mlemanczyk/even-perfect-numbers-scanner
1
0 Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Add TODOs for divisor metadata caching

Browse Source
This commit is contained in:
Marek Lemańczyk committed 2025-10-01 22:52:21 +02:00
1 parent 513fc7acb0
commit 36d316d19c
53 files changed
+929 -393
Download Patch File Download Diff File Expand all files Collapse all files

No files matched your search

PerfectNumbers.Core/Gpu/GpuKernelPool.cs
+15 -1
View File
@@ -199,6 +199,8 @@ public ref struct GpuKernelLease(IDisposable limiter, GpuContextLease gpu, Kerne
ArrayView1D<ulong, Stride1D.Dense> smallCycles)
{
ulong idx = (ulong)index.X;
// TODO: Replace these `%` computations with the precomputed Mod3/Mod5 tables so GPU kernels reuse cached residues
// instead of performing modulo operations that the benchmarks showed slower on wide sweeps.
ulong idxMod3 = idx % 3UL;
ulong idxMod5 = idx % 5UL;
// residue automaton
@@ -216,7 +218,9 @@ public ref struct GpuKernelLease(IDisposable limiter, GpuContextLease gpu, Kerne
}
else
{
ulong step3 = ((exponent % 3UL) << 1) % 3UL;
// TODO: Swap these `%` filters to the shared Mod helpers so the residue automaton matches the benchmarked
// bitmask-based implementation for GPU workloads.
ulong step3 = ((exponent % 3UL) << 1) % 3UL;
ulong r3 = q0m3 + (step3 * idxMod3); r3 -= (r3 >= 3UL) ? 3UL : 0UL;
if (r3 == 0UL)
{
@@ -264,6 +268,8 @@ public ref struct GpuKernelLease(IDisposable limiter, GpuContextLease gpu, Kerne
}
ulong phi64 = phi.Low;
// TODO: Replace these Pow2Mod calls with the ProcessEightBitWindows helper when the shared windowed
// scalar implementation lands; benchmarks showed the windowed kernel trimming per-divisor runtime by ~2.4×.
if (GpuUInt128.Pow2Mod(phi64, q) != GpuUInt128.One)
{
orders[index] = 0UL;
@@ -299,6 +305,8 @@ public ref struct GpuKernelLease(IDisposable limiter, GpuContextLease gpu, Kerne
}
ulong phi64 = phi.Low;
// TODO: Once the ProcessEightBitWindows helper is available, switch this order kernel to that faster
// Pow2Mod variant so cycle checks inherit the same gains observed in GpuPow2ModBenchmarks.
GpuUInt128 pow = GpuUInt128.Pow2Mod(phi64, q);
if (pow != GpuUInt128.One)
{
@@ -409,6 +417,8 @@ public ref struct GpuKernelLease(IDisposable limiter, GpuContextLease gpu, Kerne
return;
}
}
// TODO: Swap Pow2Minus1Mod for the eight-bit window helper once the scalar version switches;
// benchmarks show the windowed variant cuts large-divisor scans from ~51 µs to ~21 µs.
if (GpuUInt128.Pow2Minus1Mod(exponent, q) != GpuUInt128.Zero)
{
orders[index] = 0UL;
@@ -563,6 +573,8 @@ public ref struct GpuKernelLease(IDisposable limiter, GpuContextLease gpu, Kerne
}
ulong phi64 = phi.Low;
// TODO: Upgrade this pow2mod order kernel to the ProcessEightBitWindows helper once available so GPU residue
// scans avoid the single-bit ladder that benchmarks found to be 2.3× slower on large exponents.
if (GpuUInt128.Pow2Mod(phi64, q) != GpuUInt128.One)
{
return;
@@ -639,6 +651,8 @@ public ref struct GpuKernelLease(IDisposable limiter, GpuContextLease gpu, Kerne
return;
}
}
// TODO: Replace this Pow2Mod check with the ProcessEightBitWindows helper once Pow2Minus1Mod adopts it;
// residue order scans will then benefit from the same 2× speedup the benchmarked windowed kernel delivered.
if (GpuUInt128.Pow2Mod(exponent, q) != GpuUInt128.One)
{
return;