Files
Jungfraujoch/image_analysis/bragg_integration/BraggIntegrationEngineGPU.h
T
jungfrauandClaude Opus 5 16639e9de2 Add up the profile accumulators in an order the schedule cannot change
Every accumulator in this file that could be an integer already is one, and the spot finder's
reduce_rings_shared says why: a preprocessed pixel is an exact int32, integer addition is
associative, and a threshold that moves in its last bits between runs flips every pixel sitting on
it. Four accumulators here were still floats, and they reach the intensity rather than a diagnostic.

* The radial background curve. s_radv and rad_sum sum int32 pixel values, so int64 is not an
  approximation of the old sum, it IS the old sum - and the curve is subtracted from every
  reflection's background.
* The learned profile grid and its second moments, which are sums of (px - bkg) / I over every
  strong reflection of the frame. There is no exact integer form, so these are fixed point at 2^20:
  a quantum of 1e-6 of one I-normalised pixel, far below the Poisson noise of the pixel it came
  from, and some five orders of headroom inside a signed 64-bit accumulator.
* The normalisation total in build_profiles, which divides every cell of the profile - 128 lanes on
  one address, in arrival order. Now summed as integers, exactly, from the grid it normalises.
* The fit's own reductions, s_num and s_den among them, which ARE the fitted intensity. These stay
  float, so fixed point would be a real precision trade over an unbounded range; instead each warp
  leaves its total in a slot of its own and every thread adds the slots up by warp index.
  WARP_ATOMIC_ADD is order-independent for the integer accumulators it was written for and not for
  these, which is what block_sum is for.

With the prediction ordering of the previous commit, a run is now reproducible: the same command on
the same images writes byte-identical .hkl and .mtz, at -N 1 and at -N 48, on a 16 Mpx rotation set
and on a large-cell one. Before, all four differed.

The battery is unchanged where it was ever stable: space group identical on all 24 crystals,
reflection count on 20, R_meas on 22. The two that move are the two the battery has always seen
move between runs of an unchanged binary - which is the point, since they stop moving now. Total
8m02s against 7m55s, inside the noise of per-crystal times quantised to a second.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011n8riB6X59oRjkrSHzNPAU
2026-08-23 10:56:02 -04:00

74 lines
4.0 KiB
C++

// SPDX-FileCopyrightText: 2026 Filip Leonarski, Paul Scherrer Institute <filip.leonarski@psi.ch>
// SPDX-License-Identifier: GPL-3.0-only
#pragma once
#include <cstdint>
#include <memory>
#include <vector>
#include "BraggIntegrationEngine.h"
#include "../indexing/CUDAMemHelpers.h"
// CUDA engine: reproduces BraggIntegrationEngineCPU up to floating-point precision. Each stage is a
// kernel with one CUDA block per reflection cooperating over the small window via shared-memory
// reductions (the natural mapping for thousands of independent, tiny per-spot integrations).
//
// Pipeline (profile modes): reset -> mark_mask -> boxsum -> learn_profile -> build_profiles -> fit
// (the resolution shell is computed inline, so there is no separate shell pass). BoxSum mode stops
// after boxsum (that pass is the BraggIntegrate2D box integrator and the seed of the profile fit).
// The preprocessed image already lives on the device (ImagePreprocessorBufferGPU::getGPUBuffer());
// only the per-frame predicted centres are uploaded.
class BraggIntegrationEngineGPU : public BraggIntegrationEngine {
std::shared_ptr<CudaStream> stream;
int threads;
size_t fit_shared_bytes;
int rad_w = 0; // radial-background window of boxsum, in bins of one pixel
size_t boxsum_shared_bytes = 0;
size_t capacity = 0; // per-reflection device/host arrays hold at least this many reflections
// --- per-reflection device arrays (grown by EnsureCapacity) ---
CudaDevicePtr<float> d_px_x, d_px_y, d_d;
CudaDevicePtr<int> d_cx, d_cy;
CudaDevicePtr<float> d_I, d_sigma, d_bkg, d_bkg_var, d_var_bkg, d_obs_x, d_obs_y;
CudaDevicePtr<float> d_isum; // box-sum raw sum, for the radial correction
CudaDevicePtr<int> d_ninner, d_rbin, d_kbin;
CudaDevicePtr<uint8_t> d_ok, d_strong, d_has_obs;
// --- radial background curvature correction (see BraggIntegrationEngine) ---
int n_rad = 0; // radial bins, 0 when the correction is off
CudaDevicePtr<unsigned long long> d_rad_sum; // integer pixel sums, see boxsum
CudaDevicePtr<float> d_k_diff;
CudaDevicePtr<int> d_rad_cnt;
// --- fixed-size device arrays ---
// The learning/fit math is single precision: FP64 is heavily throttled on consumer GPUs and the
// extraction is Poisson-noise limited, so float reproduces the double CPU path to ~1e-4.
CudaDevicePtr<uint8_t> d_mask; // per-pixel inner-stencil reflection mask
// Per-pixel (distance, reflection) key naming the nearest predicted centre; allocated only when
// an overlap treatment is on, so the default path costs no extra device memory.
CudaDevicePtr<uint32_t> d_owner;
// Fixed-point (see PROFILE_FIXED): a float atomicAdd here made the profile depend on the order
// the blocks arrived in, and with it every intensity fitted through it.
CudaDevicePtr<unsigned long long> d_shell_grid, d_global_grid; // learned profile accumulators (N_SHELL*GG, GG)
CudaDevicePtr<float> d_shell_P, d_global_P; // normalised profiles (empirical mode)
CudaDevicePtr<unsigned long long> d_mom; // learned 2nd moments, 3 per shell + global
CudaDevicePtr<float> d_sigma2_r, d_sigma2_t; // radial/tangential widths, N_SHELL + global
CudaDevicePtr<int> d_shell_n, d_global_n;
CudaDevicePtr<unsigned long long> d_invd2; // [min,max] inv-d^2 as monotonic bit patterns
// --- host staging (copied back once per frame) ---
std::vector<float> h_px_x, h_px_y, h_d;
std::vector<float> h_I, h_sigma, h_bkg, h_var_bkg, h_obs_x, h_obs_y;
std::vector<uint8_t> h_ok, h_has_obs;
void EnsureCapacity(size_t n);
public:
BraggIntegrationEngineGPU(const DiffractionExperiment &experiment, std::shared_ptr<CudaStream> stream);
std::vector<Reflection> Run(const ImagePreprocessorBuffer &image,
const std::vector<Reflection> &predicted, size_t npredicted,
int64_t image_number) override;
};