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 * This file is part of the GROMACS molecular simulation package.
 *
 * Copyright (c) 1991-2000, University of Groningen, The Netherlands.
 * Copyright (c) 2001-2004, The GROMACS development team.
 * Copyright (c) 2013,2014,2015,2017,2018 by the GROMACS development team.
 * Copyright (c) 2019,2020, by the GROMACS development team, led by
 * Mark Abraham, David van der Spoel, Berk Hess, and Erik Lindahl,
 * and including many others, as listed in the AUTHORS file in the
 * top-level source directory and at http://www.gromacs.org.
 *
 * GROMACS is free software; you can redistribute it and/or
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 * as published by the Free Software Foundation; either version 2.1
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 */
#include "gmxpre.h"

#include "nrnb.h"

#include <cstdlib>
#include <cstring>

#include <algorithm>
#include <vector>

#include "gromacs/mdtypes/commrec.h"
#include "gromacs/mdtypes/md_enums.h"
#include "gromacs/utility/arraysize.h"

typedef struct
{
    const char* name;
    int         flop;
} t_nrnb_data;


static const t_nrnb_data nbdata[eNRNB] = {
    /* These are re-used for different NB kernels, since there are so many.
     * The actual number of flops is set dynamically.
     */
    { "NB VdW [V&F]", 1 },
    { "NB VdW [F]", 1 },
    { "NB Elec. [V&F]", 1 },
    { "NB Elec. [F]", 1 },
    { "NB Elec. [W3,V&F]", 1 },
    { "NB Elec. [W3,F]", 1 },
    { "NB Elec. [W3-W3,V&F]", 1 },
    { "NB Elec. [W3-W3,F]", 1 },
    { "NB Elec. [W4,V&F]", 1 },
    { "NB Elec. [W4,F]", 1 },
    { "NB Elec. [W4-W4,V&F]", 1 },
    { "NB Elec. [W4-W4,F]", 1 },
    { "NB VdW & Elec. [V&F]", 1 },
    { "NB VdW & Elec. [F]", 1 },
    { "NB VdW & Elec. [W3,V&F]", 1 },
    { "NB VdW & Elec. [W3,F]", 1 },
    { "NB VdW & Elec. [W3-W3,V&F]", 1 },
    { "NB VdW & Elec. [W3-W3,F]", 1 },
    { "NB VdW & Elec. [W4,V&F]", 1 },
    { "NB VdW & Elec. [W4,F]", 1 },
    { "NB VdW & Elec. [W4-W4,V&F]", 1 },
    { "NB VdW & Elec. [W4-W4,F]", 1 },

    { "NB Generic kernel", 1 },
    { "NB Generic charge grp kernel", 1 },
    { "NB Free energy kernel", 1 },

