gmx_bool pme_load_balance(pme_load_balancing_t       pme_lb,
                          t_commrec                 *cr,
                          FILE                      *fp_err,
                          FILE                      *fp_log,
                          t_inputrec                *ir,
                          t_state                   *state,
                          double                     cycles,
                          interaction_const_t       *ic,
                          struct nonbonded_verlet_t *nbv,
                          struct gmx_pme_t **        pmedata,
                          gmx_int64_t                step)
{
    gmx_bool     OK;
    pme_setup_t *set;
    double       cycles_fast;
    char         buf[STRLEN], sbuf[22];
    real         rtab;
    gmx_bool     bUsesSimpleTables = TRUE;

    if (pme_lb->stage == pme_lb->nstage)
    {
        return FALSE;
    }

    if (PAR(cr))
    {
        gmx_sumd(1, &cycles, cr);
        cycles /= cr->nnodes;
    }

    set = &pme_lb->setup[pme_lb->cur];
    set->count++;

    rtab = ir->rlistlong + ir->tabext;

    if (set->count % 2 == 1)
    {
        /* Skip the first cycle, because the first step after a switch
         * is much slower due to allocation and/or caching effects.
         */
        return TRUE;
    }

    sprintf(buf, "step %4s: ", gmx_step_str(step, sbuf));
    print_grid(fp_err, fp_log, buf, "timed with", set, cycles);

    if (set->count <= 2)
    {
        set->cycles = cycles;
    }
    else
    {
        if (cycles*PME_LB_ACCEL_TOL < set->cycles &&
            pme_lb->stage == pme_lb->nstage - 1)
        {
            /* The performance went up a lot (due to e.g. DD load balancing).
             * Add a stage, keep the minima, but rescan all setups.
             */
            pme_lb->nstage++;

            if (debug)
            {
                fprintf(debug, "The performance for grid %d %d %d went from %.3f to %.1f M-cycles, this is more than %f\n"
                        "Increased the number stages to %d"
                        " and ignoring the previous performance\n",
                        set->grid[XX], set->grid[YY], set->grid[ZZ],
                        cycles*1e-6, set->cycles*1e-6, PME_LB_ACCEL_TOL,
                        pme_lb->nstage);
            }
        }
        set->cycles = min(set->cycles, cycles);
    }

    if (set->cycles < pme_lb->setup[pme_lb->fastest].cycles)
    {
        pme_lb->fastest = pme_lb->cur;

        if (DOMAINDECOMP(cr))
        {
            /* We found a new fastest setting, ensure that with subsequent
             * shorter cut-off's the dynamic load balancing does not make
             * the use of the current cut-off impossible. This solution is
             * a trade-off, as the PME load balancing and DD domain size
             * load balancing can interact in complex ways.
             * With the Verlet kernels, DD load imbalance will usually be
             * mainly due to bonded interaction imbalance, which will often
             * quickly push the domain boundaries beyond the limit for the
             * optimal, PME load balanced, cut-off. But it could be that
             * better overal performance can be obtained with a slightly
             * shorter cut-off and better DD load balancing.
             */
            change_dd_dlb_cutoff_limit(cr);
        }
    }
    cycles_fast = pme_lb->setup[pme_lb->fastest].cycles;

    /* Check in stage 0 if we should stop scanning grids.
     * Stop when the time is more than SLOW_FAC longer than the fastest.
     */
    if (pme_lb->stage == 0 && pme_lb->cur > 0 &&
        cycles > pme_lb->setup[pme_lb->fastest].cycles*PME_LB_SLOW_FAC)
    {
        pme_lb->n = pme_lb->cur + 1;
        /* Done with scanning, go to stage 1 */
        switch_to_stage1(pme_lb);
    }

    if (pme_lb->stage == 0)
    {
        int gridsize_start;

        gridsize_start = set->grid[XX]*set->grid[YY]*set->grid[ZZ];

        do
        {
            if (pme_lb->cur+1 < pme_lb->n)
            {
                /* We had already generated the next setup */
                OK = TRUE;
            }
            else
            {
                /* Find the next setup */
                OK = pme_loadbal_increase_cutoff(pme_lb, ir->pme_order, cr->dd);

