path: root/src/mem/ruby/system/SparseMemory.cc

/*
 * Copyright (c) 2009 Advanced Micro Devices, Inc.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met: redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer;
 * redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution;
 * neither the name of the copyright holders nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "mem/ruby/system/SparseMemory.hh"

SparseMemory::SparseMemory(int number_of_bits, int number_of_levels)
{
    int even_level_bits;
    int extra;
    m_total_number_of_bits = number_of_bits;
    m_number_of_levels = number_of_levels;
    
    //
    // Create the array that describes the bits per level
    //
    m_number_of_bits_per_level = new int[m_number_of_levels];
    even_level_bits = m_total_number_of_bits / m_number_of_levels;
    extra = m_total_number_of_bits % m_number_of_levels;
    for (int level = 0; level < m_number_of_levels; level++) {
        if (level < extra)
            m_number_of_bits_per_level[level] = even_level_bits + 1;
        else
            m_number_of_bits_per_level[level] = even_level_bits;
    }
    m_map_head = new SparseMapType;
    
    m_total_adds = 0;
    m_total_removes = 0;
    m_adds_per_level = new uint64_t[m_number_of_levels];
    m_removes_per_level = new uint64_t[m_number_of_levels];
    for (int level = 0; level < m_number_of_levels; level++) {
        m_adds_per_level[level] = 0;
        m_removes_per_level[level] = 0;
    }
}

SparseMemory::~SparseMemory()
{
    recursivelyRemoveTables(m_map_head, 0);
    delete m_map_head;
    delete [] m_number_of_bits_per_level;
    delete [] m_adds_per_level;
    delete [] m_removes_per_level;
}

// Recursively search table hierarchy for the lowest level table.
// Delete the lowest table first, the tables above
void 
SparseMemory::recursivelyRemoveTables(SparseMapType* curTable, int curLevel)
{
    SparseMapType::iterator iter;

    for (iter = curTable->begin(); iter != curTable->end(); iter++) {
        SparseMemEntry* entryStruct = &((*iter).second);
        
        if (curLevel != (m_number_of_levels - 1)) {
            // If the not at the last level, analyze those lower level
            // tables first, then delete those next tables
            SparseMapType* nextTable = (SparseMapType*)(entryStruct->entry);
            recursivelyRemoveTables(nextTable, (curLevel + 1));
            delete nextTable;
        } else {
            // If at the last level, delete the directory entry
            Directory_Entry* dirEntry;
            dirEntry = (Directory_Entry*)(entryStruct->entry);
            delete dirEntry;
        }
        entryStruct->entry = NULL;
    }  
    
    // Once all entries have been deleted, erase the entries
    curTable->erase(curTable->begin(), curTable->end());
}

// tests to see if an address is present in the memory
bool 
SparseMemory::exist(const Address& address) const
{
    SparseMapType* curTable = m_map_head;
    Address curAddress;
    
    // Initiallize the high bit to be the total number of bits plus
    // the block offset.  However the highest bit index is one less
    // than this value.
    int highBit = m_total_number_of_bits + RubySystem::getBlockSizeBits();
    int lowBit;
    assert(address == line_address(address));
    DEBUG_EXPR(CACHE_COMP, HighPrio, address);
    
    for (int level = 0; level < m_number_of_levels; level++) {
        // Create the appropriate sub address for this level
        // Note: that set Address is inclusive of the specified range,
        // thus the high bit is one less than the total number of bits
        // used to create the address.
        lowBit = highBit - m_number_of_bits_per_level[level];
        curAddress.setAddress(address.bitSelect(lowBit, highBit - 1));
        
        DEBUG_EXPR(CACHE_COMP, HighPrio, level);
        DEBUG_EXPR(CACHE_COMP, HighPrio, lowBit);
        DEBUG_EXPR(CACHE_COMP, HighPrio, highBit - 1);
        DEBUG_EXPR(CACHE_COMP, HighPrio, curAddress);
        
        // Adjust the highBit value for the next level
        highBit -= m_number_of_bits_per_level[level];
        
