performance measurements
Each table row shows performance measurements for this C gcc program with a particular command-line input value N.
| N | CPU secs | Elapsed secs | Memory KB | Code B | ≈ CPU Load |
|---|---|---|---|---|---|
| 500 | 0.08 | 0.09 | ? | 1139 | 0% 0% 0% 100% |
| 3,000 | 2.94 | 2.94 | 644 | 1139 | 0% 0% 0% 100% |
| 5,500 | 9.87 | 9.88 | 644 | 1139 | 0% 0% 0% 100% |
Read the ↓ make, command line, and program output logs to see how this program was run.
Read spectral-norm benchmark to see what this program should do.
notes
gcc (Ubuntu/Linaro 4.7.3-1ubuntu1) 4.7.3
spectral-norm C gcc #4 program source code
/* The Computer Language Benchmarks Game * http://benchmarksgame.alioth.debian.org/ * * Original C contributed by Sebastien Loisel * Conversion to C++ by Jon Harrop * OpenMP parallelize by The Anh Tran * Add SSE by The Anh Tran * Reconversion into C by Dan Farina */ #define _GNU_SOURCE #include <omp.h> #include <math.h> #include <sched.h> #include <stdio.h> #include <stdlib.h> #define false 0 #define true 1 /* define SIMD data type. 2 doubles encapsulated in one XMM register */ typedef double v2dt __attribute__((vector_size(16))); static const v2dt v1 = {1.0, 1.0}; /* parameter for evaluate functions */ struct Param { double* u; /* source vector */ double* tmp; /* temporary */ double* v; /* destination vector */ int N; /* source/destination vector length */ int N2; /* = N/2 */ int r_begin; /* working range of each thread */ int r_end; }; /* Return: 1.0 / (i + j) * (i + j +1) / 2 + i + 1; */ static double eval_A(int i, int j) { /* * 1.0 / (i + j) * (i + j +1) / 2 + i + 1; * n * (n+1) is even number. Therefore, just (>> 1) for (/2) */ int d = (((i+j) * (i+j+1)) >> 1) + i+1; return 1.0 / d; } /* * Return type: 2 doubles in xmm register [double1, double2] * double1 = 1.0 / (i + j) * (i + j +1) / 2 + i + 1; * double2 = 1.0 / (i+1 + j) * (i+1 + j +1) / 2 + i+1 + 1; */ static v2dt eval_A_i(int i, int j) { int d1 = (((i+j) * (i+j+1)) >> 1) + i+1; int d2 = (((i+1 +j) * (i+1 +j+1)) >> 1) + (i+1) +1; v2dt r = {d1, d2}; return v1 / r; } /* * Return type: 2 doubles in xmm register [double1, double2] * double1 = 1.0 / (i + j) * (i + j +1) / 2 + i + 1; * double2 = 1.0 / (i + j+1) * (i + j+1 +1) / 2 + i + 1; */ static v2dt eval_A_j(int i, int j) { int d1 = (((i+j) * (i+j+1)) >> 1) + i+1; int d2 = (((i+ j+1) * (i+ j+1 +1)) >> 1) + i+1; v2dt r = {d1, d2}; return v1 / r; } /* This function is called by many threads */ static void eval_A_times_u(struct Param *p) { /* alias of source vector */ const v2dt *pU = (void *) p->u; int i; int ie; for (i = p->r_begin, ie = p->r_end; i < ie; i++) { v2dt sum = {0, 0}; /* xmm = 2 doubles. This loop run from [0 .. N/2) */ int j; for (j = 0; j < p->N2; j++) sum += pU[j] * eval_A_j(i, j*2); /* write result */ { double *mem = (void *) ∑ p->tmp[i] = mem[0] + mem[1]; } /* If source vector is odd size. This should be called <= 1 time */ for (j = j*2; __builtin_expect(j < p->N, false); j++) p->tmp[i] += eval_A(i, j) * p->u[j]; } } static void eval_At_times_u(struct Param *p) { const v2dt *pT = (void *) p->tmp; int i; int ie; for (i = p->r_begin, ie = p->r_end; i < ie; i++) { v2dt sum = {0, 0}; int j; for (j = 0; j < p->N2; j++) sum += pT[j] * eval_A_i(j*2, i); { double *mem = (void *) ∑ p->v[i] = mem[0] + mem[1]; } /* odd size array */ for (j = j*2; __builtin_expect(j < p->N, false); j++) p->v[i] += eval_A(j, i) * p->tmp[j]; } } /* * Called by N threads. * * Each thread modifies its portion in destination vector -> barrier needed to * sync access */ static void eval_AtA_times_u(struct Param *p) { eval_A_times_u(p); #pragma omp barrier eval_At_times_u(p); #pragma omp barrier } /* * Shootout bench uses affinity to emulate single core processor. This * function searches for appropriate number of threads to spawn. */ static int GetThreadCount() { cpu_set_t cs; int i; int count = 0; CPU_ZERO(&cs); sched_getaffinity(0, sizeof(cs), &cs); for (i = 0; i < 16; i++) if (CPU_ISSET(i, &cs)) count++; return count; } static double spectral_game(int N) { /* Align 64 byte for L2 cache line */ __attribute__((aligned(64))) double u[N]; __attribute__((aligned(64))) double tmp[N]; __attribute__((aligned(64))) double v[N]; double vBv = 0.0; double vv = 0.0; #pragma omp parallel default(shared) num_threads(GetThreadCount()) { int i; #pragma omp for schedule(static) for (i = 0; i < N; i++) u[i] = 1.0; /* * this block will be executed by NUM_THREADS variable declared in this * block is private for each thread */ int threadid = omp_get_thread_num(); int threadcount = omp_get_num_threads(); int chunk = N / threadcount; int ite; struct Param my_param; my_param.tmp = tmp; my_param.N = N; my_param.N2 = N/2; /* * calculate each thread's working range [range1 .. range2) => static * schedule here */ my_param.r_begin = threadid * chunk; my_param.r_end = (threadid < (threadcount -1)) ? (my_param.r_begin + chunk) : N; for (ite = 0; ite < 10; ite++) { my_param.u = u; /* source vec is u */ my_param.v = v; /* destination vec is v */ eval_AtA_times_u(&my_param); my_param.u = v; /* source is v */ my_param.v = u; /* destination is u */ eval_AtA_times_u(&my_param); } /* multi thread adding */ { int i; #pragma omp for schedule(static) reduction( + : vBv, vv ) nowait for (i = 0; i < N; i++) { vv += v[i] * v[i]; vBv += u[i] * v[i]; } } } /* end parallel region */ return sqrt(vBv/vv); } int main(int argc, char *argv[]) { int N = ((argc >= 2) ? atoi(argv[1]) : 2000); printf("%.9f\n", spectral_game(N)); return 0; }
make, command-line, and program output logs
Sat, 27 Apr 2013 21:05:23 GMT MAKE: /usr/bin/gcc -pipe -Wall -O3 -fomit-frame-pointer -march=native -fopenmp -mfpmath=sse -msse2 spectralnorm.gcc-4.c -o spectralnorm.gcc-4.gcc_run -lm rm spectralnorm.gcc-4.c 0.19s to complete and log all make actions COMMAND LINE: ./spectralnorm.gcc-4.gcc_run 5500 PROGRAM OUTPUT: 1.274224153