Ryujinx/Ryujinx.HLE/HOS/Kernel/Threading/KScheduler.cs
jhorv 5131b71437
Reducing memory allocations (#4537)
* add RecyclableMemoryStream dependency and MemoryStreamManager

* organize BinaryReader/BinaryWriter extensions

* add StreamExtensions to reduce need for BinaryWriter

* simple replacments of MemoryStream with RecyclableMemoryStream

* add write ReadOnlySequence<byte> support to IVirtualMemoryManager

* avoid 0-length array creation

* rework IpcMessage and related types to greatly reduce memory allocation by using RecylableMemoryStream, keeping streams around longer, avoiding their creation when possible, and avoiding creation of BinaryReader and BinaryWriter when possible

* reduce LINQ-induced memory allocations with custom methods to query KPriorityQueue

* use RecyclableMemoryStream in StreamUtils, and use StreamUtils in EmbeddedResources

* add constants for nanosecond/millisecond conversions

* code formatting

* XML doc adjustments

* fix: StreamExtension.WriteByte not writing non-zero values for lengths <= 16

* XML Doc improvements. Implement StreamExtensions.WriteByte() block writes for large-enough count values.

* add copyless path for StreamExtension.Write(ReadOnlySpan<int>)

* add default implementation of IVirtualMemoryManager.Write(ulong, ReadOnlySequence<byte>); remove previous explicit implementations

* code style fixes

* remove LINQ completely from KScheduler/KPriorityQueue by implementing a custom struct-based enumerator
2023-03-17 13:14:50 +01:00

