commit 2a9d3bf13585c5378e5b1bddb77106ee86719d29
parent 9a60392849d6560b5a87ff9473ece37386dcd9d2
Author: NunoSempere <nuno.sempere@protonmail.com>
Date: Sat, 18 Nov 2023 19:43:10 +0000
factorize paralellization in C code out
- Conceptually clearer
- Allows for composing multiple mixtures together
- Considering incorporating it into squiggle.c
Diffstat:
10 files changed, 260 insertions(+), 309 deletions(-)
diff --git a/C/alt/03-factor-out-parallelization/samples.c b/C/alt/03-factor-out-parallelization/samples.c
@@ -1,309 +0,0 @@
-#include <math.h>
-#include <omp.h>
-#include <stdint.h>
-#include <stdio.h>
-#include <stdlib.h>
-
-const float PI = 3.14159265358979323846;
-
-#define N 1000000
-
-//Array helpers
-
-void array_print(float* array, int length)
-{
- for (int i = 0; i < length; i++) {
- printf("item[%d] = %f\n", i, array[i]);
- }
- printf("\n");
-}
-
-float array_sum(float* array, int length)
-{
- float output = 0.0;
- for (int i = 0; i < length; i++) {
- output += array[i];
- }
- return output;
-}
-
-void array_cumsum(float* array_to_sum, float* array_cumsummed, int length)
-{
- array_cumsummed[0] = array_to_sum[0];
- for (int i = 1; i < length; i++) {
- array_cumsummed[i] = array_cumsummed[i - 1] + array_to_sum[i];
- }
-}
-
-// Split array helpers
-int split_array_get_length(int index, int total_length, int n_threads)
-{
- return (total_length % n_threads > index ? total_length / n_threads + 1 : total_length / n_threads);
-}
-
-void split_array_allocate(float** meta_array, int length, int divide_into)
-{
- int split_array_length;
-
- for (int i = 0; i < divide_into; i++) {
- split_array_length = split_array_get_length(i, length, divide_into);
- meta_array[i] = malloc(split_array_length * sizeof(float));
- }
-}
-
-void split_array_free(float** meta_array, int divided_into)
-{
- for (int i = 0; i < divided_into; i++) {
- free(meta_array[i]);
- }
- free(meta_array);
-}
-
-float split_array_sum(float** meta_array, int length, int divided_into)
-{
- int i;
- float output = 0;
-
-#pragma omp parallel for reduction(+ \
- : output)
- for (int i = 0; i < divided_into; i++) {
- float own_partial_sum = 0;
- int split_array_length = split_array_get_length(i, length, divided_into);
- for (int j = 0; j < split_array_length; j++) {
- own_partial_sum += meta_array[i][j];
- }
- output += own_partial_sum;
- }
- return output;
-}
-
-// Pseudo Random number generator
-
-uint32_t xorshift32(uint32_t* seed)
-{
- // Algorithm "xor" from p. 4 of Marsaglia, "Xorshift RNGs"
- // See <https://stackoverflow.com/questions/53886131/how-does-xorshift32-works>
- // https://en.wikipedia.org/wiki/Xorshift
- // Also some drama: <https://www.pcg-random.org/posts/on-vignas-pcg-critique.html>, <https://prng.di.unimi.it/>
-
- uint32_t x = *seed;
- x ^= x << 13;
- x ^= x >> 17;
- x ^= x << 5;
- return *seed = x;
-}
-
-// Distribution & sampling functions
-
-float rand_0_to_1(uint32_t* seed)
-{
- return ((float)xorshift32(seed)) / ((float)UINT32_MAX);
- /*
- uint32_t x = *seed;
- x ^= x << 13;
- x ^= x >> 17;
- x ^= x << 5;
- return ((float)(*seed = x))/((float) UINT32_MAX);
- */
- // previously:
- // ((float)rand_r(seed) / (float)RAND_MAX)
- // and before that: rand, but it wasn't thread-safe.
- // See: <https://stackoverflow.com/questions/43151361/how-to-create-thread-safe-random-number-generator-in-c-using-rand-r> for why to use rand_r:
- // rand() is not thread-safe, as it relies on (shared) hidden seed.
