Ryujinx/Ryujinx.HLE/HOS/Kernel/Threading/KScheduler.cs

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using Ryujinx.HLE.HOS.Kernel.Process;
using System;
using System.Collections.Generic;
using System.Linq;
namespace Ryujinx.HLE.HOS.Kernel.Threading
{
partial class KScheduler : IDisposable
{
public const int PrioritiesCount = 64;
public const int CpuCoresCount = 4;
private const int PreemptionPriorityCores012 = 59;
private const int PreemptionPriorityCore3 = 63;
private Horizon _system;
public KSchedulingData SchedulingData { get; private set; }
public KCoreContext[] CoreContexts { get; private set; }
public bool ThreadReselectionRequested { get; set; }
public KScheduler(Horizon system)
{
_system = system;
SchedulingData = new KSchedulingData();
CoreManager = new HleCoreManager();
CoreContexts = new KCoreContext[CpuCoresCount];
for (int core = 0; core < CpuCoresCount; core++)
{
CoreContexts[core] = new KCoreContext(this, CoreManager);
}
}
private void PreemptThreads()
{
_system.CriticalSection.Enter();
PreemptThread(PreemptionPriorityCores012, 0);
PreemptThread(PreemptionPriorityCores012, 1);
PreemptThread(PreemptionPriorityCores012, 2);
PreemptThread(PreemptionPriorityCore3, 3);
_system.CriticalSection.Leave();
}
private void PreemptThread(int prio, int core)
{
IEnumerable<KThread> scheduledThreads = SchedulingData.ScheduledThreads(core);
KThread selectedThread = scheduledThreads.FirstOrDefault(x => x.DynamicPriority == prio);
//Yield priority queue.
if (selectedThread != null)
{
SchedulingData.Reschedule(prio, core, selectedThread);
}
IEnumerable<KThread> SuitableCandidates()
{
foreach (KThread thread in SchedulingData.SuggestedThreads(core))
{
int srcCore = thread.CurrentCore;
if (srcCore >= 0)
{
KThread highestPrioSrcCore = SchedulingData.ScheduledThreads(srcCore).FirstOrDefault();
if (highestPrioSrcCore != null && highestPrioSrcCore.DynamicPriority < 2)
{
break;
}
if (highestPrioSrcCore == thread)
{
continue;
}
}
//If the candidate was scheduled after the current thread, then it's not worth it.
if (selectedThread == null || selectedThread.LastScheduledTime >= thread.LastScheduledTime)
{
yield return thread;
}
}
}
//Select candidate threads that could run on this core.
//Only take into account threads that are not yet selected.
KThread dst = SuitableCandidates().FirstOrDefault(x => x.DynamicPriority == prio);
if (dst != null)
{
SchedulingData.TransferToCore(prio, core, dst);
selectedThread = dst;
}
//If the priority of the currently selected thread is lower than preemption priority,
//then allow threads with lower priorities to be selected aswell.
if (selectedThread != null && selectedThread.DynamicPriority > prio)
{
Func<KThread, bool> predicate = x => x.DynamicPriority >= selectedThread.DynamicPriority;
dst = SuitableCandidates().FirstOrDefault(predicate);
if (dst != null)
{
SchedulingData.TransferToCore(dst.DynamicPriority, core, dst);
}
}
ThreadReselectionRequested = true;
}
public void SelectThreads()
{
ThreadReselectionRequested = false;
for (int core = 0; core < CpuCoresCount; core++)
{
KThread thread = SchedulingData.ScheduledThreads(core).FirstOrDefault();
CoreContexts[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 (SchedulingData.ScheduledThreads(core).Any())
{
continue;
}
int[] srcCoresHighestPrioThreads = new int[CpuCoresCount];
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 thread in SchedulingData.SuggestedThreads(core))
{
if (thread.CurrentCore < 0 || thread != CoreContexts[thread.CurrentCore].SelectedThread)
{
dst = thread;
break;
}
srcCoresHighestPrioThreads[srcCoresHighestPrioThreadsCount++] = thread.CurrentCore;
}
//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)
{
SchedulingData.TransferToCore(dst.DynamicPriority, core, dst);
CoreContexts[core].SelectThread(dst);
}
continue;
}
//All candiates 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 = SchedulingData.ScheduledThreads(srcCore).ElementAtOrDefault(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 = CoreContexts[srcCore].SelectedThread;
CoreContexts[srcCore].SelectThread(src);
SchedulingData.TransferToCore(origSelectedCoreSrc.DynamicPriority, core, origSelectedCoreSrc);
CoreContexts[core].SelectThread(origSelectedCoreSrc);
}
}
}
}
public KThread GetCurrentThread()
{
lock (CoreContexts)
{
for (int core = 0; core < CpuCoresCount; core++)
{
if (CoreContexts[core].CurrentThread?.Context.IsCurrentThread() ?? false)
{
return CoreContexts[core].CurrentThread;
}
}
}
return GetDummyThread();
throw new InvalidOperationException("Current thread is not scheduled!");
}
private KThread _dummyThread;
private KThread GetDummyThread()
{
if (_dummyThread != null)
{
return _dummyThread;
}
KProcess dummyProcess = new KProcess(_system);
KThread dummyThread = new KThread(_system);
dummyThread.Initialize(0, 0, 0, 44, 0, dummyProcess, ThreadType.Dummy);
return _dummyThread = dummyThread;
}
public KProcess GetCurrentProcess()
{
return GetCurrentThread().Owner;
}
public void Dispose()
{
Dispose(true);
}
protected virtual void Dispose(bool disposing)
{
if (disposing)
{
_keepPreempting = false;
}
}
}
}