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

/*
 * Copyright (c) 1999-2008 Mark D. Hill and David A. Wood
 * 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
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/*
 * $Id$
 *
 */

#include "Global.hh"
#include "RubyConfig.hh"
#include "StoreBuffer.hh"
#include "AbstractChip.hh"
#include "System.hh"
#include "Driver.hh"
#include "Vector.hh"
#include "RubyEventQueue.hh"
#include "AddressProfiler.hh"
#include "Sequencer.hh"
#include "SubBlock.hh"
#include "Profiler.hh"

// *** Begin Helper class ***
struct StoreBufferEntry {
  StoreBufferEntry() {} // So we can allocate a vector of StoreBufferEntries
  StoreBufferEntry(const SubBlock& block, CacheRequestType type, const Address& pc, AccessModeType access_mode, int size, int thread) : m_subblock(block) {
    m_type = type;
    m_pc = pc;
    m_access_mode = access_mode;
    m_size = size;
    m_thread = thread;
    m_time = g_eventQueue_ptr->getTime();
  }

  void print(ostream& out) const
  {
    out << "[StoreBufferEntry: "
        << "SubBlock: " << m_subblock
        << ", Type: " << m_type
        << ", PC: " << m_pc
        << ", AccessMode: " << m_access_mode
        << ", Size: " << m_size
        << ", Thread: " << m_thread
        << ", Time: " << m_time
        << "]";
  }

  SubBlock m_subblock;
  CacheRequestType m_type;
  Address m_pc;
  AccessModeType m_access_mode;
  int m_size;
  int m_thread;
  Time m_time;
};

extern inline
ostream& operator<<(ostream& out, const StoreBufferEntry& obj)
{
  obj.print(out);
  out << flush;
  return out;
}

// *** End Helper class ***

const int MAX_ENTRIES = 128;

static void inc_index(int& index)
{
  index++;
  if (index >= MAX_ENTRIES) {
    index = 0;
  }
}

StoreBuffer::StoreBuffer(AbstractChip* chip_ptr, int version) :
  m_store_cache()
{
  m_chip_ptr = chip_ptr;
  m_version = version;
  m_queue_ptr = new Vector<StoreBufferEntry>(MAX_ENTRIES);
  m_queue_ptr->setSize(MAX_ENTRIES);
  m_pending = false;
  m_seen_atomic = false;
  m_head = 0;
  m_tail = 0;
  m_size = 0;
  m_deadlock_check_scheduled = false;
}

StoreBuffer::~StoreBuffer()
{
  delete m_queue_ptr;
}

// Used only to check for deadlock
void StoreBuffer::wakeup()
{
  // Check for deadlock of any of the requests
  Time current_time = g_eventQueue_ptr->getTime();

  int queue_pointer = m_head;
  for (int i=0; i<m_size; i++) {
    if (current_time - (getEntry(queue_pointer).m_time) >= g_DEADLOCK_THRESHOLD) {
      WARN_EXPR(getEntry(queue_pointer));
      WARN_EXPR(m_chip_ptr->getID());
      WARN_EXPR(current_time);
      ERROR_MSG("Possible Deadlock detected");
    }
    inc_index(queue_pointer);
  }

  if (m_size > 0) { // If there are still outstanding requests, keep checking
    g_eventQueue_ptr->scheduleEvent(this, g_DEADLOCK_THRESHOLD);
  } else {
    m_deadlock_check_scheduled = false;
  }
}

void StoreBuffer::printConfig(ostream& out)
{
  out << "Store buffer entries: " << MAX_ENTRIES << " (Only valid if TSO is enabled)" << endl;
}

// Handle an incoming store request, this method is responsible for
// calling hitCallback as needed
void StoreBuffer::insertStore(const CacheMsg& request)
{
  Address addr = request.getAddress();
  CacheRequestType type = request.getType();
  Address pc = request.getProgramCounter();
  AccessModeType access_mode = request.getAccessMode();
  int size = request.getSize();
  int threadID = request.getThreadID();