-}
-
-float rand_float(float max, uint32_t* seed)
-{
- return rand_0_to_1(seed) * max;
-}
-
-float ur_normal(uint32_t* seed)
-{
- float u1 = rand_0_to_1(seed);
- float u2 = rand_0_to_1(seed);
- float z = sqrtf(-2.0 * log(u1)) * sin(2 * PI * u2);
- return z;
-}
-
-float random_uniform(float from, float to, uint32_t* seed)
-{
- return rand_0_to_1(seed) * (to - from) + from;
-}
-
-float random_normal(float mean, float sigma, uint32_t* seed)
-{
- return (mean + sigma * ur_normal(seed));
-}
-
-float random_lognormal(float logmean, float logsigma, uint32_t* seed)
-{
- return expf(random_normal(logmean, logsigma, seed));
-}
-
-float random_to(float low, float high, uint32_t* seed)
-{
- const float NORMAL95CONFIDENCE = 1.6448536269514722;
- float loglow = logf(low);
- float loghigh = logf(high);
- float logmean = (loglow + loghigh) / 2;
- float logsigma = (loghigh - loglow) / (2.0 * NORMAL95CONFIDENCE);
- return random_lognormal(logmean, logsigma, seed);
-}
-
-// Mixture function
-
-float mixture_one_thread(float (*samplers[])(uint32_t*), float* weights, int n_dists, uint32_t* seed)
-{
-
- // You can see a slightly simpler version of this function in the git history
- // or in alt/C-02-better-algorithm-one-thread/
- float sum_weights = array_sum(weights, n_dists);
- float* cumsummed_normalized_weights = malloc(n_dists * sizeof(float));
- cumsummed_normalized_weights[0] = weights[0] / sum_weights;
- for (int i = 1; i < n_dists; i++) {
- cumsummed_normalized_weights[i] = cumsummed_normalized_weights[i - 1] + weights[i] / sum_weights;
- }
-
- //create var holders
- float p1, result;
- int sample_index, i, own_length;
- p1 = random_uniform(0, 1);
- for (int i = 0; i < n_dists; i++) {
- if (p1 < cummulative_weights[i]) {
- result = samplers[i]();
- break;
- }
- }
- free(normalized_weights);
- free(cummulative_weights);
- return result;
-}
-
-// mixture paralellized
-void mixture_paralell(float (*samplers[])(uint32_t*), float* weights, int n_dists, float** results, int n_threads)
-{
- // You can see a simpler version of this function in the git history
- // or in alt/C-02-better-algorithm-one-thread/
- float sum_weights = array_sum(weights, n_dists);
- float* cumsummed_normalized_weights = malloc(n_dists * sizeof(float));
- cumsummed_normalized_weights[0] = weights[0] / sum_weights;
- for (int i = 1; i < n_dists; i++) {
- cumsummed_normalized_weights[i] = cumsummed_normalized_weights[i - 1] + weights[i] / sum_weights;
- }
-
- //create var holders
- float p1;
- int sample_index, i, split_array_length;
-
- // uint32_t* seeds[n_threads];
- uint32_t** seeds = malloc(n_threads * sizeof(uint32_t*));
- for (uint32_t i = 0; i < n_threads; i++) {
- seeds[i] = malloc(sizeof(uint32_t));
- *seeds[i] = i + 1; // xorshift can't start with 0
- }
-
-#pragma omp parallel private(i, p1, sample_index, split_array_length)
- {
-#pragma omp for
- for (i = 0; i < n_threads; i++) {
- split_array_length = split_array_get_length(i, N, n_threads);
- for (int j = 0; j < split_array_length; j++) {
- p1 = random_uniform(0, 1, seeds[i]);
- for (int k = 0; k < n_dists; k++) {
- if (p1 < cumsummed_normalized_weights[k]) {
- results[i][j] = samplers[k](seeds[i]);
- break;
- }
- }
- }
- }
- }
- // free(normalized_weights);
- // free(cummulative_weights);
- free(cumsummed_normalized_weights);
- for (uint32_t i = 0; i < n_threads; i++) {
- free(seeds[i]);
- }
- free(seeds);
-}
-
-// Parallization function
-void paralellize(float *sampler(uint32_t* seed), float** results, int n_threads){
-
- int sample_index, i, split_array_length;
- uint32_t** seeds = malloc(n_threads * sizeof(uint32_t*));
- for (uint32_t i = 0; i < n_threads; i++) {
- seeds[i] = malloc(sizeof(uint32_t));
- *seeds[i] = i + 1; // xorshift can't start with 0
- }
-
- #pragma omp parallel private(i, p1, sample_index, split_array_length)
- {
- #pragma omp for
- for (i = 0; i < n_threads; i++) {
- split_array_length = split_array_get_length(i, N, n_threads);
- for (int j = 0; j < split_array_length; j++) {
- results[i][j] = sampler(seeds[i]);
- break;
- }
- }
- }
- free(cumsummed_normalized_weights);
- for (uint32_t i = 0; i < n_threads; i++) {
- free(seeds[i]);
- }
- free(seeds);
-}
-
-// Functions used for the BOTEC.
