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Core Timing: Rework Core Timing to run all cores evenly.

This commit is contained in:
Fernando Sahmkow 2019-09-09 21:37:29 -04:00 committed by FernandoS27
parent e664c24355
commit 555866f8dc
6 changed files with 89 additions and 38 deletions

View file

@ -116,7 +116,7 @@ public:
num_interpreted_instructions = 0;
}
u64 GetTicksRemaining() override {
return std::max(parent.system.CoreTiming().GetDowncount(), 0);
return std::max<s64>(parent.system.CoreTiming().GetDowncount(), 0LL);
}
u64 GetCNTPCT() override {
return Timing::CpuCyclesToClockCycles(parent.system.CoreTiming().GetTicks());

View file

@ -156,7 +156,7 @@ void ARM_Unicorn::Run() {
if (GDBStub::IsServerEnabled()) {
ExecuteInstructions(std::max(4000000, 0));
} else {
ExecuteInstructions(std::max(system.CoreTiming().GetDowncount(), 0));
ExecuteInstructions(std::max<s64>(system.CoreTiming().GetDowncount(), 0LL));
}
}

View file

@ -85,24 +85,16 @@ void Cpu::RunLoop(bool tight_loop) {
// instead advance to the next event and try to yield to the next thread
if (Kernel::GetCurrentThread() == nullptr) {
LOG_TRACE(Core, "Core-{} idling", core_index);
if (IsMainCore()) {
// TODO(Subv): Only let CoreTiming idle if all 4 cores are idling.
core_timing.Idle();
core_timing.Advance();
}
PrepareReschedule();
} else {
if (IsMainCore()) {
core_timing.Advance();
}
if (tight_loop) {
arm_interface->Run();
} else {
arm_interface->Step();
}
core_timing.Advance();
}
Reschedule();

View file

@ -15,7 +15,7 @@
namespace Core::Timing {
constexpr int MAX_SLICE_LENGTH = 20000;
constexpr int MAX_SLICE_LENGTH = 10000;
struct CoreTiming::Event {
s64 time;
@ -38,10 +38,14 @@ CoreTiming::CoreTiming() = default;
CoreTiming::~CoreTiming() = default;
void CoreTiming::Initialize() {
downcount = MAX_SLICE_LENGTH;
for (std::size_t core = 0; core < num_cpu_cores; core++) {
downcounts[core] = MAX_SLICE_LENGTH;
time_slice[core] = MAX_SLICE_LENGTH;
}
slice_length = MAX_SLICE_LENGTH;
global_timer = 0;
idled_cycles = 0;
current_context = 0;
// The time between CoreTiming being initialized and the first call to Advance() is considered
// the slice boundary between slice -1 and slice 0. Dispatcher loops must call Advance() before
@ -110,7 +114,7 @@ void CoreTiming::UnscheduleEvent(const EventType* event_type, u64 userdata) {
u64 CoreTiming::GetTicks() const {
u64 ticks = static_cast<u64>(global_timer);
if (!is_global_timer_sane) {
ticks += slice_length - downcount;
ticks += time_slice[current_context] - downcounts[current_context];
}
return ticks;
}
@ -120,7 +124,7 @@ u64 CoreTiming::GetIdleTicks() const {
}
void CoreTiming::AddTicks(u64 ticks) {
downcount -= static_cast<int>(ticks);
downcounts[current_context] -= static_cast<s64>(ticks);
}
void CoreTiming::ClearPendingEvents() {
@ -141,22 +145,36 @@ void CoreTiming::RemoveEvent(const EventType* event_type) {
void CoreTiming::ForceExceptionCheck(s64 cycles) {
cycles = std::max<s64>(0, cycles);
if (downcount <= cycles) {
if (downcounts[current_context] <= cycles) {
return;
}
// downcount is always (much) smaller than MAX_INT so we can safely cast cycles to an int
// here. Account for cycles already executed by adjusting the g.slice_length
slice_length -= downcount - static_cast<int>(cycles);
downcount = static_cast<int>(cycles);
slice_length -= downcounts[current_context] - static_cast<int>(cycles);
downcounts[current_context] = static_cast<int>(cycles);
}
std::optional<u64> CoreTiming::NextAvailableCore(const s64 needed_ticks) const {
const u64 original_context = current_context;
u64 next_context = (original_context + 1) % num_cpu_cores;
while (next_context != original_context) {
if (time_slice[next_context] >= needed_ticks) {
return {next_context};
} else if (time_slice[next_context] >= 0) {
return {};
}
next_context = (next_context + 1) % num_cpu_cores;
}
return {};
}
void CoreTiming::Advance() {
std::unique_lock<std::mutex> guard(inner_mutex);
const int cycles_executed = slice_length - downcount;
const int cycles_executed = time_slice[current_context] - downcounts[current_context];
time_slice[current_context] = std::max<s64>(0, downcounts[current_context]);
global_timer += cycles_executed;
slice_length = MAX_SLICE_LENGTH;
is_global_timer_sane = true;
@ -173,24 +191,40 @@ void CoreTiming::Advance() {
// Still events left (scheduled in the future)
if (!event_queue.empty()) {
slice_length = static_cast<int>(
std::min<s64>(event_queue.front().time - global_timer, MAX_SLICE_LENGTH));
s64 needed_ticks = std::min<s64>(event_queue.front().time - global_timer, MAX_SLICE_LENGTH);
const auto next_core = NextAvailableCore(needed_ticks);
if (next_core) {
downcounts[*next_core] = needed_ticks;
}
}
downcount = slice_length;
downcounts[current_context] = time_slice[current_context];
}
void CoreTiming::ResetRun() {
for (std::size_t core = 0; core < num_cpu_cores; core++) {
downcounts[core] = MAX_SLICE_LENGTH;
time_slice[core] = MAX_SLICE_LENGTH;
}
current_context = 0;
// Still events left (scheduled in the future)
if (!event_queue.empty()) {
s64 needed_ticks = std::min<s64>(event_queue.front().time - global_timer, MAX_SLICE_LENGTH);
downcounts[current_context] = needed_ticks;
}
}
void CoreTiming::Idle() {
idled_cycles += downcount;
downcount = 0;
idled_cycles += downcounts[current_context];
downcounts[current_context] = 0;
}
std::chrono::microseconds CoreTiming::GetGlobalTimeUs() const {
return std::chrono::microseconds{GetTicks() * 1000000 / BASE_CLOCK_RATE};
}
int CoreTiming::GetDowncount() const {
return downcount;
s64 CoreTiming::GetDowncount() const {
return downcounts[current_context];
}
} // namespace Core::Timing

