policy_pf.cc

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 * Author: Giacomo Travaglini
 */
 
#include "mem/qos/policy_pf.hh"
 
#include "mem/request.hh"
 
namespace QoS {
 
PropFairPolicy::PropFairPolicy(const Params* p)
  : Policy(p), weight(p->weight)
{
    fatal_if(weight < 0 || weight > 1,
        "weight must be a value between 0 and 1");
}
 
PropFairPolicy::~PropFairPolicy()
{}
 
template <typename Requestor>
void
PropFairPolicy::initRequestor(const Requestor requestor, const double score)
{
    RequestorID id = memCtrl->system()->lookupRequestorId(requestor);
 
    assert(id != Request::invldRequestorId);
 
    // Setting the Initial score for the selected requestor.
    history.push_back(std::make_pair(id, score));
 
    fatal_if(history.size() > memCtrl->numPriorities(),
        "Policy's maximum number of requestors is currently dictated "
        "by the maximum number of priorities\n");
}
 
void
PropFairPolicy::initRequestorName(const std::string requestor, const double score)
{
    initRequestor(requestor, score);
}
 
void
PropFairPolicy::initRequestorObj(const SimObject* requestor, const double score)
{
    initRequestor(requestor, score);
}
 
double
PropFairPolicy::updateScore(
    const double old_score, const uint64_t served_bytes) const
{
    return ((1.0 - weight) * old_score) + (weight * served_bytes);
}
 
uint8_t
PropFairPolicy::schedule(const RequestorID pkt_id, const uint64_t pkt_size)
{
    auto sort_pred =
    [] (const RequestorHistory& lhs, const RequestorHistory& rhs)
    { return lhs.second > rhs.second; };
 
    // Sorting in reverse in base of personal history:
    // First elements have higher history/score -> lower priority.
    // The qos priority is the position in the sorted vector.
    std::sort(history.begin(), history.end(), sort_pred);
 
    const double served_bytes = static_cast<double>(pkt_size);
 
    uint8_t pkt_priority = 0;
    for (auto m_hist = history.begin(); m_hist != history.end(); m_hist++) {
 
        RequestorID curr_id = m_hist->first;
        double& curr_score = m_hist->second;
 
        if (curr_id == pkt_id) {
            // The qos priority is the position in the sorted vector.
            pkt_priority = std::distance(history.begin(), m_hist);
 
            curr_score = updateScore(curr_score, served_bytes);
        } else {
            curr_score = updateScore(curr_score, 0);
        }
    }
 
    return pkt_priority;
}
 
} // namespace QoS
 
QoS::PropFairPolicy *
QoSPropFairPolicyParams::create()
{
    return new QoS::PropFairPolicy(this);
}