-// Their type has to be the same, as we will be passing them around.
-
-float sample_0(uint32_t* seed)
-{
- return 0;
-}
-
-float sample_1(uint32_t* seed)
-{
- return 1;
-}
-
-float sample_few(uint32_t* seed)
-{
- return random_to(1, 3, seed);
-}
-
-float sample_many(uint32_t* seed)
-{
- return random_to(2, 10, seed);
-}
-
-int main()
-{
-
- // Toy example
- // Declare variables in play
- float p_a, p_b, p_c;
- int n_threads = omp_get_max_threads();
- // printf("Max threads: %d\n", n_threads);
- // omp_set_num_threads(n_threads);
- float** dist_mixture = malloc(n_threads * sizeof(float*));
- split_array_allocate(dist_mixture, N, n_threads);
-
- // Initialize variables
- p_a = 0.8;
- p_b = 0.5;
- p_c = p_a * p_b;
-
- // Generate mixture
- int n_dists = 4;
- float weights[] = { 1 - p_c, p_c / 2, p_c / 4, p_c / 4 };
- float (*samplers[])(uint32_t*) = { sample_0, sample_1, sample_few, sample_many };
-
- mixture(samplers, weights, n_dists, dist_mixture, n_threads);
- printf("Sum(dist_mixture, N)/N = %f\n", split_array_sum(dist_mixture, N, n_threads) / N);
- // array_print(dist_mixture[0], N);
- split_array_free(dist_mixture, n_threads);
-
- return 0;
-}
diff --git a/C/alt/xorshift-scratchpad/makefile b/C/alt/03-xorshift-scratchpad/makefile
diff --git a/C/alt/xorshift-scratchpad/notes.md b/C/alt/03-xorshift-scratchpad/notes.md
diff --git a/C/alt/xorshift-scratchpad/out/xorshift-pointer b/C/alt/03-xorshift-scratchpad/out/xorshift-pointer
Binary files differ.
diff --git a/C/alt/xorshift-scratchpad/out/xorshift-struct b/C/alt/03-xorshift-scratchpad/out/xorshift-struct
Binary files differ.
diff --git a/C/alt/xorshift-scratchpad/xorshift-pointer.c b/C/alt/03-xorshift-scratchpad/xorshift-pointer.c
diff --git a/C/alt/xorshift-scratchpad/xorshift-struct.c b/C/alt/03-xorshift-scratchpad/xorshift-struct.c
diff --git a/C/alt/03-factor-out-parallelization/makefile b/C/alt/04-factor-out-paralellization/makefile
diff --git a/C/alt/04-factor-out-paralellization/out/samples b/C/alt/04-factor-out-paralellization/out/samples
Binary files differ.
