_from_local_apic(LAPIC_ICR_LO_REG) & ICR_LO_delivery_status_send_pending) == ICR_LO_delivery_status_send_pending)
__builtin_ia32_pause();
write_to_local_apic(LAPIC_ICR_HI_REG, (read_from_local_apic(LAPIC_ICR_HI_REG) & 0x00FFFFFF) | (processor << 24));
write_to_local_apic(LAPIC_ICR_LO_REG, data);
udelay(ud);
while ((read_from_local_apic(LAPIC_ICR_LO_REG) & ICR_LO_delivery_status_send_pending) == ICR_LO_delivery_status_send_pending)
__builtin_ia32_pause();
};
dprintln("System has {} processors", m_processors.size());
@@ -402,21 +402,26 @@ namespace Kernel
void APIC::initialize_timer()
{
{
constexpr uint64_t measuring_duration_ms = 100;
ASSERT(Kernel::Processor::get_interrupt_state() == InterruptState::Disabled);
SpinLockGuard _(s_timer_init_lock);
constexpr uint64_t measuring_duration_ms = 100;
write_to_local_apic(LAPIC_TIMER_LVT, TimerModeOneShot | TimerMask);
write_to_local_apic(LAPIC_TIMER_DIVIDE_REG, DivideBy2);
write_to_local_apic(LAPIC_TIMER_INITIAL_REG, 0xFFFFFFFF);
SystemTimer::get().pre_scheduler_sleep_ns(measuring_duration_ms * 1'000'000);
const bool needs_lock = SystemTimer::get().pre_scheduler_sleep_needs_lock();
if (needs_lock)
s_timer_init_lock.lock();
const uint32_t counter = read_from_local_apic(LAPIC_TIMER_CURRENT_REG);
m_lapic_timer_frequency_hz = static_cast<uint64_t>(0xFFFFFFFF - counter) * 2 * (1000 / measuring_duration_ms);
write_to_local_apic(LAPIC_TIMER_LVT, TimerModeOneShot | TimerMask);
write_to_local_apic(LAPIC_TIMER_DIVIDE_REG, DivideBy2);
write_to_local_apic(LAPIC_TIMER_INITIAL_REG, 0xFFFFFFFF);
SystemTimer::get().pre_scheduler_sleep_ns(measuring_duration_ms * 1'000'000);
dprintln("CPU {}: lapic timer frequency: {} Hz", Kernel::Processor::current_id(), m_lapic_timer_frequency_hz);
}
const uint32_t counter = read_from_local_apic(LAPIC_TIMER_CURRENT_REG);
m_lapic_timer_frequency_hz = static_cast<uint64_t>(0xFFFFFFFF - counter) * 2 * (1000 / measuring_duration_ms);
if (needs_lock)
s_timer_init_lock.unlock(InterruptState::Disabled);
dprintln("CPU {}: lapic timer frequency: {} Hz", Kernel::Processor::current_id(), m_lapic_timer_frequency_hz);
write_to_local_apic(LAPIC_TIMER_LVT, TimerModePeriodic | (IRQ_VECTOR_BASE + IRQ_TIMER));
write_to_local_apic(LAPIC_TIMER_INITIAL_REG, m_lapic_timer_frequency_hz / 2 / 100);

5
kernel/kernel/Timer/Timer.cpp
View File

@@ -69,6 +69,11 @@ namespace Kernel
return m_timer->time_since_boot();
}
bool SystemTimer::pre_scheduler_sleep_needs_lock() const
{
return m_timer->pre_scheduler_sleep_needs_lock();
}
void SystemTimer::pre_scheduler_sleep_ns(uint64_t ns)
{
return m_timer->pre_scheduler_sleep_ns(ns);