    { "Pair Search distance check", 9 }, /* nbnxn pair dist. check */
    /* nbnxn kernel flops are based on inner-loops without exclusion checks.
     * Plain Coulomb runs through the RF kernels, except with GPUs.
     * invsqrt is counted as 6 flops: 1 for _mm_rsqt_ps + 5 for iteration.
     * The flops are equal for plain-C, x86 SIMD and GPUs, except for:
     * - plain-C kernel uses one flop more for Coulomb-only (F) than listed
     * - x86 SIMD LJ geom-comb.rule kernels (fastest) use 2 more flops
     * - x86 SIMD LJ LB-comb.rule kernels (fast) use 3 (8 for F+E) more flops
     * - GPU always does exclusions, which requires 2-4 flops, but as invsqrt
     *   is always counted as 6 flops, this roughly compensates.
     */
    { "NxN RF Elec. + LJ [F]", 38 }, /* nbnxn kernel LJ+RF, no ener */
    { "NxN RF Elec. + LJ [V&F]", 54 },
    { "NxN QSTab Elec. + LJ [F]", 41 }, /* nbnxn kernel LJ+tab, no en */
    { "NxN QSTab Elec. + LJ [V&F]", 59 },
    { "NxN Ewald Elec. + LJ [F]", 66 }, /* nbnxn kernel LJ+Ewald, no en */
    { "NxN Ewald Elec. + LJ [V&F]", 107 },
    { "NxN LJ [F]", 33 }, /* nbnxn kernel LJ, no ener */
    { "NxN LJ [V&F]", 43 },
    { "NxN RF Electrostatics [F]", 31 }, /* nbnxn kernel RF, no ener */
    { "NxN RF Electrostatics [V&F]", 36 },
    { "NxN QSTab Elec. [F]", 34 }, /* nbnxn kernel tab, no ener */
    { "NxN QSTab Elec. [V&F]", 41 },
    { "NxN Ewald Elec. [F]", 61 }, /* nbnxn kernel Ewald, no ener */
    { "NxN Ewald Elec. [V&F]", 84 },
    /* The switch function flops should be added to the LJ kernels above */
    { "NxN LJ add F-switch [F]", 12 }, /* extra cost for LJ F-switch */
    { "NxN LJ add F-switch [V&F]", 22 },
    { "NxN LJ add P-switch [F]", 27 }, /* extra cost for LJ P-switch */
    { "NxN LJ add P-switch [V&F]", 20 },
    { "NxN LJ add LJ Ewald [F]", 36 }, /* extra cost for LJ Ewald */
    { "NxN LJ add LJ Ewald [V&F]", 33 },
    { "1,4 nonbonded interactions", 90 },
    { "Calc Weights", 36 },
    { "Spread Q", 6 },
    { "Spread Q Bspline", 2 },
    { "Gather F", 23 },
    { "Gather F Bspline", 6 },
    { "3D-FFT", 8 },
    { "Convolution", 4 },
    { "Solve PME", 64 },
    { "NS-Pairs", 21 },
    { "Reset In Box", 3 },
    { "Shift-X", 6 },
    { "CG-CoM", 3 },
    { "Sum Forces", 1 },
    { "Bonds", 59 },
    { "G96Bonds", 44 },
    { "FENE Bonds", 58 },
    { "Tab. Bonds", 62 },
    { "Restraint Potential", 86 },
    { "Linear Angles", 57 },
    { "Angles", 168 },
    { "G96Angles", 150 },
    { "Quartic Angles", 160 },
    { "Tab. Angles", 169 },
    { "Propers", 229 },
    { "Impropers", 208 },
    { "RB-Dihedrals", 247 },
    { "Four. Dihedrals", 247 },
    { "Tab. Dihedrals", 227 },
    { "Dist. Restr.", 200 },
    { "Orient. Restr.", 200 },
    { "Dihedral Restr.", 200 },
    { "Pos. Restr.", 50 },
    { "Flat-bottom posres", 50 },
    { "Angle Restr.", 191 },
    { "Angle Restr. Z", 164 },
    { "Morse Potent.", 83 },
    { "Cubic Bonds", 54 },
    { "Walls", 31 },
    { "Polarization", 59 },
    { "Anharmonic Polarization", 72 },
    { "Water Pol.", 62 },
    { "Thole Pol.", 296 },
    { "Virial", 18 },
    { "Update", 31 },
    { "Ext.ens. Update", 54 },
    { "Stop-CM", 10 },
    { "P-Coupling", 6 },
    { "Calc-Ekin", 27 },
    { "Lincs", 60 },
    { "Lincs-Mat", 4 },
    { "Shake", 30 },
    { "Constraint-V", 9 },
    { "Shake-Init", 10 },
    { "Constraint-Vir", 24 },
    { "Settle", 370 },
    { "Virtual Site 1", 1 },
    { "Virtual Site 2", 23 },
    { "Virtual Site 2fd", 63 },
    { "Virtual Site 3", 37 },
    { "Virtual Site 3fd", 95 },
    { "Virtual Site 3fad", 176 },
    { "Virtual Site 3out", 87 },
    { "Virtual Site 4fd", 110 },
    { "Virtual Site 4fdn", 254 },
    { "Virtual Site N", 15 },
    { "CMAP", 1700 }, // Estimate!
    { "Urey-Bradley", 183 },
    { "Cross-Bond-Bond", 163 },
    { "Cross-Bond-Angle", 163 }
};

static void pr_two(FILE* out, int c, int i)
{
    if (i < 10)
    {
        fprintf(out, "%c0%1d", c, i);
    }
    else
    {
        fprintf(out, "%c%2d", c, i);
    }
}

static void pr_difftime(FILE* out, double dt)
{
    int      ndays, nhours, nmins, nsecs;
    gmx_bool bPrint, bPrinted;