diff --git a/C/alt/04-factor-out-paralellization/samples.c b/C/alt/04-factor-out-paralellization/samples.c
@@ -0,0 +1,260 @@
+#include <math.h>
+#include <omp.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+const float PI = 3.14159265358979323846;
+
+#define N 1000000
+
+//Array helpers
+
+void array_print(float* array, int length)
+{
+ for (int i = 0; i < length; i++) {
+ printf("item[%d] = %f\n", i, array[i]);
+ }
+ printf("\n");
+}
+
+float array_sum(float* array, int length)
+{
+ float output = 0.0;
+ for (int i = 0; i < length; i++) {
+ output += array[i];
+ }
+ return output;
+}
+
+void array_cumsum(float* array_to_sum, float* array_cumsummed, int length)
+{
+ array_cumsummed[0] = array_to_sum[0];
+ for (int i = 1; i < length; i++) {
+ array_cumsummed[i] = array_cumsummed[i - 1] + array_to_sum[i];
+ }
+}
+
+// Split array helpers
+int split_array_get_length(int index, int total_length, int n_threads)
+{
+ return (total_length % n_threads > index ? total_length / n_threads + 1 : total_length / n_threads);
+}
+
+void split_array_allocate(float** meta_array, int length, int divide_into)
+{
+ int split_array_length;
+
+ for (int i = 0; i < divide_into; i++) {
+ split_array_length = split_array_get_length(i, length, divide_into);
+ meta_array[i] = malloc(split_array_length * sizeof(float));
+ }
+}
+
+void split_array_free(float** meta_array, int divided_into)
+{
+ for (int i = 0; i < divided_into; i++) {
+ free(meta_array[i]);
+ }
+ free(meta_array);
+}
+
+float split_array_sum(float** meta_array, int length, int divided_into)
+{
+ int i;
+ float output = 0;
+
+#pragma omp parallel for reduction(+ \
+ : output)
+ for (int i = 0; i < divided_into; i++) {
+ float own_partial_sum = 0;
+ int split_array_length = split_array_get_length(i, length, divided_into);
+ for (int j = 0; j < split_array_length; j++) {
+ own_partial_sum += meta_array[i][j];
+ }
+ output += own_partial_sum;
+ }
+ return output;
+}
+
+// Pseudo Random number generator
+
+uint32_t xorshift32(uint32_t* seed)
+{
+ // Algorithm "xor" from p. 4 of Marsaglia, "Xorshift RNGs"
+ // See <https://stackoverflow.com/questions/53886131/how-does-xorshift32-works>
+ // https://en.wikipedia.org/wiki/Xorshift
+ // Also some drama: <https://www.pcg-random.org/posts/on-vignas-pcg-critique.html>, <https://prng.di.unimi.it/>
+
+ uint32_t x = *seed;
+ x ^= x << 13;
+ x ^= x >> 17;
+ x ^= x << 5;
+ return *seed = x;
+}
+
+// Distribution & sampling functions
+
+float rand_0_to_1(uint32_t* seed)
+{
+ return ((float)xorshift32(seed)) / ((float)UINT32_MAX);
+ /*
+ uint32_t x = *seed;
+ x ^= x << 13;
+ x ^= x >> 17;
+ x ^= x << 5;
+ return ((float)(*seed = x))/((float) UINT32_MAX);
+ */
+ // previously:
+ // ((float)rand_r(seed) / (float)RAND_MAX)
+ // and before that: rand, but it wasn't thread-safe.
+ // See: <https://stackoverflow.com/questions/43151361/how-to-create-thread-safe-random-number-generator-in-c-using-rand-r> for why to use rand_r:
+ // rand() is not thread-safe, as it relies on (shared) hidden seed.
