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Kernel: Improve time keeping and dramatically reduce interrupt load

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This implements a number of changes related to time:
* If a HPET is present, it is now used only as a system timer, unless
  the Local APIC timer is used (in which case the HPET timer will not
  trigger any interrupts at all).
* If a HPET is present, the current time can now be as accurate as the
  chip can be, independently from the system timer. We now query the
  HPET main counter for the current time in CPU #0's system timer
  interrupt, and use that as a base line. If a high precision time is
  queried, that base line is used in combination with quering the HPET
  timer directly, which should give a much more accurate time stamp at
  the expense of more overhead. For faster time stamps, the more coarse
  value based on the last interrupt will be returned. This also means
  that any missed interrupts should not cause the time to drift.
* The default system interrupt rate is reduced to about 250 per second.
* Fix calculation of Thread CPU usage by using the amount of ticks they
  used rather than the number of times a context switch happened.
* Implement CLOCK_REALTIME_COARSE and CLOCK_MONOTONIC_COARSE and use it
  for most cases where precise timestamps are not needed.
This commit is contained in:
Tom 2020-12-03 22:12:50 -07:00 • committed by Andreas Kling
parent a3fdf5148b
commit 5f51d85184
32 changed files with 318 additions and 190 deletions
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19
Kernel/Thread.h
View file

@ -211,7 +211,7 @@ public:
: m_infinite(true)
{
}
explicit BlockTimeout(bool is_absolute, const timeval* time, const timespec* start_time = nullptr, clockid_t clock_id = CLOCK_MONOTONIC)
explicit BlockTimeout(bool is_absolute, const timeval* time, const timespec* start_time = nullptr, clockid_t clock_id = CLOCK_MONOTONIC_COARSE)
: m_clock_id(clock_id)
, m_infinite(!time)
{
@ -225,7 +225,7 @@ public:
timespec_add(m_time, m_start_time, m_time);
}
}
explicit BlockTimeout(bool is_absolute, const timespec* time, const timespec* start_time = nullptr, clockid_t clock_id = CLOCK_MONOTONIC)
explicit BlockTimeout(bool is_absolute, const timespec* time, const timespec* start_time = nullptr, clockid_t clock_id = CLOCK_MONOTONIC_COARSE)
: m_clock_id(clock_id)
, m_infinite(!time)
{
@ -249,7 +249,7 @@ public:
private:
timespec m_time { 0, 0 };
timespec m_start_time { 0, 0 };
clockid_t m_clock_id { CLOCK_MONOTONIC };
clockid_t m_clock_id { CLOCK_MONOTONIC_COARSE };
bool m_infinite { false };
bool m_should_block { false };
};
@ -756,7 +756,6 @@ public:
const TSS32& tss() const { return m_tss; }
State state() const { return m_state; }
const char* state_string() const;
u32 ticks() const { return m_ticks; }
VirtualAddress thread_specific_data() const { return m_thread_specific_data; }
size_t thread_specific_region_size() const { return m_thread_specific_region_size; }
@ -921,12 +920,12 @@ public:
BlockResult sleep(clockid_t, const timespec&, timespec* = nullptr);
BlockResult sleep(const timespec& duration, timespec* remaining_time = nullptr)
{
return sleep(CLOCK_MONOTONIC, duration, remaining_time);
return sleep(CLOCK_MONOTONIC_COARSE, duration, remaining_time);
}
BlockResult sleep_until(clockid_t, const timespec&);
BlockResult sleep_until(const timespec& duration)
{
return sleep_until(CLOCK_MONOTONIC, duration);
return sleep_until(CLOCK_MONOTONIC_COARSE, duration);
}
// Tell this thread to unblock if needed,
@ -937,7 +936,7 @@ public:
void exit(void* = nullptr);
bool tick();
bool tick(bool in_kernel);
void set_ticks_left(u32 t) { m_ticks_left = t; }
u32 ticks_left() const { return m_ticks_left; }
@ -1070,6 +1069,9 @@ public:
static constexpr u32 default_kernel_stack_size = 65536;
static constexpr u32 default_userspace_stack_size = 4 * MiB;
u32 ticks_in_user() const { return m_ticks_in_user; }
u32 ticks_in_kernel() const { return m_ticks_in_kernel; }
RecursiveSpinLock& get_lock() const { return m_lock; }
#ifdef LOCK_DEBUG
@ -1188,9 +1190,10 @@ private:
TSS32 m_tss;
Atomic<u32> m_cpu { 0 };
u32 m_cpu_affinity { THREAD_AFFINITY_DEFAULT };
u32 m_ticks { 0 };
u32 m_ticks_left { 0 };
u32 m_times_scheduled { 0 };
u32 m_ticks_in_user { 0 };
u32 m_ticks_in_kernel { 0 };
u32 m_pending_signals { 0 };
u32 m_signal_mask { 0 };
u32 m_kernel_stack_base { 0 };