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/*! \internal \file
 * \brief
 * Defines routine for building simulation workload task description.
 *
 * \author Paul Bauer <paul.bauer.q@gmail.com>
 * \ingroup module_taskassignment
 */
#include "gmxpre.h"

#include "gromacs/taskassignment/decidesimulationworkload.h"

#include "gromacs/ewald/pme.h"
#include "gromacs/mdtypes/multipletimestepping.h"
#include "gromacs/taskassignment/decidegpuusage.h"
#include "gromacs/taskassignment/taskassignment.h"
#include "gromacs/utility/arrayref.h"

namespace gmx
{

SimulationWorkload createSimulationWorkload(const t_inputrec& inputrec,
                                            const bool        disableNonbondedCalculation,
                                            const DevelopmentFeatureFlags& devFlags,
                                            bool       havePpDomainDecomposition,
                                            bool       haveSeparatePmeRank,
                                            bool       useGpuForNonbonded,
                                            PmeRunMode pmeRunMode,
                                            bool       useGpuForBonded,
                                            bool       useGpuForUpdate,
                                            bool       useGpuDirectHalo,
                                            bool       canUseDirectGpuComm,
                                            bool       useGpuPmeDecomposition)
{
    SimulationWorkload simulationWorkload;
    simulationWorkload.computeNonbonded = !disableNonbondedCalculation;
    simulationWorkload.computeNonbondedAtMtsLevel1 =
            simulationWorkload.computeNonbonded && inputrec.useMts
            && inputrec.mtsLevels.back().forceGroups[static_cast<int>(MtsForceGroups::Nonbonded)];
    simulationWorkload.computeMuTot    = inputrecNeedMutot(&inputrec);
    simulationWorkload.useCpuNonbonded = !useGpuForNonbonded;
    simulationWorkload.useGpuNonbonded = useGpuForNonbonded;
    simulationWorkload.useCpuPme       = (pmeRunMode == PmeRunMode::CPU);
    simulationWorkload.useGpuPme = (pmeRunMode == PmeRunMode::GPU || pmeRunMode == PmeRunMode::Mixed);
    simulationWorkload.useGpuPmeFft              = (pmeRunMode == PmeRunMode::GPU);
    simulationWorkload.useGpuBonded              = useGpuForBonded;
    simulationWorkload.useGpuUpdate              = useGpuForUpdate;
    simulationWorkload.havePpDomainDecomposition = havePpDomainDecomposition;
    simulationWorkload.useCpuHaloExchange        = havePpDomainDecomposition && !useGpuDirectHalo;
    simulationWorkload.useGpuHaloExchange        = useGpuDirectHalo;
    if (pmeRunMode == PmeRunMode::None)
    {
        GMX_RELEASE_ASSERT(!haveSeparatePmeRank, "Can not have separate PME rank(s) without PME.");
    }
    simulationWorkload.haveSeparatePmeRank = haveSeparatePmeRank;
    simulationWorkload.useGpuPmePpCommunication =
            haveSeparatePmeRank && canUseDirectGpuComm
            && (pmeRunMode == PmeRunMode::GPU || pmeRunMode == PmeRunMode::Mixed);
    simulationWorkload.useCpuPmePpCommunication =
            haveSeparatePmeRank && !simulationWorkload.useGpuPmePpCommunication;
    GMX_RELEASE_ASSERT(!(simulationWorkload.useGpuPmePpCommunication
                         && simulationWorkload.useCpuPmePpCommunication),
                       "Cannot do PME-PP communication on both CPU and GPU");
    simulationWorkload.useGpuDirectCommunication =
            simulationWorkload.useGpuHaloExchange || simulationWorkload.useGpuPmePpCommunication;
    simulationWorkload.useGpuPmeDecomposition       = useGpuPmeDecomposition;
    simulationWorkload.haveEwaldSurfaceContribution = haveEwaldSurfaceContribution(inputrec);
    simulationWorkload.useMts                       = inputrec.useMts;
    const bool featuresRequireGpuBufferOps = useGpuForUpdate || simulationWorkload.useGpuDirectCommunication;
    simulationWorkload.useGpuXBufferOps =
            (devFlags.enableGpuBufferOps || featuresRequireGpuBufferOps) && !inputrec.useMts;
    simulationWorkload.useGpuFBufferOps =
            (devFlags.enableGpuBufferOps || featuresRequireGpuBufferOps) && !inputrec.useMts;
    if (simulationWorkload.useGpuXBufferOps || simulationWorkload.useGpuFBufferOps)
    {
        GMX_ASSERT(simulationWorkload.useGpuNonbonded,
                   "Can only offload X/F buffer ops if nonbonded computation is also offloaded");
    }
    simulationWorkload.useMdGpuGraph =
            devFlags.enableCudaGraphs && useGpuForUpdate
            && (simulationWorkload.haveSeparatePmeRank ? simulationWorkload.useGpuPmePpCommunication : true)
            && (havePpDomainDecomposition ? simulationWorkload.useGpuHaloExchange : true)
            && (havePpDomainDecomposition ? (GMX_THREAD_MPI > 0) : true);
    return simulationWorkload;
}

} // namespace gmx
