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38 /* This file is completely threadsafe - keep it that way! */
43 #include "config.h" /* for GMX_MAX_OPENMP_THREADS */
47 #include "gromacs/math/vec.h"
48 #include "gromacs/math/vectypes.h"
49 #include "gromacs/mdlib/gmx_omp_nthreads.h"
50 #include "gromacs/pbcutil/ishift.h"
51 #include "gromacs/pbcutil/pbc.h"
52 #include "gromacs/utility/gmxassert.h"
64 static void upd_vir(rvec vir, real dvx, real dvy, real dvz)
71 static void calc_x_times_f(int nxf, const rvec x[], const rvec f[], gmx_bool bScrewPBC, const matrix box, matrix x_times_f)
75 for (int i = 0; i < nxf; i++)
77 for (int d = 0; d < DIM; d++)
79 for (int n = 0; n < DIM; n++)
81 x_times_f[d][n] += x[i][d] * f[i][n];
87 int isx = gmx::shiftIndexToXDim(i);
88 /* We should correct all odd x-shifts, but the range of isx is -2 to 2 */
89 if (isx == 1 || isx == -1)
91 for (int d = 0; d < DIM; d++)
93 for (int n = 0; n < DIM; n++)
95 x_times_f[d][n] += box[d][d] * f[i][n];
103 void calc_vir(int nxf, const rvec x[], const rvec f[], tensor vir, bool bScrewPBC, const matrix box)
107 int nthreads = gmx_omp_nthreads_get_simple_rvec_task(ModuleMultiThread::Default, nxf * 9);
109 GMX_ASSERT(nthreads >= 1, "Avoids uninitialized x_times_f (warning)");
113 calc_x_times_f(nxf, x, f, bScrewPBC, box, x_times_f);
117 /* Use a buffer on the stack for storing thread-local results.
118 * We use 2 extra elements (=18 reals) per thread to separate thread
119 * local data by at least a cache line. Element 0 is not used.
121 matrix xf_buf[GMX_OPENMP_MAX_THREADS * 3];
123 #pragma omp parallel for num_threads(nthreads) schedule(static)
124 for (int thread = 0; thread < nthreads; thread++)
126 int start = (nxf * thread) / nthreads;
127 int end = std::min(nxf * (thread + 1) / nthreads, nxf);
129 calc_x_times_f(end - start,
134 thread == 0 ? x_times_f : xf_buf[thread * 3]);
137 for (int thread = 1; thread < nthreads; thread++)
139 m_add(x_times_f, xf_buf[thread * 3], x_times_f);
143 for (int d = 0; d < DIM; d++)
145 upd_vir(vir[d], x_times_f[d][XX], x_times_f[d][YY], x_times_f[d][ZZ]);
149 void f_calc_vir(int i0, int i1, const rvec x[], const rvec f[], tensor vir, const matrix box)
151 calc_vir(i1 - i0, x + i0, f + i0, vir, FALSE, box);