        // If the address is found, move on to the next level.
        // Otherwise, return not found
        if (curTable->count(curAddress) != 0) {
            curTable = (SparseMapType*)(((*curTable)[curAddress]).entry);
        } else {
            DEBUG_MSG(CACHE_COMP, HighPrio, "Not found");
            return false;
        }
    }
    
    DEBUG_MSG(CACHE_COMP, HighPrio, "Entry found");
    return true;
}

// add an address to memory
void 
SparseMemory::add(const Address& address)
{
    assert(address == line_address(address));
    assert(!exist(address));
    
    m_total_adds++;
    
    Address curAddress;
    SparseMapType* curTable = m_map_head;
    SparseMemEntry* entryStruct = NULL;
    
    // Initiallize the high bit to be the total number of bits plus
    // the block offset.  However the highest bit index is one less
    // than this value.
    int highBit = m_total_number_of_bits + RubySystem::getBlockSizeBits();
    int lowBit;
    void* newEntry = NULL;
    
    for (int level = 0; level < m_number_of_levels; level++) {
        // create the appropriate address for this level
        // Note: that set Address is inclusive of the specified range,
        // thus the high bit is one less than the total number of bits
        // used to create the address.
        lowBit = highBit - m_number_of_bits_per_level[level];
        curAddress.setAddress(address.bitSelect(lowBit, highBit - 1));
        
        // Adjust the highBit value for the next level
        highBit -= m_number_of_bits_per_level[level];
        
        // if the address exists in the cur table, move on.  Otherwise
        // create a new table.
        if (curTable->count(curAddress) != 0) {
            curTable = (SparseMapType*)(((*curTable)[curAddress]).entry);
        } else {           
            m_adds_per_level[level]++;

            // if the last level, add a directory entry.  Otherwise add a map.
            if (level == (m_number_of_levels - 1)) {
                Directory_Entry* tempDirEntry = new Directory_Entry();
                tempDirEntry->getDataBlk().clear();
                newEntry = (void*)tempDirEntry;
            } else {
                SparseMapType* tempMap = new SparseMapType;
                newEntry = (void*)(tempMap);
            }

            // Create the pointer container SparseMemEntry and add it
            // to the table.
            entryStruct = new SparseMemEntry;
            entryStruct->entry = newEntry;
            (*curTable)[curAddress] = *entryStruct;
            
            // Move to the next level of the heirarchy
            curTable = (SparseMapType*)newEntry;
        }
    }
    
    assert(exist(address));
    return;
}

// recursively search table hierarchy for the lowest level table.
// remove the lowest entry and any empty tables above it.
int 
SparseMemory::recursivelyRemoveLevels(const Address& address,
                                      CurNextInfo& curInfo)
{
    Address curAddress;
    CurNextInfo nextInfo;
    SparseMemEntry* entryStruct;
    
    // create the appropriate address for this level
    // Note: that set Address is inclusive of the specified range,
    // thus the high bit is one less than the total number of bits
    // used to create the address.
    curAddress.setAddress(address.bitSelect(curInfo.lowBit, 
                                            curInfo.highBit - 1));
    
    DEBUG_EXPR(CACHE_COMP, HighPrio, address);
    DEBUG_EXPR(CACHE_COMP, HighPrio, curInfo.level);
    DEBUG_EXPR(CACHE_COMP, HighPrio, curInfo.lowBit);
    DEBUG_EXPR(CACHE_COMP, HighPrio, curInfo.highBit - 1);
    DEBUG_EXPR(CACHE_COMP, HighPrio, curAddress);
    
    assert(curInfo.curTable->count(curAddress) != 0);
    
    entryStruct = &((*(curInfo.curTable))[curAddress]);
    
    if (curInfo.level < (m_number_of_levels - 1)) {
        // set up next level's info
        nextInfo.curTable = (SparseMapType*)(entryStruct->entry);
        nextInfo.level = curInfo.level + 1;

        nextInfo.highBit = curInfo.highBit - 
            m_number_of_bits_per_level[curInfo.level];

        nextInfo.lowBit = curInfo.lowBit - 
            m_number_of_bits_per_level[curInfo.level + 1];
        