                if (!OK)
                {
                    pme_lb->elimited = epmelblimPMEGRID;
                }
            }

            if (OK && ir->ePBC != epbcNONE)
            {
                OK = (sqr(pme_lb->setup[pme_lb->cur+1].rlistlong)
                      <= max_cutoff2(ir->ePBC, state->box));
                if (!OK)
                {
                    pme_lb->elimited = epmelblimBOX;
                }
            }

            if (OK)
            {
                pme_lb->cur++;

                if (DOMAINDECOMP(cr))
                {
                    OK = change_dd_cutoff(cr, state, ir,
                                          pme_lb->setup[pme_lb->cur].rlistlong);
                    if (!OK)
                    {
                        /* Failed: do not use this setup */
                        pme_lb->cur--;
                        pme_lb->elimited = epmelblimDD;
                    }
                }
            }
            if (!OK)
            {
                /* We hit the upper limit for the cut-off,
                 * the setup should not go further than cur.
                 */
                pme_lb->n = pme_lb->cur + 1;
                print_loadbal_limited(fp_err, fp_log, step, pme_lb);
                /* Switch to the next stage */
                switch_to_stage1(pme_lb);
            }
        }
        while (OK &&
               !(pme_lb->setup[pme_lb->cur].grid[XX]*
                 pme_lb->setup[pme_lb->cur].grid[YY]*
                 pme_lb->setup[pme_lb->cur].grid[ZZ] <
                 gridsize_start*PME_LB_GRID_SCALE_FAC
                 &&
                 pme_lb->setup[pme_lb->cur].grid_efficiency <
                 pme_lb->setup[pme_lb->cur-1].grid_efficiency*PME_LB_GRID_EFFICIENCY_REL_FAC));
    }

    if (pme_lb->stage > 0 && pme_lb->end == 1)
    {
        pme_lb->cur   = 0;
        pme_lb->stage = pme_lb->nstage;
    }
    else if (pme_lb->stage > 0 && pme_lb->end > 1)
    {
        /* If stage = nstage-1:
         *   scan over all setups, rerunning only those setups
         *   which are not much slower than the fastest
         * else:
         *   use the next setup
         */
        do
        {
            pme_lb->cur++;
            if (pme_lb->cur == pme_lb->end)
            {
                pme_lb->stage++;
                pme_lb->cur = pme_lb->start;
            }
        }
        while (pme_lb->stage == pme_lb->nstage - 1 &&
               pme_lb->setup[pme_lb->cur].count > 0 &&
               pme_lb->setup[pme_lb->cur].cycles > cycles_fast*PME_LB_SLOW_FAC);

        if (pme_lb->stage == pme_lb->nstage)
        {
            /* We are done optimizing, use the fastest setup we found */
            pme_lb->cur = pme_lb->fastest;
        }
    }

    if (DOMAINDECOMP(cr) && pme_lb->stage > 0)
    {
        OK = change_dd_cutoff(cr, state, ir, pme_lb->setup[pme_lb->cur].rlistlong);
        if (!OK)
        {
            /* Failsafe solution */
            if (pme_lb->cur > 1 && pme_lb->stage == pme_lb->nstage)
            {
                pme_lb->stage--;
            }
            pme_lb->fastest  = 0;
            pme_lb->start    = 0;
            pme_lb->end      = pme_lb->cur;
            pme_lb->cur      = pme_lb->start;
            pme_lb->elimited = epmelblimDD;
            print_loadbal_limited(fp_err, fp_log, step, pme_lb);
        }
    }

    /* Change the Coulomb cut-off and the PME grid */

    set = &pme_lb->setup[pme_lb->cur];

    ic->rcoulomb     = set->rcut_coulomb;
    ic->rlist        = set->rlist;
    ic->rlistlong    = set->rlistlong;
    ir->nstcalclr    = set->nstcalclr;
    ic->ewaldcoeff_q = set->ewaldcoeff_q;
    /* TODO: centralize the code that sets the potentials shifts */
    if (ic->coulomb_modifier == eintmodPOTSHIFT)
    {
        ic->sh_ewald = gmx_erfc(ic->ewaldcoeff_q*ic->rcoulomb);
    }
    if (EVDW_PME(ic->vdwtype))
    {
        /* We have PME for both Coulomb and VdW, set rvdw equal to rcoulomb */
        ic->rvdw            = set->rcut_coulomb;
        ic->ewaldcoeff_lj   = set->ewaldcoeff_lj;
        if (ic->vdw_modifier == eintmodPOTSHIFT)
        {
            real crc2;