    ndays    = static_cast<int>(dt / (24 * 3600));
    dt       = dt - 24 * 3600 * ndays;
    nhours   = static_cast<int>(dt / 3600);
    dt       = dt - 3600 * nhours;
    nmins    = static_cast<int>(dt / 60);
    dt       = dt - nmins * 60;
    nsecs    = static_cast<int>(dt);
    bPrint   = (ndays > 0);
    bPrinted = bPrint;
    if (bPrint)
    {
        fprintf(out, "%d", ndays);
    }
    bPrint = bPrint || (nhours > 0);
    if (bPrint)
    {
        if (bPrinted)
        {
            pr_two(out, 'd', nhours);
        }
        else
        {
            fprintf(out, "%d", nhours);
        }
    }
    bPrinted = bPrinted || bPrint;
    bPrint   = bPrint || (nmins > 0);
    if (bPrint)
    {
        if (bPrinted)
        {
            pr_two(out, 'h', nmins);
        }
        else
        {
            fprintf(out, "%d", nmins);
        }
    }
    bPrinted = bPrinted || bPrint;
    if (bPrinted)
    {
        pr_two(out, ':', nsecs);
    }
    else
    {
        fprintf(out, "%ds", nsecs);
    }
    fprintf(out, "\n");
}

void clear_nrnb(t_nrnb* nrnb)
{
    int i;

    for (i = 0; (i < eNRNB); i++)
    {
        nrnb->n[i] = 0.0;
    }
}

void add_nrnb(t_nrnb* dest, t_nrnb* s1, t_nrnb* s2)
{
    int i;

    for (i = 0; (i < eNRNB); i++)
    {
        dest->n[i] = s1->n[i] + s2->n[i];
    }
}

void print_nrnb(FILE* out, t_nrnb* nrnb)
{
    int i;

    for (i = 0; (i < eNRNB); i++)
    {
        if (nrnb->n[i] > 0)
        {
            fprintf(out, " %-26s %10.0f.\n", nbdata[i].name, nrnb->n[i]);
        }
    }
}

void _inc_nrnb(t_nrnb* nrnb, int enr, int inc, char gmx_unused* file, int gmx_unused line)
{
    nrnb->n[enr] += inc;
#ifdef DEBUG_NRNB
    printf("nrnb %15s(%2d) incremented with %8d from file %s line %d\n", nbdata[enr].name, enr, inc,
           file, line);
#endif
}

/* Returns in enr is the index of a full nbnxn VdW kernel */
static gmx_bool nrnb_is_nbnxn_vdw_kernel(int enr)
{
    return (enr >= eNR_NBNXN_LJ_RF && enr <= eNR_NBNXN_LJ_E);
}

/* Returns in enr is the index of an nbnxn kernel addition (LJ modification) */
static gmx_bool nrnb_is_nbnxn_kernel_addition(int enr)
{
    return (enr >= eNR_NBNXN_ADD_LJ_FSW && enr <= eNR_NBNXN_ADD_LJ_EWALD_E);
}

void print_flop(FILE* out, t_nrnb* nrnb, double* nbfs, double* mflop)
{
    int         i, j;
    double      mni, frac, tfrac, tflop;
    const char* myline =
            "-----------------------------------------------------------------------------";

    *nbfs = 0.0;
    for (i = 0; (i < eNR_NBKERNEL_TOTAL_NR); i++)
    {
        if (std::strstr(nbdata[i].name, "W3-W3") != nullptr)
        {
            *nbfs += 9e-6 * nrnb->n[i];
        }
        else if (std::strstr(nbdata[i].name, "W3") != nullptr)
        {
            *nbfs += 3e-6 * nrnb->n[i];
        }
        else if (std::strstr(nbdata[i].name, "W4-W4") != nullptr)
        {
            *nbfs += 10e-6 * nrnb->n[i];
        }
        else if (std::strstr(nbdata[i].name, "W4") != nullptr)
        {
            *nbfs += 4e-6 * nrnb->n[i];
        }
        else
        {
            *nbfs += 1e-6 * nrnb->n[i];
        }
    }
    tflop = 0;
    for (i = 0; (i < eNRNB); i++)
    {
        tflop += 1e-6 * nrnb->n[i] * nbdata[i].flop;
    }

    if (tflop == 0)
    {
        fprintf(out, "No MEGA Flopsen this time\n");
        return;
    }
    if (out)
    {
        fprintf(out, "\n\tM E G A - F L O P S   A C C O U N T I N G\n\n");
    }

    if (out)
    {
        fprintf(out, " NB=Group-cutoff nonbonded kernels    NxN=N-by-N cluster Verlet kernels\n");
        fprintf(out, " RF=Reaction-Field  VdW=Van der Waals  QSTab=quadratic-spline table\n");
        fprintf(out, " W3=SPC/TIP3p  W4=TIP4p (single or pairs)\n");
        fprintf(out, " V&F=Potential and force  V=Potential only  F=Force only\n\n");

