GPU logic updated to use prime % divisor result precomputed on CPU instead of re-calculating it on GPU side. Cycle lease removed.

PerfectNumbers.Core/DivisorCycleCache.cs

@@ -12,60 +12,15 @@ namespace PerfectNumbers.Core;
 
 public sealed class DivisorCycleCache
 {
-    internal sealed class CycleBlock
+    public sealed class CycleBlock(int index, ulong start, ulong[] cycles)
 	{
-        internal CycleBlock(int index, ulong start, ulong[] cycles)
+		internal readonly int Index = index;
-        {
+		internal readonly ulong Start = start;
-            Index = index;
+		internal readonly ulong End = start + (ulong)cycles.Length - 1UL;
-            Start = start;
+		internal readonly ulong[] Cycles = cycles;
-            Cycles = cycles;
-            End = start + (ulong)cycles.Length - 1UL;
-        }
-
-        internal int Index { get; }
-
-        internal ulong Start { get; }
-
-        internal ulong End { get; }
-
-        internal ulong[] Cycles { get; }
 
 		[MethodImpl(MethodImplOptions.AggressiveInlining)]
-        internal ulong GetCycle(ulong divisor)
+		public ulong GetCycle(ulong divisor) => Cycles[(int)(divisor - Start)];
-        {
-            if (divisor < Start || divisor > End)
-            {
-                return 0UL;
-            }
-
-            return Cycles[(int)(divisor - Start)];
-        }
-    }
-
-    public struct Lease : IDisposable
-    {
-        private CycleBlock? _block;
-
-        internal Lease(CycleBlock block)
-        {
-            _block = block;
-        }
-
-        public readonly bool IsValid => _block is not null;
-
-        public readonly ulong Start => _block?.Start ?? 0UL;
-
-        public readonly ulong End => _block?.End ?? 0UL;
-
-        public readonly ulong[]? Values => _block?.Cycles;
-
-        [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public readonly ulong GetCycle(ulong divisor) => _block?.GetCycle(divisor) ?? 0UL;
-
-        public void Dispose()
-        {
-            _block = null;
-        }
 	}
 
     private const int CycleGenerationBatchSize = 262_144;
@@ -115,15 +70,14 @@ public sealed class DivisorCycleCache
         }
     }
 
-    public Lease Acquire(ulong divisor)
+    public CycleBlock Acquire(ulong divisor)
     {
         if (divisor <= _baseBlock.End)
         {
-            return new Lease(_baseBlock);
+            return _baseBlock;
         }
 
-        CycleBlock block = AcquireDynamicBlock(divisor);
+        return AcquireDynamicBlock(divisor);
-        return new Lease(block);
     }
 
     private CycleBlock AcquireDynamicBlock(ulong divisor)

PerfectNumbers.Core/Gpu/MersenneNumberDivisorByDivisorGpuTester.cs

@@ -25,14 +25,14 @@ public sealed class MersenneNumberDivisorByDivisorGpuTester : IMersenneNumberDiv
 		public readonly ulong MontgomeryTwo = montgomeryTwo;
 	}
 
-    private readonly ConcurrentDictionary<Accelerator, Action<Index1D, ulong, byte, ArrayView<MontgomeryDivisorData>, ArrayView<byte>>> _kernelCache = new();
+	private readonly ConcurrentDictionary<Accelerator, Action<Index1D, ulong, byte, ulong, ArrayView<MontgomeryDivisorData>, ArrayView<byte>>> _kernelCache = new();
 	private readonly ConcurrentDictionary<Accelerator, Action<Index1D, MontgomeryDivisorData, ArrayView<ulong>, ArrayView<ulong>>> _kernelExponentCache = new();
 	private readonly ConcurrentDictionary<Accelerator, ConcurrentBag<BatchResources>> _resourcePools = new(AcceleratorReferenceComparer.Instance);
 	private readonly ConcurrentDictionary<Accelerator, Action<Index1D, ulong, ArrayView<ulong>, ArrayView<byte>>> _cycleKernelCache = new();
 	private readonly ConcurrentBag<DivisorScanSession> _sessionPool = new();
 