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23 KiB
C#

using Ryujinx.Common;
using Ryujinx.HLE.HOS.Kernel.Process;
using System;
using System.Numerics;
using System.Threading;
namespace Ryujinx.HLE.HOS.Kernel.Threading
{
partial class KScheduler : IDisposable
{
public const int PrioritiesCount = 64;
public const int CpuCoresCount = 4;
private const int RoundRobinTimeQuantumMs = 10;
private static readonly int[] PreemptionPriorities = new int[] { 59, 59, 59, 63 };
private static readonly int[] _srcCoresHighestPrioThreads = new int[CpuCoresCount];
private readonly KernelContext _context;
private readonly int _coreId;
private struct SchedulingState
{
public volatile bool NeedsScheduling;
public volatile KThread SelectedThread;
}
private SchedulingState _state;
private AutoResetEvent _idleInterruptEvent;
private readonly object _idleInterruptEventLock;
private KThread _previousThread;
private KThread _currentThread;
private readonly KThread _idleThread;
public KThread PreviousThread => _previousThread;
public KThread CurrentThread => _currentThread;
public long LastContextSwitchTime { get; private set; }
public long TotalIdleTimeTicks => _idleThread.TotalTimeRunning;
public KScheduler(KernelContext context, int coreId)
{
_context = context;
_coreId = coreId;
_idleInterruptEvent = new AutoResetEvent(false);
_idleInterruptEventLock = new object();
KThread idleThread = CreateIdleThread(context, coreId);
_currentThread = idleThread;
_idleThread = idleThread;
idleThread.StartHostThread();
idleThread.SchedulerWaitEvent.Set();
}
private KThread CreateIdleThread(KernelContext context, int cpuCore)
{
KThread idleThread = new KThread(context);
idleThread.Initialize(0UL, 0UL, 0UL, PrioritiesCount, cpuCore, null, ThreadType.Dummy, IdleThreadLoop);
return idleThread;
}
public static ulong SelectThreads(KernelContext context)
{
if (context.ThreadReselectionRequested)
{
return SelectThreadsImpl(context);
}
else
{
return 0UL;
}
}
private static ulong SelectThreadsImpl(KernelContext context)
{
context.ThreadReselectionRequested = false;
ulong scheduledCoresMask = 0UL;
for (int core = 0; core < CpuCoresCount; core++)
{
KThread thread = context.PriorityQueue.ScheduledThreadsFirstOrDefault(core);
if (thread != null &&
thread.Owner != null &&
thread.Owner.PinnedThreads[core] != null &&
thread.Owner.PinnedThreads[core] != thread)
{
KThread candidate = thread.Owner.PinnedThreads[core];
if (candidate.KernelWaitersCount == 0 && !thread.Owner.IsExceptionUserThread(candidate))
{
if (candidate.SchedFlags == ThreadSchedState.Running)
{
thread = candidate;
}
else
{
thread = null;
}
}
}
scheduledCoresMask |= context.Schedulers[core].SelectThread(thread);
}
for (int core = 0; core < CpuCoresCount; core++)
{
// If the core is not idle (there's already a thread running on it),
// then we don't need to attempt load balancing.
if (context.PriorityQueue.HasScheduledThreads(core))
{
continue;
}
Array.Fill(_srcCoresHighestPrioThreads, 0);
int srcCoresHighestPrioThreadsCount = 0;
KThread dst = null;
// Select candidate threads that could run on this core.
// Give preference to threads that are not yet selected.
foreach (KThread suggested in context.PriorityQueue.SuggestedThreads(core))
{
if (suggested.ActiveCore < 0 || suggested != context.Schedulers[suggested.ActiveCore]._state.SelectedThread)
{
dst = suggested;
break;
}
_srcCoresHighestPrioThreads[srcCoresHighestPrioThreadsCount++] = suggested.ActiveCore;
}
// Not yet selected candidate found.
if (dst != null)
{
// Priorities < 2 are used for the kernel message dispatching
// threads, we should skip load balancing entirely.
if (dst.DynamicPriority >= 2)
{
context.PriorityQueue.TransferToCore(dst.DynamicPriority, core, dst);
scheduledCoresMask |= context.Schedulers[core].SelectThread(dst);
}
continue;
}
// All candidates are already selected, choose the best one
// (the first one that doesn't make the source core idle if moved).
for (int index = 0; index < srcCoresHighestPrioThreadsCount; index++)
{
int srcCore = _srcCoresHighestPrioThreads[index];