            ic->dispersion_shift.cpot = -pow(ic->rvdw, -6.0);
            ic->repulsion_shift.cpot  = -pow(ic->rvdw, -12.0);
            ic->sh_invrc6             = -ic->dispersion_shift.cpot;
            crc2                      = sqr(ic->ewaldcoeff_lj*ic->rvdw);
            ic->sh_lj_ewald           = (exp(-crc2)*(1 + crc2 + 0.5*crc2*crc2) - 1)*pow(ic->rvdw, -6.0);
        }
    }

    bUsesSimpleTables = uses_simple_tables(ir->cutoff_scheme, nbv, 0);
    nbnxn_gpu_pme_loadbal_update_param(nbv, ic);

    /* With tMPI + GPUs some ranks may be sharing GPU(s) and therefore
     * also sharing texture references. To keep the code simple, we don't
     * treat texture references as shared resources, but this means that
     * the coulomb_tab texture ref will get updated by multiple threads.
     * Hence, to ensure that the non-bonded kernels don't start before all
     * texture binding operations are finished, we need to wait for all ranks
     * to arrive here before continuing.
     *
     * Note that we could omit this barrier if GPUs are not shared (or
     * texture objects are used), but as this is initialization code, there
     * is not point in complicating things.
     */
#ifdef GMX_THREAD_MPI
    if (PAR(cr) && use_GPU(nbv))
    {
        gmx_barrier(cr);
    }
#endif  /* GMX_THREAD_MPI */

    /* Usually we won't need the simple tables with GPUs.
     * But we do with hybrid acceleration and with free energy.
     * To avoid bugs, we always re-initialize the simple tables here.
     */
    init_interaction_const_tables(NULL, ic, bUsesSimpleTables, rtab);

    if (cr->duty & DUTY_PME)
    {
        if (pme_lb->setup[pme_lb->cur].pmedata == NULL)
        {
            /* Generate a new PME data structure,
             * copying part of the old pointers.
             */
            gmx_pme_reinit(&set->pmedata,
                           cr, pme_lb->setup[0].pmedata, ir,
                           set->grid);
        }
        *pmedata = set->pmedata;
    }
    else
    {
        /* Tell our PME-only node to switch grid */
        gmx_pme_send_switchgrid(cr, set->grid, set->ewaldcoeff_q, set->ewaldcoeff_lj);
    }

    if (debug)
    {
        print_grid(NULL, debug, "", "switched to", set, -1);
    }

    if (pme_lb->stage == pme_lb->nstage)
    {
        print_grid(fp_err, fp_log, "", "optimal", set, -1);
    }

    return TRUE;
}
示例#2
0
gmx_bool pme_load_balance(pme_load_balancing_t pme_lb,
                          t_commrec           *cr,
                          FILE                *fp_err,
                          FILE                *fp_log,
                          t_inputrec          *ir,
                          t_state             *state,
                          double               cycles,
                          interaction_const_t *ic,
                          nonbonded_verlet_t  *nbv,
                          gmx_pme_t           *pmedata,
                          gmx_large_int_t      step)
{
    gmx_bool     OK;
    pme_setup_t *set;
    double       cycles_fast;
    char         buf[STRLEN], sbuf[22];
    real         rtab;
    gmx_bool     bUsesSimpleTables = TRUE;

    if (pme_lb->stage == pme_lb->nstage)
    {
        return FALSE;
    }

    if (PAR(cr))
    {
        gmx_sumd(1, &cycles, cr);
        cycles /= cr->nnodes;
    }

    set = &pme_lb->setup[pme_lb->cur];
    set->count++;

    rtab = ir->rlistlong + ir->tabext;

    if (set->count % 2 == 1)
    {
        /* Skip the first cycle, because the first step after a switch
         * is much slower due to allocation and/or caching effects.
         */
        return TRUE;
    }