+}
+
+float rand_float(float max, uint32_t* seed)
+{
+ return rand_0_to_1(seed) * max;
+}
+
+float ur_normal(uint32_t* seed)
+{
+ float u1 = rand_0_to_1(seed);
+ float u2 = rand_0_to_1(seed);
+ float z = sqrtf(-2.0 * log(u1)) * sin(2 * PI * u2);
+ return z;
+}
+
+float random_uniform(float from, float to, uint32_t* seed)
+{
+ return rand_0_to_1(seed) * (to - from) + from;
+}
+
+float random_normal(float mean, float sigma, uint32_t* seed)
+{
+ return (mean + sigma * ur_normal(seed));
+}
+
+float random_lognormal(float logmean, float logsigma, uint32_t* seed)
+{
+ return expf(random_normal(logmean, logsigma, seed));
+}
+
+float random_to(float low, float high, uint32_t* seed)
+{
+ const float NORMAL95CONFIDENCE = 1.6448536269514722;
+ float loglow = logf(low);
+ float loghigh = logf(high);
+ float logmean = (loglow + loghigh) / 2;
+ float logsigma = (loghigh - loglow) / (2.0 * NORMAL95CONFIDENCE);
+ return random_lognormal(logmean, logsigma, seed);
+}
+
+// Mixture function
+
+float mixture(float (*samplers[])(uint32_t*), float* weights, int n_dists, uint32_t* seed)
+{
+
+ // You can see a slightly simpler version of this function in the git history
+ // or in alt/C-02-better-algorithm-one-thread/
+ float sum_weights = array_sum(weights, n_dists);
+ float* cumsummed_normalized_weights = malloc(n_dists * sizeof(float));
+ cumsummed_normalized_weights[0] = weights[0] / sum_weights;
+ for (int i = 1; i < n_dists; i++) {
+ cumsummed_normalized_weights[i] = cumsummed_normalized_weights[i - 1] + weights[i] / sum_weights;
+ }
+
+ //create var holders
+ float p1, result;
+ int sample_index, i, own_length;
+ p1 = random_uniform(0, 1, seed);
+ for (int i = 0; i < n_dists; i++) {
+ if (p1 < cumsummed_normalized_weights[i]) {
+ result = samplers[i](seed);
+ break;
+ }
+ }
+ free(cumsummed_normalized_weights);
+ return result;
+}
+
+// Parallization function
+void paralellize(float (*sampler)(uint32_t* seed), float** results, int n_threads){
+
+ int sample_index, i, split_array_length;
+ uint32_t** seeds = malloc(n_threads * sizeof(uint32_t*));
+ for (uint32_t i = 0; i < n_threads; i++) {
+ seeds[i] = malloc(sizeof(uint32_t));
+ *seeds[i] = i + 1; // xorshift can't start with 0
+ }
+
+ #pragma omp parallel private(i, sample_index, split_array_length)
+ {
+ #pragma omp for
+ for (i = 0; i < n_threads; i++) {
+ split_array_length = split_array_get_length(i, N, n_threads);
+ for (int j = 0; j < split_array_length; j++) {
+ results[i][j] = sampler(seeds[i]);
+ }
+ }
+ }
+
+ for (uint32_t i = 0; i < n_threads; i++) {
+ free(seeds[i]);
+ }
+ free(seeds);
+}
+
+// Functions used for the BOTEC.
+// Their type has to be the same, as we will be passing them around.
+
+float sample_0(uint32_t* seed)
+{
+ return 0;
+}
+
+float sample_1(uint32_t* seed)
+{
+ return 1;
+}
+
+float sample_few(uint32_t* seed)
+{
+ return random_to(1, 3, seed);
+}
+
+float sample_many(uint32_t* seed)
+{
+ return random_to(2, 10, seed);
+}
+
+float sample_mixture(uint32_t* seed){
+ float p_a, p_b, p_c;
+
+ // Initialize variables
+ p_a = 0.8;
+ p_b = 0.5;
+ p_c = p_a * p_b;
+
+ // Generate mixture
+ int n_dists = 4;
+ float weights[] = { 1 - p_c, p_c / 2, p_c / 4, p_c / 4 };
+ float (*samplers[])(uint32_t*) = { sample_0, sample_1, sample_few, sample_many };
+
+ return mixture(samplers, weights, n_dists, seed);
+}
+
+int main()
+{
+ int n_threads = omp_get_max_threads();
+ // printf("Max threads: %d\n", n_threads);
+ // omp_set_num_threads(n_threads);
+ float** split_array_results = malloc(n_threads * sizeof(float*));
+ split_array_allocate(split_array_results, N, n_threads);
+
+ paralellize(sample_mixture, split_array_results, n_threads);
+ printf("Sum(split_array_results, N)/N = %f\n", split_array_sum(split_array_results, N, n_threads) / N);
+
+ split_array_free(split_array_results, n_threads);
+ return 0;
+}
