sat_counter.hh

来自「M5,一个功能强大的多处理器系统模拟器.很多针对处理器架构,性能的研究都使用它作」· HH 代码 · 共 194 行

/*
 * Copyright (c) 2001, 2002, 2003, 2004, 2005
 * The Regents of The University of Michigan
 * All Rights Reserved
 *
 * This code is part of the M5 simulator.
 *
 * Permission is granted to use, copy, create derivative works and
 * redistribute this software and such derivative works for any
 * purpose, so long as the copyright notice above, this grant of
 * permission, and the disclaimer below appear in all copies made; and
 * so long as the name of The University of Michigan is not used in
 * any advertising or publicity pertaining to the use or distribution
 * of this software without specific, written prior authorization.
 *
 * THIS SOFTWARE IS PROVIDED AS IS, WITHOUT REPRESENTATION FROM THE
 * UNIVERSITY OF MICHIGAN AS TO ITS FITNESS FOR ANY PURPOSE, AND
 * WITHOUT WARRANTY BY THE UNIVERSITY OF MICHIGAN OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE. THE REGENTS OF THE UNIVERSITY OF MICHIGAN SHALL NOT BE
 * LIABLE FOR ANY DAMAGES, INCLUDING DIRECT, SPECIAL, INDIRECT,
 * INCIDENTAL, OR CONSEQUENTIAL DAMAGES, WITH RESPECT TO ANY CLAIM
 * ARISING OUT OF OR IN CONNECTION WITH THE USE OF THE SOFTWARE, EVEN
 * IF IT HAS BEEN OR IS HEREAFTER ADVISED OF THE POSSIBILITY OF SUCH
 * DAMAGES.
 *
 * Authors: Steven E. Raasch
 *          Steven K. Reinhardt
 */

#ifndef __SAT_COUNTER_HH__
#define __SAT_COUNTER_HH__

#include <string>

#include "base/predictor.hh"

#include "base/statistics.hh"
#include "sim/stats.hh"

//
//
//  A simple saturating counter predictor
//
//
class SaturatingCounterPred : public GenericPredictor
{
  private:
    std::string   pred_name;
    std::string   zero_name;
    std::string   one_name;

    unsigned index_bits;
    unsigned counter_bits;
    unsigned zero_change;
    unsigned one_change;
    unsigned thresh;
    unsigned init_value;

    unsigned max_value;       // maximum counter value

    unsigned long max_index;  // also the index mask value
    unsigned *table;

    //  Statistics
    Stats::Scalar<> predicted_one;      // Total predictions of one, preds_one
    Stats::Scalar<> predicted_zero;     // Total predictions of zero, preds_zero
    Stats::Scalar<> correct_pred_one;   // Total correct predictions of one, correct_one
    Stats::Scalar<> correct_pred_zero;  // Total correct predictions of zero, correct_zero

    Stats::Scalar<> record_zero;        //updates_zero
    Stats::Scalar<> record_one;         //updates_one

    Stats::Formula preds_total;
    Stats::Formula pred_frac_zero;
    Stats::Formula pred_frac_one;
    Stats::Formula correct_total;
    Stats::Formula updates_total;
    Stats::Formula pred_rate;
    Stats::Formula frac_correct_zero;
    Stats::Formula frac_correct_one;
    Stats::Formula coverage_zero;
    Stats::Formula coverage_one;

  private:
    bool pred_one(unsigned &counter)  { return counter >  thresh; }
    bool pred_zero(unsigned &counter) { return counter <= thresh; }

    void update_one(unsigned &counter) {

        if (one_change)
            counter += one_change;
        else
            counter = 0;

        // check for wrap
        if (counter > max_value)
            counter = max_value;
    }

    void update_zero(unsigned &counter) {
        if (zero_change) {
            // check for wrap
            if (counter < zero_change)
                counter = 0;
            else
                counter -= zero_change;
        } else
            counter = 0;
    }


  public:

    SaturatingCounterPred(std::string p_name,
                          std::string z_name, std::string o_name,
                          unsigned _index_bits, unsigned _counter_bits = 2,
                          unsigned _zero_change = 1, unsigned _one_change = 1,
                          unsigned _thresh = 1, unsigned _init_value = 0);

    void clear() {
        for (int i = 0; i <= max_index; ++i)
            table[i] = init_value;
    }

    //  Record the ACTUAL result... and indicate whether the prediction
    //  corresponding to this event was correct
    void record(unsigned long _index, unsigned _val, unsigned _predicted,
                unsigned _pdata)
    {
        record(_index, _val, _predicted);
    }

    void record(unsigned long _index, unsigned _val, unsigned _predicted) {
        unsigned long index = _index & max_index;

        if (_val) {
            update_one(table[index]);
            ++record_one;

            if (_predicted)
                ++correct_pred_one;
        } else {
            update_zero(table[index]);
            ++record_zero;

            if (!_predicted)
                ++correct_pred_zero;
        }
    }

    unsigned value(unsigned long _index) {
        unsigned long index = _index & max_index;

        return table[index];
    }


    unsigned predict(unsigned long _index, unsigned &pdata) {
        return predict(_index);
    }

    unsigned predict(unsigned long _index) {
        unsigned long index = _index & max_index;

        if (pred_one(table[index])) {
            ++predicted_one;
            return 1;
        }

        ++predicted_zero;
        return 0;
    }

    //  No internal state is changed here
    unsigned peek(unsigned long _index) {
        unsigned long index = _index & max_index;

        if (pred_one(table[index]))
            return 1;

        return 0;
    }


    //=======================================================
    void regStats();
    void regFormulas();
};


#endif // __SAT_COUNTER_HH__