-    private Action<Index1D, ulong, byte, ArrayView<MontgomeryDivisorData>, ArrayView<byte>> GetKernel(Accelerator accelerator) =>
+	private Action<Index1D, ulong, byte, ulong, ArrayView<MontgomeryDivisorData>, ArrayView<byte>> GetKernel(Accelerator accelerator) =>
-                                                                    _kernelCache.GetOrAdd(accelerator, acc => acc.LoadAutoGroupedStreamKernel<Index1D, ulong, byte, ArrayView<MontgomeryDivisorData>, ArrayView<byte>>(CheckKernel));
+																	_kernelCache.GetOrAdd(accelerator, acc => acc.LoadAutoGroupedStreamKernel<Index1D, ulong, byte, ulong, ArrayView<MontgomeryDivisorData>, ArrayView<byte>>(CheckKernel));
 	private Action<Index1D, MontgomeryDivisorData, ArrayView<ulong>, ArrayView<ulong>> GetKernelByPrimeExponent(Accelerator accelerator) =>
 																														  _kernelExponentCache.GetOrAdd(accelerator, acc => acc.LoadAutoGroupedStreamKernel<Index1D, MontgomeryDivisorData, ArrayView<ulong>, ArrayView<ulong>>(ComputePrimeExponentKernel));
 	private Action<Index1D, ulong, ArrayView<ulong>, ArrayView<byte>> GetCycleKernel(Accelerator accelerator) =>
@@ -138,7 +138,7 @@ public sealed class MersenneNumberDivisorByDivisorGpuTester : IMersenneNumberDiv
 			ulong allowedMax,
 			bool useCycles,
 			Accelerator accelerator,
-                        Action<Index1D, ulong, byte, ArrayView<MontgomeryDivisorData>, ArrayView<byte>> kernel,
+			Action<Index1D, ulong, byte, ulong, ArrayView<MontgomeryDivisorData>, ArrayView<byte>> kernel,
 			MemoryBuffer1D<MontgomeryDivisorData, Stride1D.Dense> divisorsBuffer,
 			MemoryBuffer1D<byte, Stride1D.Dense> hitsBuffer,
 			ulong[] divisors,
@@ -161,10 +161,9 @@ public sealed class MersenneNumberDivisorByDivisorGpuTester : IMersenneNumberDiv
 
 		bool composite = false;
 		bool processedAll = false;
-        ulong currentDivisor, divisor = 3UL, next, nextDivisor;
+		ulong currentDivisor = 3UL, cycle = 0UL, next, nextDivisor;
 		int batchSize, i;
 		bool reachedEndInBatch;
-        bool requiresCycleKernelCheck;
 
 		Span<MontgomeryDivisorData> divisorDataSpan;
 		Span<ulong> divisorSpan;
@@ -172,34 +171,31 @@ public sealed class MersenneNumberDivisorByDivisorGpuTester : IMersenneNumberDiv
 		ArrayView1D<MontgomeryDivisorData, Stride1D.Dense> divisorView;
 		ArrayView1D<byte, Stride1D.Dense> hitsView;
 		DivisorCycleCache divisorCyclesCache = DivisorCycleCache.Shared;
+		DivisorCycleCache.CycleBlock? cycleLease = useCycles ? divisorCyclesCache.Acquire(currentDivisor) : null;
 
-        while (divisor <= allowedMax)
+		while (currentDivisor <= allowedMax)
 		{
 			batchSize = 0;
 			reachedEndInBatch = false;
-            requiresCycleKernelCheck = false;
 