        // recursively search the table hierarchy
        int tableSize = recursivelyRemoveLevels(address, nextInfo);
        
        // If this table below is now empty, we must delete it and
        // erase it from our table.
        if (tableSize == 0) {
            m_removes_per_level[curInfo.level]++;
            delete nextInfo.curTable;
            entryStruct->entry = NULL;
            curInfo.curTable->erase(curAddress);
        }
    } else {
        // if this is the last level, we have reached the Directory
        // Entry and thus we should delete it including the
        // SparseMemEntry container struct.
        Directory_Entry* dirEntry;
        dirEntry = (Directory_Entry*)(entryStruct->entry);
        entryStruct->entry = NULL;
        delete dirEntry;
        curInfo.curTable->erase(curAddress);
        m_removes_per_level[curInfo.level]++;
    }
    return curInfo.curTable->size();
}

// remove an entry from the table
void 
SparseMemory::remove(const Address& address)
{
    assert(address == line_address(address));
    assert(exist(address));
    
    m_total_removes++;
    
    CurNextInfo nextInfo;
    
    // Initialize table pointer and level value
    nextInfo.curTable = m_map_head;
    nextInfo.level = 0;
    
    // Initiallize the high bit to be the total number of bits plus
    // the block offset.  However the highest bit index is one less
    // than this value.
    nextInfo.highBit = m_total_number_of_bits + RubySystem::getBlockSizeBits();
    nextInfo.lowBit = nextInfo.highBit - m_number_of_bits_per_level[0];;
    
    // recursively search the table hierarchy for empty tables
    // starting from the level 0.  Note we do not check the return
    // value because the head table is never deleted;
    recursivelyRemoveLevels(address, nextInfo);
    
    assert(!exist(address));
    return;
}

// looks an address up in memory
Directory_Entry* 
SparseMemory::lookup(const Address& address)
{
    assert(exist(address));
    assert(address == line_address(address));

    DEBUG_EXPR(CACHE_COMP, HighPrio, address);
    
    Address curAddress;
    SparseMapType* curTable = m_map_head;
    Directory_Entry* entry = NULL;
    
    // Initiallize the high bit to be the total number of bits plus
    // the block offset.  However the highest bit index is one less
    // than this value.
    int highBit = m_total_number_of_bits + RubySystem::getBlockSizeBits();
    int lowBit;
    
    for (int level = 0; level < m_number_of_levels; level++) {
        // create the appropriate address for this level
        // Note: that set Address is inclusive of the specified range,
        // thus the high bit is one less than the total number of bits
        // used to create the address.
        lowBit = highBit - m_number_of_bits_per_level[level];
        curAddress.setAddress(address.bitSelect(lowBit, highBit - 1));
        
        DEBUG_EXPR(CACHE_COMP, HighPrio, level);
        DEBUG_EXPR(CACHE_COMP, HighPrio, lowBit);
        DEBUG_EXPR(CACHE_COMP, HighPrio, highBit - 1);
        DEBUG_EXPR(CACHE_COMP, HighPrio, curAddress);
        
        // Adjust the highBit value for the next level
        highBit -= m_number_of_bits_per_level[level];
        
        // The entry should be in the table and valid
        curTable = (SparseMapType*)(((*curTable)[curAddress]).entry);
        assert(curTable != NULL);
    }
    
    // The last entry actually points to the Directory entry not a table
    entry = (Directory_Entry*)curTable;

    return entry;
}

void 
SparseMemory::print(ostream& out) const
{
}

void 
SparseMemory::printStats(ostream& out) const
{
    out << "total_adds: " << m_total_adds << " [";
    for (int level = 0; level < m_number_of_levels; level++) {
        out << m_adds_per_level[level] << " ";
    }
    out << "]" << endl;
    out << "total_removes: " << m_total_removes << " [";
    for (int level = 0; level < m_number_of_levels; level++) {
        out << m_removes_per_level[level] << " ";
    }
    out << "]" << endl;
}