From 14f76b353d681eb92fa0cd113c2e9c666aaea951 Mon Sep 17 00:00:00 2001 From: David Phillips Date: Mon, 19 Sep 2016 13:33:11 +1200 Subject: Fix upside-down division, use more accurate time stamps --- fractal-gen.c | 26 +++++++++++++++++++------- 1 file changed, 19 insertions(+), 7 deletions(-) diff --git a/fractal-gen.c b/fractal-gen.c index fbe7958..fce146f 100644 --- a/fractal-gen.c +++ b/fractal-gen.c @@ -56,6 +56,15 @@ defaultsd(double *who, double def) *who = def; } +double +timespec_diff(struct timespec start, struct timespec end) { + long weight = 1000000000; + time_t s = (end.tv_sec - start.tv_sec); + long ns = (end.tv_nsec - start.tv_nsec) % weight; + + return s + ((double)ns)/weight; +} + void *generate(void *section) { data_section *s = (data_section*)section; @@ -186,17 +195,21 @@ main(int argc, char **argv) clock_gettime(CLOCK_REALTIME, &time_end); - long time_wall = time_end.tv_sec - time_start.tv_sec; - long time_ch = 0; + fprintf(stderr, "\nDone\n"); + + double time_wall = timespec_diff(time_start, time_end); + double time_ch = 0; + for (i = 0; i < cores; i++) { - time_ch += sections[i].time_end.tv_sec - sections[i].time_start.tv_sec; + data_section *s = &(sections[i]); + time_ch += (timespec_diff(s->time_start, s->time_end)) / cores; } fprintf(stderr, - "Wall-clock time: %ld\n" - "Worker time: %ld\n" + "Wall-clock time: %.2f seconds\n" + "Average worker time: %.2f seconds\n" "Multi-core efficiency: %.2f%%\n" - , time_wall, time_ch, 100*((double)(time_wall*cores))/time_ch); + , time_wall, time_ch, 100*(time_ch)/time_wall); /* Output PGM Header */ printf("P5\n%d\n%d\n255\n",size,size/clust_total); @@ -210,7 +223,6 @@ main(int argc, char **argv) putchar(s->data[y*(s->width) + x/cores]); } } - fprintf(stderr, "\nDone\n"); /* Free the memory we allocated for point data */ for (i = 0; i < cores; i++) -- cgit v1.1