KThread src = context.PriorityQueue.ScheduledThreadsElementAtOrDefault(srcCore, 1);
if (src != null)
{
// Run the second thread on the queue on the source core,
// move the first one to the current core.
KThread origSelectedCoreSrc = context.Schedulers[srcCore]._state.SelectedThread;
scheduledCoresMask |= context.Schedulers[srcCore].SelectThread(src);
context.PriorityQueue.TransferToCore(origSelectedCoreSrc.DynamicPriority, core, origSelectedCoreSrc);
scheduledCoresMask |= context.Schedulers[core].SelectThread(origSelectedCoreSrc);
}
}
}
return scheduledCoresMask;
}
private ulong SelectThread(KThread nextThread)
{
KThread previousThread = _state.SelectedThread;
if (previousThread != nextThread)
{
if (previousThread != null)
{
previousThread.LastScheduledTime = PerformanceCounter.ElapsedTicks;
}
_state.SelectedThread = nextThread;
_state.NeedsScheduling = true;
return 1UL << _coreId;
}
else
{
return 0UL;
}
}
public static void EnableScheduling(KernelContext context, ulong scheduledCoresMask)
{
KScheduler currentScheduler = context.Schedulers[KernelStatic.GetCurrentThread().CurrentCore];
// Note that "RescheduleCurrentCore" will block, so "RescheduleOtherCores" must be done first.
currentScheduler.RescheduleOtherCores(scheduledCoresMask);
currentScheduler.RescheduleCurrentCore();
}
public static void EnableSchedulingFromForeignThread(KernelContext context, ulong scheduledCoresMask)
{
RescheduleOtherCores(context, scheduledCoresMask);
}
private void RescheduleCurrentCore()
{
if (_state.NeedsScheduling)
{
Schedule();
}
}
private void RescheduleOtherCores(ulong scheduledCoresMask)
{
RescheduleOtherCores(_context, scheduledCoresMask & ~(1UL << _coreId));
}
private static void RescheduleOtherCores(KernelContext context, ulong scheduledCoresMask)
{
while (scheduledCoresMask != 0)
{
int coreToSignal = BitOperations.TrailingZeroCount(scheduledCoresMask);
KThread threadToSignal = context.Schedulers[coreToSignal]._currentThread;
// Request the thread running on that core to stop and reschedule, if we have one.
if (threadToSignal != context.Schedulers[coreToSignal]._idleThread)
{
threadToSignal.Context.RequestInterrupt();
}
// If the core is idle, ensure that the idle thread is awaken.
context.Schedulers[coreToSignal]._idleInterruptEvent.Set();
scheduledCoresMask &= ~(1UL << coreToSignal);
}
}
private void IdleThreadLoop()
{
while (_context.Running)
{
_state.NeedsScheduling = false;
Thread.MemoryBarrier();
KThread nextThread = PickNextThread(_state.SelectedThread);
if (_idleThread != nextThread)
{
_idleThread.SchedulerWaitEvent.Reset();
WaitHandle.SignalAndWait(nextThread.SchedulerWaitEvent, _idleThread.SchedulerWaitEvent);
}
_idleInterruptEvent.WaitOne();
}
lock (_idleInterruptEventLock)
{
_idleInterruptEvent.Dispose();
_idleInterruptEvent = null;
}
}
public void Schedule()
{
_state.NeedsScheduling = false;
Thread.MemoryBarrier();
KThread currentThread = KernelStatic.GetCurrentThread();
KThread selectedThread = _state.SelectedThread;
// If the thread is already scheduled and running on the core, we have nothing to do.
if (currentThread == selectedThread)
{
return;
}
currentThread.SchedulerWaitEvent.Reset();
currentThread.ThreadContext.Unlock();
// Wake all the threads that might be waiting until this thread context is unlocked.
for (int core = 0; core < CpuCoresCount; core++)
{
_context.Schedulers[core]._idleInterruptEvent.Set();
}
KThread nextThread = PickNextThread(selectedThread);
if (currentThread.Context.Running)
{
// Wait until this thread is scheduled again, and allow the next thread to run.
WaitHandle.SignalAndWait(nextThread.SchedulerWaitEvent, currentThread.SchedulerWaitEvent);
}
else
{
// Allow the next thread to run.
nextThread.SchedulerWaitEvent.Set();
// We don't need to wait since the thread is exiting, however we need to
// make sure this thread will never call the scheduler again, since it is
// no longer assigned to a core.
currentThread.MakeUnschedulable();
// Just to be sure, set the core to a invalid value.