        fprintf(out, " %-32s %16s %15s  %7s\n", "Computing:", "M-Number", "M-Flops", "% Flops");
        fprintf(out, "%s\n", myline);
    }
    *mflop = 0.0;
    tfrac  = 0.0;
    for (i = 0; (i < eNRNB); i++)
    {
        mni = 1e-6 * nrnb->n[i];
        /* Skip empty entries and nbnxn additional flops,
         * which have been added to the kernel entry.
         */
        if (mni > 0 && !nrnb_is_nbnxn_kernel_addition(i))
        {
            int flop;

            flop = nbdata[i].flop;
            if (nrnb_is_nbnxn_vdw_kernel(i))
            {
                /* Possibly add the cost of an LJ switch/Ewald function */
                for (j = eNR_NBNXN_ADD_LJ_FSW; j <= eNR_NBNXN_ADD_LJ_EWALD; j += 2)
                {
                    int e_kernel_add;

                    /* Select the force or energy flop count */
                    e_kernel_add = j + ((i - eNR_NBNXN_LJ_RF) % 2);

                    if (nrnb->n[e_kernel_add] > 0)
                    {
                        flop += nbdata[e_kernel_add].flop;
                    }
                }
            }
            *mflop += mni * flop;
            frac = 100.0 * mni * flop / tflop;
            tfrac += frac;
            if (out != nullptr)
            {
                fprintf(out, " %-32s %16.6f %15.3f  %6.1f\n", nbdata[i].name, mni, mni * flop, frac);
            }
        }
    }
    if (out)
    {
        fprintf(out, "%s\n", myline);
        fprintf(out, " %-32s %16s %15.3f  %6.1f\n", "Total", "", *mflop, tfrac);
        fprintf(out, "%s\n\n", myline);

        if (nrnb->n[eNR_NBKERNEL_GENERIC] > 0)
        {
            fprintf(out,
                    "WARNING: Using the slow generic C kernel. This is fine if you are\n"
                    "comparing different implementations or MD software. Routine\n"
                    "simulations should use a different non-bonded setup for much better\n"
                    "performance.\n\n");
        }
    }
}

void print_perf(FILE*   out,
                double  time_per_thread,
                double  time_per_node,
                int64_t nsteps,
                double  delta_t,
                double  nbfs,
                double  mflop)
{
    double wallclocktime;

    fprintf(out, "\n");

    if (time_per_node > 0)
    {
        fprintf(out, "%12s %12s %12s %10s\n", "", "Core t (s)", "Wall t (s)", "(%)");
        fprintf(out, "%12s %12.3f %12.3f %10.1f\n", "Time:", time_per_thread, time_per_node,
                100.0 * time_per_thread / time_per_node);
        /* only print day-hour-sec format if time_per_node is more than 30 min */
        if (time_per_node > 30 * 60)
        {
            fprintf(out, "%12s %12s", "", "");
            pr_difftime(out, time_per_node);
        }
        if (delta_t > 0)
        {
            mflop         = mflop / time_per_node;
            wallclocktime = nsteps * delta_t;

            if (getenv("GMX_DETAILED_PERF_STATS") == nullptr)
            {
                fprintf(out, "%12s %12s %12s\n", "", "(ns/day)", "(hour/ns)");
                fprintf(out, "%12s %12.3f %12.3f\n", "Performance:", wallclocktime * 24 * 3.6 / time_per_node,
                        1000 * time_per_node / (3600 * wallclocktime));
            }
            else
            {
                fprintf(out, "%12s %12s %12s %12s %12s\n", "", "(Mnbf/s)",
                        (mflop > 1000) ? "(GFlops)" : "(MFlops)", "(ns/day)", "(hour/ns)");
                fprintf(out, "%12s %12.3f %12.3f %12.3f %12.3f\n", "Performance:", nbfs / time_per_node,
                        (mflop > 1000) ? (mflop / 1000) : mflop, wallclocktime * 24 * 3.6 / time_per_node,
                        1000 * time_per_node / (3600 * wallclocktime));
            }
        }
        else
        {
            if (getenv("GMX_DETAILED_PERF_STATS") == nullptr)
            {
                fprintf(out, "%12s %14s\n", "", "(steps/hour)");
                fprintf(out, "%12s %14.1f\n", "Performance:", nsteps * 3600.0 / time_per_node);
            }
            else
            {
                fprintf(out, "%12s %12s %12s %14s\n", "", "(Mnbf/s)",
                        (mflop > 1000) ? "(GFlops)" : "(MFlops)", "(steps/hour)");
                fprintf(out, "%12s %12.3f %12.3f %14.1f\n", "Performance:", nbfs / time_per_node,
                        (mflop > 1000) ? (mflop / 1000) : mflop, nsteps * 3600.0 / time_per_node);
            }
        }
    }
}

