src/mem/qos/policy_pf.hh

/*
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 * property including but not limited to intellectual property relating
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 * this software without specific prior written permission.
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 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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 * Author: Giacomo Travaglini
 */

#ifndef __MEM_QOS_POLICY_PF_HH__
#define __MEM_QOS_POLICY_PF_HH__

#include "mem/qos/policy.hh"
#include "params/QoSPropFairPolicy.hh"

namespace QoS {

/**
 * Proportional Fair QoS Policy
 * Providing a configurable fair scheduling policy based on
 * utilization; utilization is directly proportional to a
 * score which is inversely proportional to the QoS priority
 * Users can tune the policy by adjusting the weight parameter
 * (weight of the formula)
 *
 * This is the formula used by the policy
 * ((1.0 - weight) * old_score) + (weight * served_bytes);
 */
class PropFairPolicy : public Policy
{
    using Params = QoSPropFairPolicyParams;
    const Params *params() const
    { return static_cast<const Params *>(_params); }

  public:
    PropFairPolicy(const Params*);
    virtual ~PropFairPolicy();

    /**
     * Initialize the master's score by providing
     * the master's name and initial score value.
     * The master's name has to match a name in the system.
     *
     * @param master master's name to lookup.
     * @param score initial score value for the master
     */
    void initMasterName(const std::string master, const double score);

    /**
     * Initialize the master's score by providing
     * the master's SimObject pointer and initial score value.
     * The master's pointer has to match a master in the system.
     *
     * @param master master's SimObject pointer to lookup.
     * @param score initial score value for the master
     */
    void initMasterObj(const SimObject* master, const double score);

    /**
     * Schedules a packet based on proportional fair configuration
     *
     * @param m_id master id to schedule
     * @param pkt_size size of the packet
     * @return QoS priority value
     */
    virtual uint8_t
    schedule(const MasterID m_id, const uint64_t pkt_size) override;

  protected:
    template <typename Master>
    void initMaster(const Master master, const double score);

    inline double
    updateScore(const double old_score, const uint64_t served_bytes) const;

  protected:
    /** PF Policy weight */
    const double weight;

    /** history is keeping track of every master's score */
    using MasterHistory = std::pair<MasterID, double>;
    std::vector<MasterHistory> history;
};

} // namespace QoS

#endif // __MEM_QOS_POLICY_PF_HH__