    sprintf(buf, "step %4s: ", gmx_step_str(step, sbuf));
    print_grid(fp_err, fp_log, buf, "timed with", set, cycles);

    if (set->count <= 2)
    {
        set->cycles = cycles;
    }
    else
    {
        if (cycles*PME_LB_ACCEL_TOL < set->cycles &&
            pme_lb->stage == pme_lb->nstage - 1)
        {
            /* The performance went up a lot (due to e.g. DD load balancing).
             * Add a stage, keep the minima, but rescan all setups.
             */
            pme_lb->nstage++;

            if (debug)
            {
                fprintf(debug, "The performance for grid %d %d %d went from %.3f to %.1f M-cycles, this is more than %f\n"
                        "Increased the number stages to %d"
                        " and ignoring the previous performance\n",
                        set->grid[XX], set->grid[YY], set->grid[ZZ],
                        cycles*1e-6, set->cycles*1e-6, PME_LB_ACCEL_TOL,
                        pme_lb->nstage);
            }
        }
        set->cycles = min(set->cycles, cycles);
    }

    if (set->cycles < pme_lb->setup[pme_lb->fastest].cycles)
    {
        pme_lb->fastest = pme_lb->cur;

        if (DOMAINDECOMP(cr))
        {
            /* We found a new fastest setting, ensure that with subsequent
             * shorter cut-off's the dynamic load balancing does not make
             * the use of the current cut-off impossible. This solution is
             * a trade-off, as the PME load balancing and DD domain size
             * load balancing can interact in complex ways.
             * With the Verlet kernels, DD load imbalance will usually be
             * mainly due to bonded interaction imbalance, which will often
             * quickly push the domain boundaries beyond the limit for the
             * optimal, PME load balanced, cut-off. But it could be that
             * better overal performance can be obtained with a slightly
             * shorter cut-off and better DD load balancing.
             */
            change_dd_dlb_cutoff_limit(cr);
        }
    }
    cycles_fast = pme_lb->setup[pme_lb->fastest].cycles;

    /* Check in stage 0 if we should stop scanning grids.
     * Stop when the time is more than SLOW_FAC longer than the fastest.
     */
    if (pme_lb->stage == 0 && pme_lb->cur > 0 &&
        cycles > pme_lb->setup[pme_lb->fastest].cycles*PME_LB_SLOW_FAC)
    {
        pme_lb->n = pme_lb->cur + 1;
        /* Done with scanning, go to stage 1 */
        switch_to_stage1(pme_lb);
    }

    if (pme_lb->stage == 0)
    {
        int gridsize_start;

        gridsize_start = set->grid[XX]*set->grid[YY]*set->grid[ZZ];

        do
        {
            if (pme_lb->cur+1 < pme_lb->n)
            {
                /* We had already generated the next setup */
                OK = TRUE;
            }
            else
            {
                /* Find the next setup */
                OK = pme_loadbal_increase_cutoff(pme_lb, ir->pme_order);
            }

            if (OK && ir->ePBC != epbcNONE)
            {
                OK = (sqr(pme_lb->setup[pme_lb->cur+1].rlistlong)
                      <= max_cutoff2(ir->ePBC, state->box));
                if (!OK)
                {
                    pme_lb->elimited = epmelblimBOX;
                }
            }

            if (OK)
            {
                pme_lb->cur++;

                if (DOMAINDECOMP(cr))
                {
                    OK = change_dd_cutoff(cr, state, ir,
                                          pme_lb->setup[pme_lb->cur].rlistlong);
                    if (!OK)
                    {
                        /* Failed: do not use this setup */
                        pme_lb->cur--;
                        pme_lb->elimited = epmelblimDD;
                    }
                }
            }
            if (!OK)
            {
                /* We hit the upper limit for the cut-off,
                 * the setup should not go further than cur.
                 */
                pme_lb->n = pme_lb->cur + 1;
                print_loadbal_limited(fp_err, fp_log, step, pme_lb);
                /* Switch to the next stage */
                switch_to_stage1(pme_lb);
            }
        }
        while (OK &&
               !(pme_lb->setup[pme_lb->cur].grid[XX]*
                 pme_lb->setup[pme_lb->cur].grid[YY]*
                 pme_lb->setup[pme_lb->cur].grid[ZZ] <
                 gridsize_start*PME_LB_GRID_SCALE_FAC
                 &&
                 pme_lb->setup[pme_lb->cur].grid_efficiency <
                 pme_lb->setup[pme_lb->cur-1].grid_efficiency*PME_LB_GRID_EFFICIENCY_REL_FAC));
    }

