Function chooseWhetherToMultithreadQureg

quest/src/core/autodeployer.cpp:109–121

void chooseWhetherToMultithreadQureg(int numQubits, int isDensMatr, int &useMultithread, int numQuregNodes) {

    // if the flag is already set (user-given, or inferred from env), don't change it
    if (useMultithread != modeflag::USE_AUTO)
        return;

    // otherwise, choose to multithread based on Qureg size
    int effectiveNumQubits = mem_getEffectiveNumStateVecQubitsPerNode(numQubits, isDensMatr, numQuregNodes);
    useMultithread = (effectiveNumQubits >= MIN_NUM_LOCAL_QUBITS_FOR_AUTO_QUREG_MULTITHREADING);

    // note the qureg may be simultaneously GPU-accelerated and so never use its
    // multithreaded CPU routines, except in functions which accept multiple Quregs
}


void autodep_chooseQuregDeployment(int numQubits, int isDensMatr, int &useDistrib, int &useGpuAccel, int &useMultithread, QuESTEnv env) {