// This will trigger a exception if it attempts to call schedule again,
// rather than leaving the scheduler in a invalid state.
currentThread.CurrentCore = -1;
}
}
private KThread PickNextThread(KThread selectedThread)
{
while (true)
{
if (selectedThread != null)
{
// Try to run the selected thread.
// We need to acquire the context lock to be sure the thread is not
// already running on another core. If it is, then we return here
// and the caller should try again once there is something available for scheduling.
// The thread currently running on the core should have been requested to
// interrupt so this is not expected to take long.
// The idle thread must also be paused if we are scheduling a thread
// on the core, as the scheduled thread will handle the next switch.
if (selectedThread.ThreadContext.Lock())
{
SwitchTo(selectedThread);
if (!_state.NeedsScheduling)
{
return selectedThread;
}
selectedThread.ThreadContext.Unlock();
}
else
{
return _idleThread;
}
}
else
{
// The core is idle now, make sure that the idle thread can run
// and switch the core when a thread is available.
SwitchTo(null);
return _idleThread;
}
_state.NeedsScheduling = false;
Thread.MemoryBarrier();
selectedThread = _state.SelectedThread;
}
}
private void SwitchTo(KThread nextThread)
{
KProcess currentProcess = KernelStatic.GetCurrentProcess();
KThread currentThread = KernelStatic.GetCurrentThread();
nextThread ??= _idleThread;
if (currentThread != nextThread)
{
long previousTicks = LastContextSwitchTime;
long currentTicks = PerformanceCounter.ElapsedTicks;
long ticksDelta = currentTicks - previousTicks;
currentThread.AddCpuTime(ticksDelta);
if (currentProcess != null)
{
currentProcess.AddCpuTime(ticksDelta);
}
LastContextSwitchTime = currentTicks;
if (currentProcess != null)
{
_previousThread = !currentThread.TerminationRequested && currentThread.ActiveCore == _coreId ? currentThread : null;
}
else if (currentThread == _idleThread)
{
_previousThread = null;
}
}
if (nextThread.CurrentCore != _coreId)
{
nextThread.CurrentCore = _coreId;
}
_currentThread = nextThread;
}
public static void PreemptionThreadLoop(KernelContext context)
{
while (context.Running)
{
context.CriticalSection.Enter();
for (int core = 0; core < CpuCoresCount; core++)
{
RotateScheduledQueue(context, core, PreemptionPriorities[core]);
}
context.CriticalSection.Leave();
Thread.Sleep(RoundRobinTimeQuantumMs);
}
}
private static void RotateScheduledQueue(KernelContext context, int core, int prio)
{
KThread selectedThread = context.PriorityQueue.ScheduledThreadsWithDynamicPriorityFirstOrDefault(core, prio);
KThread nextThread = null;
// Yield priority queue.
if (selectedThread != null)
{
nextThread = context.PriorityQueue.Reschedule(prio, core, selectedThread);
}
static KThread FirstSuitableCandidateOrDefault(KernelContext context, int core, KThread selectedThread, KThread nextThread, Predicate< KThread> predicate)
{
foreach (KThread suggested in context.PriorityQueue.SuggestedThreads(core))
{
int suggestedCore = suggested.ActiveCore;
if (suggestedCore >= 0)
{
KThread selectedSuggestedCore = context.PriorityQueue.ScheduledThreadsFirstOrDefault(suggestedCore);
if (selectedSuggestedCore == suggested || (selectedSuggestedCore != null && selectedSuggestedCore.DynamicPriority < 2))
{
continue;
}
}
// If the candidate was scheduled after the current thread, then it's not worth it.
if (nextThread == selectedThread ||
nextThread == null ||
nextThread.LastScheduledTime >= suggested.LastScheduledTime)
{
if (predicate(suggested))
{
return suggested;
}
}
}
return null;
}
// Select candidate threads that could run on this core.
// Only take into account threads that are not yet selected.
KThread dst = FirstSuitableCandidateOrDefault(context, core, selectedThread, nextThread, x => x.DynamicPriority == prio);
if (dst != null)
{
context.PriorityQueue.TransferToCore(prio, core, dst);
}
// If the priority of the currently selected thread is lower or same as the preemption priority,
// then try to migrate a thread with lower priority.