int cost_nrnb(int enr)
{
    return nbdata[enr].flop;
}

const char* nrnb_str(int enr)
{
    return nbdata[enr].name;
}

static const int force_index[] = {
    eNR_BONDS,  eNR_ANGLES, eNR_PROPER, eNR_IMPROPER, eNR_RB,
    eNR_DISRES, eNR_ORIRES, eNR_POSRES, eNR_FBPOSRES, eNR_NS,
};
#define NFORCE_INDEX asize(force_index)

static const int constr_index[] = { eNR_SHAKE,  eNR_SHAKE_RIJ,  eNR_SETTLE,  eNR_UPDATE,
                                    eNR_PCOUPL, eNR_CONSTR_VIR, eNR_CONSTR_V };
#define NCONSTR_INDEX asize(constr_index)

static double pr_av(FILE* log, t_commrec* cr, double fav, const double ftot[], const char* title)
{
    int    i, perc;
    double dperc, unb;

    unb = 0;
    if (fav > 0)
    {
        fav /= cr->nnodes - cr->npmenodes;
        fprintf(log, "\n %-26s", title);
        for (i = 0; (i < cr->nnodes); i++)
        {
            dperc = (100.0 * ftot[i]) / fav;
            unb   = std::max(unb, dperc);
            perc  = static_cast<int>(dperc);
            fprintf(log, "%3d ", perc);
        }
        if (unb > 0)
        {
            perc = static_cast<int>(10000.0 / unb);
            fprintf(log, "%6d%%\n\n", perc);
        }
        else
        {
            fprintf(log, "\n\n");
        }
    }
    return unb;
}

void pr_load(FILE* log, t_commrec* cr, t_nrnb nrnb[])
{
    t_nrnb av;

    std::vector<double> ftot(cr->nnodes);
    std::vector<double> stot(cr->nnodes);
    for (int i = 0; (i < cr->nnodes); i++)
    {
        add_nrnb(&av, &av, &(nrnb[i]));
        /* Cost due to forces */
        for (int j = 0; (j < eNR_NBKERNEL_TOTAL_NR); j++)
        {
            ftot[i] += nrnb[i].n[j] * cost_nrnb(j);
        }
        for (int j = 0; (j < NFORCE_INDEX); j++)
        {
            ftot[i] += nrnb[i].n[force_index[j]] * cost_nrnb(force_index[j]);
        }
        /* Due to shake */
        for (int j = 0; (j < NCONSTR_INDEX); j++)
        {
            stot[i] += nrnb[i].n[constr_index[j]] * cost_nrnb(constr_index[j]);
        }
    }
    for (int j = 0; (j < eNRNB); j++)
    {
        av.n[j] = av.n[j] / static_cast<double>(cr->nnodes - cr->npmenodes);
    }

    fprintf(log, "\nDetailed load balancing info in percentage of average\n");

    fprintf(log, " Type                 RANK:");
    for (int i = 0; (i < cr->nnodes); i++)
    {
        fprintf(log, "%3d ", i);
    }
    fprintf(log, "Scaling\n");
    fprintf(log, "---------------------------");
    for (int i = 0; (i < cr->nnodes); i++)
    {
        fprintf(log, "----");
    }
    fprintf(log, "-------\n");

    for (int j = 0; (j < eNRNB); j++)
    {
        double unb = 100.0;
        if (av.n[j] > 0)
        {
            double dperc;
            int    perc;
            fprintf(log, " %-26s", nrnb_str(j));
            for (int i = 0; (i < cr->nnodes); i++)
            {
                dperc = (100.0 * nrnb[i].n[j]) / av.n[j];
                unb   = std::max(unb, dperc);
                perc  = static_cast<int>(dperc);
                fprintf(log, "%3d ", perc);
            }
            if (unb > 0)
            {
                perc = static_cast<int>(10000.0 / unb);
                fprintf(log, "%6d%%\n", perc);
            }
            else
            {
                fprintf(log, "\n");
            }
        }
    }
    double fav = 0;
    double sav = 0;
    for (int i = 0; (i < cr->nnodes); i++)
    {
        fav += ftot[i];
        sav += stot[i];
    }
    double uf = pr_av(log, cr, fav, ftot.data(), "Total Force");
    double us = pr_av(log, cr, sav, stot.data(), "Total Constr.");

    double unb = (uf * fav + us * sav) / (fav + sav);
    if (unb > 0)
    {
        unb = 10000.0 / unb;
        fprintf(log, "\nTotal Scaling: %.0f%% of max performance\n\n", unb);
    }
}