-            while (batchSize < batchCapacity && divisor <= allowedMax)
+			while (batchSize < batchCapacity && currentDivisor <= allowedMax)
 			{
-                currentDivisor = divisor;
 				nextDivisor = currentDivisor + 2UL;
 				processedCount++;
 
 				bool includeDivisor = true;
 				if (useCycles)
 				{
-					DivisorCycleCache.Lease cycleLease = divisorCyclesCache.Acquire(currentDivisor);
+					if (currentDivisor > cycleLease!.End)
-					ulong cycle = cycleLease.GetCycle(currentDivisor);
-					if (cycle == 0UL)
 					{
-						requiresCycleKernelCheck = true;
+						cycleLease = divisorCyclesCache.Acquire(currentDivisor);
 					}
-					else if (prime % cycle != 0UL)
+
+					cycle = prime % cycleLease.GetCycle(currentDivisor);
+					if (cycle != 0UL)
 					{
 						includeDivisor = false;
 					}
-
-					cycleLease.Dispose();
 				}
 
 				if (includeDivisor)
@@ -210,7 +206,7 @@ public sealed class MersenneNumberDivisorByDivisorGpuTester : IMersenneNumberDiv
 				lastProcessed = currentDivisor;
 				next = nextDivisor;
 
-                if (next <= divisor)
+				if (next <= currentDivisor)
 				{
 					reachedEndInBatch = true;
 					break;
@@ -218,12 +214,12 @@ public sealed class MersenneNumberDivisorByDivisorGpuTester : IMersenneNumberDiv
 
 				if (next > allowedMax)
 				{
-                    divisor = next;
+					currentDivisor = next;
 					reachedEndInBatch = true;
 					break;
 				}
 
-                divisor = next;
+				currentDivisor = next;
 			}
 
 			if (batchSize == 0)
@@ -250,8 +246,8 @@ public sealed class MersenneNumberDivisorByDivisorGpuTester : IMersenneNumberDiv
 			}
 
 			divisorView.CopyFromCPU(ref MemoryMarshal.GetReference(divisorDataSpan), batchSize);
-            byte useCycleChecks = useCycles && requiresCycleKernelCheck ? (byte)1 : (byte)0;
+			byte useCycleChecks = useCycles ? (byte)1 : (byte)0;
-            kernel(batchSize, prime, useCycleChecks, divisorView, hitsView);
+			kernel(batchSize, prime, useCycleChecks, cycle, divisorView, hitsView);
 			accelerator.Synchronize();
 			hitsView.CopyToCPU(ref MemoryMarshal.GetReference(hitsSpan), batchSize);
 
@@ -281,7 +277,7 @@ public sealed class MersenneNumberDivisorByDivisorGpuTester : IMersenneNumberDiv
 			}
 		}
 
-        coveredRange = composite || processedAll || divisor > allowedMax;
+		coveredRange = composite || processedAll || currentDivisor > allowedMax;
 
 		return composite;
 	}
@@ -316,7 +312,7 @@ public sealed class MersenneNumberDivisorByDivisorGpuTester : IMersenneNumberDiv
 		return Math.Min((1UL << (int)(prime - 1UL)) - 1UL, divisorLimit);
 	}
 
-    private static void CheckKernel(Index1D index, ulong prime, byte useCycleChecks, ArrayView<MontgomeryDivisorData> divisors, ArrayView<byte> hits)
+	private static void CheckKernel(Index1D index, ulong prime, byte useCycleChecks, ulong cycle, ArrayView<MontgomeryDivisorData> divisors, ArrayView<byte> hits)
 	{
 		MontgomeryDivisorData divisor = divisors[index];
 		ulong modulus = divisor.Modulus;
@@ -326,26 +322,12 @@ public sealed class MersenneNumberDivisorByDivisorGpuTester : IMersenneNumberDiv
 			return;
 		}
 
-        ulong exponent = prime;
 		if (useCycleChecks != 0)
 		{
-            ulong cycle = MersenneDivisorCycles.CalculateCycleLengthGpu(modulus);
+			prime = cycle;
-            if (cycle == 0UL)
-            {
-                hits[index] = 0;
-                return;
-            }
-            ulong remainder = prime % cycle;
-            if (remainder != 0UL)
-            {
-                hits[index] = 0;
-                return;
 		}
 
-            exponent = remainder;
+		hits[index] = prime.Pow2MontgomeryMod(divisor) == 1UL ? (byte)1 : (byte)0;
-        }
-
-        hits[index] = exponent.Pow2MontgomeryMod(divisor) == 1UL ? (byte)1 : (byte)0;
 	}
 
 	public sealed class DivisorScanSession : IMersenneNumberDivisorByDivisorTester.IDivisorScanSession