KThread bestCandidate = context.PriorityQueue.ScheduledThreadsFirstOrDefault(core);
if (bestCandidate != null && bestCandidate.DynamicPriority >= prio)
{
dst = FirstSuitableCandidateOrDefault(context, core, selectedThread, nextThread, x => x.DynamicPriority < bestCandidate.DynamicPriority);
if (dst != null)
{
context.PriorityQueue.TransferToCore(dst.DynamicPriority, core, dst);
}
}
context.ThreadReselectionRequested = true;
}
public static void Yield(KernelContext context)
{
KThread currentThread = KernelStatic.GetCurrentThread();
if (!currentThread.IsSchedulable)
{
return;
}
context.CriticalSection.Enter();
if (currentThread.SchedFlags != ThreadSchedState.Running)
{
context.CriticalSection.Leave();
return;
}
KThread nextThread = context.PriorityQueue.Reschedule(currentThread.DynamicPriority, currentThread.ActiveCore, currentThread);
if (nextThread != currentThread)
{
context.ThreadReselectionRequested = true;
}
context.CriticalSection.Leave();
}
public static void YieldWithLoadBalancing(KernelContext context)
{
KThread currentThread = KernelStatic.GetCurrentThread();
if (!currentThread.IsSchedulable)
{
return;
}
context.CriticalSection.Enter();
if (currentThread.SchedFlags != ThreadSchedState.Running)
{
context.CriticalSection.Leave();
return;
}
int prio = currentThread.DynamicPriority;
int core = currentThread.ActiveCore;
// Move current thread to the end of the queue.
KThread nextThread = context.PriorityQueue.Reschedule(prio, core, currentThread);
static KThread FirstSuitableCandidateOrDefault(KernelContext context, int core, KThread nextThread, int lessThanOrEqualPriority)
{
foreach (KThread suggested in context.PriorityQueue.SuggestedThreads(core))
{
int suggestedCore = suggested.ActiveCore;
if (suggestedCore >= 0)
{
KThread selectedSuggestedCore = context.Schedulers[suggestedCore]._state.SelectedThread;
if (selectedSuggestedCore == suggested || (selectedSuggestedCore != null && selectedSuggestedCore.DynamicPriority < 2))
{
continue;
}
}
// If the candidate was scheduled after the current thread, then it's not worth it,
// unless the priority is higher than the current one.
if (suggested.LastScheduledTime <= nextThread.LastScheduledTime ||
suggested.DynamicPriority < nextThread.DynamicPriority)
{
if (suggested.DynamicPriority <= lessThanOrEqualPriority)
{
return suggested;
}
}
}
return null;
}
KThread dst = FirstSuitableCandidateOrDefault(context, core, nextThread, prio);
if (dst != null)
{
context.PriorityQueue.TransferToCore(dst.DynamicPriority, core, dst);
context.ThreadReselectionRequested = true;
}
else if (currentThread != nextThread)
{
context.ThreadReselectionRequested = true;
}
context.CriticalSection.Leave();
}
public static void YieldToAnyThread(KernelContext context)
{
KThread currentThread = KernelStatic.GetCurrentThread();
if (!currentThread.IsSchedulable)
{
return;
}
context.CriticalSection.Enter();
if (currentThread.SchedFlags != ThreadSchedState.Running)
{
context.CriticalSection.Leave();
return;
}
int core = currentThread.ActiveCore;
context.PriorityQueue.TransferToCore(currentThread.DynamicPriority, -1, currentThread);
if (!context.PriorityQueue.HasScheduledThreads(core))
{
KThread selectedThread = null;
foreach (KThread suggested in context.PriorityQueue.SuggestedThreads(core))
{
int suggestedCore = suggested.ActiveCore;
if (suggestedCore < 0)
{
continue;
}
KThread firstCandidate = context.PriorityQueue.ScheduledThreadsFirstOrDefault(suggestedCore);
if (firstCandidate == suggested)
{
continue;
}
if (firstCandidate == null || firstCandidate.DynamicPriority >= 2)
{
context.PriorityQueue.TransferToCore(suggested.DynamicPriority, core, suggested);
}
selectedThread = suggested;
break;
}
if (currentThread != selectedThread)
{
context.ThreadReselectionRequested = true;
}
}
else
{
context.ThreadReselectionRequested = true;
}
context.CriticalSection.Leave();
}
public void Dispose()
{
// Ensure that the idle thread is not blocked and can exit.
lock (_idleInterruptEventLock)
{
if (_idleInterruptEvent != null)
{
_idleInterruptEvent.Set();
}
}
}
}
}