mlemanczyk/even-perfect-numbers-scanner
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BuildDivisorCandidates moved to MersenneNumberDivisorGpuTester. Micro-optimizations.

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Marek Lemańczyk committed 2025-09-11 21:21:42 +02:00
1 parent 82737b99fd
commit 0535ad2b7b
3 files changed
+216 -224
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EvenPerfectBitScanner/Program.cs
+63 -154
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@@ -26,11 +26,9 @@ internal static class Program
private static int _primeCount;
private static bool _primeFoundAfterInit;
private static bool _useGcdFilter;
private static bool _useResidue;
private static bool _useDivisor;
private static ulong _divisor;
private static MersenneNumberDivisorGpuTester? _divisorTester;
private static (ulong divisor, uint cycle)[]? _divisorCandidates;
private static ulong? _orderWarmupLimitOverride;
private static unsafe delegate*<ulong, ref ulong, ulong> _transformP;
private static long _state;
@@ -367,7 +365,7 @@ internal static class Program
// Apply GPU prime sieve runtime configuration
GpuPrimeWorkLimiter.SetLimit(gpuPrimeThreads);
PerfectNumbers.Core.PrimeTester.GpuBatchSize = Math.Max(1, gpuPrimeBatch);
PrimeTester.GpuBatchSize = Math.Max(1, gpuPrimeBatch);
MersenneDivisorCycles mersenneDivisorCycles = new();
if (!File.Exists(cyclesPath) || continueCyclesGeneration)
@@ -412,7 +410,6 @@ internal static class Program
Console.WriteLine("Divisor cycles are ready");
_useResidue = useResidue;
_useDivisor = useDivisor;
_divisor = divisor;
_transformP = useBitTransform ? &TransformPBit : &TransformPAdd;
@@ -445,17 +442,18 @@ internal static class Program
}
else
{
_divisorTester = new MersenneNumberDivisorGpuTester();
if (divisor == 0UL)
{
_divisorCandidates = BuildDivisorCandidates();
MersenneNumberDivisorGpuTester.BuildDivisorCandidates();
}
_divisorTester = new MersenneNumberDivisorGpuTester();
}
// Load RLE blacklist (optional)
if (!string.IsNullOrEmpty(_rleBlacklistPath))
{
PerfectNumbers.Core.RleBlacklist.Load(_rleBlacklistPath!);
RleBlacklist.Load(_rleBlacklistPath!);
}
ulong remainder = currentP % 6UL;
@@ -552,7 +550,7 @@ internal static class Program
// Limit GPU concurrency only for prime checks (LL/NTT & GPU order scans).
GpuPrimeWorkLimiter.SetLimit(gpuPrimeThreads);
// Configure batch size for GPU primality sieve
PerfectNumbers.Core.PrimeTester.GpuBatchSize = gpuPrimeBatch;
PrimeTester.GpuBatchSize = gpuPrimeBatch;
// Compose a results file name that encodes configuration
ResultsFileName = BuildResultsFileName(
@@ -589,33 +587,33 @@ internal static class Program
}
Console.WriteLine("Starting scan...");
_state = ((long)currentP << 3) | (long)remainder;
Task[] tasks = new Task[threadCount];
_state = ((long)currentP << 3) | (long)remainder;
Task[] tasks = new Task[threadCount];
for (int i = 0; i < threadCount; i++)
{
tasks[i] = Task.Run(() =>
{
ulong[] buffer = new ulong[blockSize];
while (!Volatile.Read(ref _limitReached))
{
int count = ReserveBlock(buffer, blockSize);
if (count == 0)
{
break;
}
for (int i = 0; i < threadCount; i++)
{
tasks[i] = Task.Run(() =>
{
ulong[] buffer = new ulong[blockSize];
while (!Volatile.Read(ref _limitReached))
{
int count = ReserveBlock(buffer, blockSize);
if (count == 0)
{
break;
}
for (int j = 0; j < count && !Volatile.Read(ref _limitReached); j++)
{
ulong p = buffer[j];
if (useFilter && !filter.Contains(p))
{
continue;
}
else if (useFilter)
{
Console.WriteLine($"Testing {p}");
}
for (int j = 0; j < count && !Volatile.Read(ref _limitReached); j++)
{
ulong p = buffer[j];
if (useFilter && !filter.Contains(p))
{
continue;
}
else if (useFilter)
{
Console.WriteLine($"Testing {p}");
}
bool isPerfect = IsEvenPerfectCandidate(p, divisorCyclesSearchLimit, out bool searchedMersenne, out bool detailedCheck);
PrintResult(p, searchedMersenne, detailedCheck, isPerfect);
@@ -736,36 +734,39 @@ internal static class Program