View file

@ -7,6 +7,7 @@
#include <chrono>
#include <functional>
#include <mutex>
#include <optional>
#include <string>
#include <unordered_map>
#include <vector>
@ -104,7 +105,19 @@ public:
std::chrono::microseconds GetGlobalTimeUs() const;
int GetDowncount() const;
void ResetRun();
s64 GetDowncount() const;
void SwitchContext(u64 new_context) {
current_context = new_context;
}
bool CurrentContextCanRun() const {
return time_slice[current_context] > 0;
}
std::optional<u64> NextAvailableCore(const s64 needed_ticks) const;
private:
struct Event;
@ -112,10 +125,15 @@ private:
/// Clear all pending events. This should ONLY be done on exit.
void ClearPendingEvents();
static constexpr u64 num_cpu_cores = 4;
s64 global_timer = 0;
s64 idled_cycles = 0;
int slice_length = 0;
int downcount = 0;
s64 slice_length = 0;
std::array<s64, num_cpu_cores> downcounts{};
// Slice of time assigned to each core per run.
std::array<s64, num_cpu_cores> time_slice{};
u64 current_context = 0;
// Are we in a function that has been called from Advance()
// If events are scheduled from a function that gets called from Advance(),

View file

@ -6,6 +6,7 @@
#include "core/arm/exclusive_monitor.h"
#include "core/core.h"
#include "core/core_cpu.h"
#include "core/core_timing.h"
#include "core/cpu_core_manager.h"
#include "core/gdbstub/gdbstub.h"
#include "core/settings.h"
@ -122,13 +123,19 @@ void CpuCoreManager::RunLoop(bool tight_loop) {
}
}
auto& core_timing = system.CoreTiming();
core_timing.ResetRun();
bool keep_running{};
do {
keep_running = false;
for (active_core = 0; active_core < NUM_CPU_CORES; ++active_core) {
core_timing.SwitchContext(active_core);
if (core_timing.CurrentContextCanRun()) {
cores[active_core]->RunLoop(tight_loop);
if (Settings::values.use_multi_core) {
// Cores 1-3 are run on other threads in this mode
break;
}
keep_running |= core_timing.CurrentContextCanRun();
}
} while (keep_running);
if (GDBStub::IsServerEnabled()) {
GDBStub::SetCpuStepFlag(false);