    if (pme_lb->stage > 0 && pme_lb->end == 1)
    {
        pme_lb->cur   = 0;
        pme_lb->stage = pme_lb->nstage;
    }
    else if (pme_lb->stage > 0 && pme_lb->end > 1)
    {
        /* If stage = nstage-1:
         *   scan over all setups, rerunning only those setups
         *   which are not much slower than the fastest
         * else:
         *   use the next setup
         */
        do
        {
            pme_lb->cur++;
            if (pme_lb->cur == pme_lb->end)
            {
                pme_lb->stage++;
                pme_lb->cur = pme_lb->start;
            }
        }
        while (pme_lb->stage == pme_lb->nstage - 1 &&
               pme_lb->setup[pme_lb->cur].count > 0 &&
               pme_lb->setup[pme_lb->cur].cycles > cycles_fast*PME_LB_SLOW_FAC);

        if (pme_lb->stage == pme_lb->nstage)
        {
            /* We are done optimizing, use the fastest setup we found */
            pme_lb->cur = pme_lb->fastest;
        }
    }

    if (DOMAINDECOMP(cr) && pme_lb->stage > 0)
    {
        OK = change_dd_cutoff(cr, state, ir, pme_lb->setup[pme_lb->cur].rlistlong);
        if (!OK)
        {
            /* Failsafe solution */
            if (pme_lb->cur > 1 && pme_lb->stage == pme_lb->nstage)
            {
                pme_lb->stage--;
            }
            pme_lb->fastest  = 0;
            pme_lb->start    = 0;
            pme_lb->end      = pme_lb->cur;
            pme_lb->cur      = pme_lb->start;
            pme_lb->elimited = epmelblimDD;
            print_loadbal_limited(fp_err, fp_log, step, pme_lb);
        }
    }

    /* Change the Coulomb cut-off and the PME grid */

    set = &pme_lb->setup[pme_lb->cur];

    ic->rcoulomb   = set->rcut_coulomb;
    ic->rlist      = set->rlist;
    ic->rlistlong  = set->rlistlong;
    ir->nstcalclr  = set->nstcalclr;
    ic->ewaldcoeff = set->ewaldcoeff;

    bUsesSimpleTables = uses_simple_tables(ir->cutoff_scheme, nbv, 0);
    if (pme_lb->cutoff_scheme == ecutsVERLET &&
        nbv->grp[0].kernel_type == nbnxnk8x8x8_CUDA)
    {
        nbnxn_cuda_pme_loadbal_update_param(nbv->cu_nbv, ic);
    }
    else
    {
        init_interaction_const_tables(NULL, ic, bUsesSimpleTables,
                                      rtab);
    }

    if (pme_lb->cutoff_scheme == ecutsVERLET && nbv->ngrp > 1)
    {
        init_interaction_const_tables(NULL, ic, bUsesSimpleTables,
                                      rtab);
    }

    if (cr->duty & DUTY_PME)
    {
        if (pme_lb->setup[pme_lb->cur].pmedata == NULL)
        {
            /* Generate a new PME data structure,
             * copying part of the old pointers.
             */
            gmx_pme_reinit(&set->pmedata,
                           cr, pme_lb->setup[0].pmedata, ir,
                           set->grid);
        }
        *pmedata = set->pmedata;
    }
    else
    {
        /* Tell our PME-only node to switch grid */
        gmx_pme_send_switchgrid(cr, set->grid, set->ewaldcoeff);
    }

    if (debug)
    {
        print_grid(NULL, debug, "", "switched to", set, -1);
    }

    if (pme_lb->stage == pme_lb->nstage)
    {
        print_grid(fp_err, fp_log, "", "optimal", set, -1);
    }

    return TRUE;
}