return $"even_perfect_bit_scan_inc-{inc}_thr-{threads}_blk-{block}_mers-{mers}_mersdev-{mersenneDevice}_ntt-{ntt}_red-{red}_primesdev-{primesDevice}_{order}_orderdev-{orderDevice}_{gcd}_{work}_gputh-{gpuPrimeThreads}_llslice-{llSlice}_scanb-{gpuScanBatch}_warm-{warmupLimit}.csv";
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
private static unsafe int ReserveBlock(ulong[] buffer, int blockSize)
{
while (true)
{
long state = Volatile.Read(ref _state);
ulong current = (ulong)state >> 3;
ulong remainder = ((ulong)state) & 7UL;
[MethodImpl(MethodImplOptions.AggressiveInlining)]
private static unsafe int ReserveBlock(ulong[] buffer, int blockSize)
{
Span<ulong> bufferSpan = new(buffer);
ulong p, remainder;
long state, newState, original;
int count;
while (true)
{
state = Volatile.Read(ref _state);
p = (ulong)state >> 3;
remainder = ((ulong)state) & 7UL;
ulong p = current;
int count = 0;
while (count < blockSize && !Volatile.Read(ref _limitReached))
{
buffer[count++] = p;
p = _transformP(p, ref remainder);
}
count = 0;
while (count < blockSize && !Volatile.Read(ref _limitReached))
{
bufferSpan[count++] = p;
p = _transformP(p, ref remainder);
}
if (count == 0)
{
return 0;
}
if (count == 0)
{
return 0;
}
long newState = ((long)p << 3) | (long)remainder;
long original = Interlocked.CompareExchange(ref _state, newState, state);
if (original == state)
{
return count;
}
}
}
newState = ((long)p << 3) | (long)remainder;
original = Interlocked.CompareExchange(ref _state, newState, state);
if (original == state)
{
return count;
}
}
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
private static void PrintResult(ulong currentP, bool searchedMersenne, bool detailedCheck, bool isPerfect)
@@ -913,46 +914,6 @@ internal static class Program
return next + value;
}
private static (ulong divisor, uint cycle)[] BuildDivisorCandidates()
{
uint[] snapshot = MersenneDivisorCycles.Shared.ExportSmallCyclesSnapshot();
Span<(ulong divisor, uint cycle)> list = stackalloc (ulong divisor, uint cycle)[snapshot.Length / 2];// new(snapshot.Length / 2);
uint cycle;
int count = 0, i, snapshotLength = snapshot.Length;
for (i = 3; i < snapshotLength; i += 2)
{
cycle = snapshot[i];
if (cycle == 0U)
{
continue;
}
list[count++] = ((ulong)i, cycle);
}
return list[..count].ToArray();
}
private static bool IsDivisible(ulong exponent, ulong divisor)
{
if (_divisorTester is not null)
{
return _divisorTester.IsDivisible(exponent, divisor);
}
ulong remainder = 1UL;
for (ulong i = 0; i < exponent; i++)
{
remainder <<= 1;
if (remainder >= divisor)
{
remainder -= divisor;
}
}
return remainder == 1UL;
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
internal static bool IsEvenPerfectCandidate(ulong p, int divisorCyclesSearchLimit)
{
@@ -974,7 +935,7 @@ internal static class Program
{
if (!_rleOnlyLast7 || (p % 10UL) == 7UL)
{
if (PerfectNumbers.Core.RleBlacklist.IsLoaded() && PerfectNumbers.Core.RleBlacklist.Matches(p))
if (RleBlacklist.IsLoaded() && RleBlacklist.Matches(p))
{
return false;
}
@@ -1025,59 +986,7 @@ internal static class Program
searchedMersenne = true;
if (_useDivisor)
{
if (_divisor != 0UL)
{
if (IsDivisible(p, _divisor))
{
detailedCheck = true;
return false;
}
detailedCheck = false;
return true;
}
var candidates = _divisorCandidates!;
int len = candidates.Length;
for (int i = 0; i < len; i++)
{
var (d, cycle) = candidates[i];
if (p % cycle != 0UL)
{
continue;
}
if (IsDivisible(p, d))
{
detailedCheck = true;
return false;
}
}
for (int k = 1; k <= divisorCyclesSearchLimit; k++)
{
ulong kMul2 = 2UL * (ulong)k;
if (p > ulong.MaxValue / kMul2)
{
break;
}
ulong d = kMul2 * p + 1UL;
ulong cycle = MersenneDivisorCycles.Shared.GetCycle(d);
if (p % cycle != 0UL)
{
continue;
}
if (IsDivisible(p, d))
{
detailedCheck = true;
return false;
}
}
detailedCheck = false;
return true;
return _divisorTester!.IsPrime(p, _divisor, divisorCyclesSearchLimit, out detailedCheck);
}
detailedCheck = MersenneTesters.Value!.IsMersennePrime(p);