  DEBUG_MSG(STOREBUFFER_COMP, MedPrio, "insertStore");
  DEBUG_EXPR(STOREBUFFER_COMP, MedPrio, g_eventQueue_ptr->getTime());
  assert((type == CacheRequestType_ST) || (type == CacheRequestType_ATOMIC));
  assert(isReady());

  // See if we should schedule a deadlock check
  if (m_deadlock_check_scheduled == false) {
    g_eventQueue_ptr->scheduleEvent(this, g_DEADLOCK_THRESHOLD);
    m_deadlock_check_scheduled = true;
  }

  // Perform the hit-callback for the store
  SubBlock subblock(addr, size);
  if(type == CacheRequestType_ST) {
    g_system_ptr->getDriver()->hitCallback(m_chip_ptr->getID(), subblock, type, threadID);
    assert(subblock.getSize() != 0);
  } else {
    // wait to perform the hitCallback until later for Atomics
  }

  // Perform possible pre-fetch
  if(!isEmpty()) {
    CacheMsg new_request = request;
    new_request.getPrefetch() = PrefetchBit_Yes;
    m_chip_ptr->getSequencer(m_version)->makeRequest(new_request);
  }

  // Update the StoreCache
  m_store_cache.add(subblock);

  // Enqueue the entry
  StoreBufferEntry entry(subblock, type, pc, access_mode, size, threadID); // FIXME
  enqueue(entry);

  if(type == CacheRequestType_ATOMIC) {
    m_seen_atomic = true;
  }

  processHeadOfQueue();
}

void StoreBuffer::callBack(const Address& addr, DataBlock& data)
{
  DEBUG_MSG(STOREBUFFER_COMP, MedPrio, "callBack");
  DEBUG_EXPR(STOREBUFFER_COMP, MedPrio, g_eventQueue_ptr->getTime());
  assert(!isEmpty());
  assert(m_pending == true);
  assert(line_address(addr) == addr);
  assert(line_address(m_pending_address) == addr);
  assert(line_address(peek().m_subblock.getAddress()) == addr);
  CacheRequestType type = peek().m_type;
  int threadID = peek().m_thread;
  assert((type == CacheRequestType_ST) || (type == CacheRequestType_ATOMIC));
  m_pending = false;

  // If oldest entry was ATOMIC, perform the callback
  if(type == CacheRequestType_ST) {
    // We already performed the call back for the store at insert time
  } else {
    // We waited to perform the hitCallback until now for Atomics
    peek().m_subblock.mergeFrom(data);  // copy the correct bytes from DataBlock into the SubBlock for the Load part of the atomic Load/Store
    g_system_ptr->getDriver()->hitCallback(m_chip_ptr->getID(), peek().m_subblock, type, threadID);
    m_seen_atomic = false;

    /// FIXME - record the time spent in the store buffer - split out ST vs ATOMIC
  }
  assert(peek().m_subblock.getSize() != 0);

  // Apply the head entry to the datablock
  peek().m_subblock.mergeTo(data);  // For both the Store and Atomic cases

  // Update the StoreCache
  m_store_cache.remove(peek().m_subblock);

  // Dequeue the entry from the store buffer
  dequeue();

  if (isEmpty()) {
    assert(m_store_cache.isEmpty());
  }

  if(type == CacheRequestType_ATOMIC) {
    assert(isEmpty());
  }

  // See if we can remove any more entries
  processHeadOfQueue();
}

void StoreBuffer::processHeadOfQueue()
{
  if(!isEmpty() && !m_pending) {
    StoreBufferEntry& entry = peek();
    assert(m_pending == false);
    m_pending = true;
    m_pending_address = entry.m_subblock.getAddress();
    CacheMsg request(entry.m_subblock.getAddress(), entry.m_subblock.getAddress(), entry.m_type, entry.m_pc, entry.m_access_mode, entry.m_size, PrefetchBit_No, 0, Address(0), entry.m_thread);
    m_chip_ptr->getSequencer(m_version)->doRequest(request);
  }
}

bool StoreBuffer::isReady() const
{
  return ((m_size < MAX_ENTRIES) && (!m_seen_atomic));
}

// Queue implementation methods

StoreBufferEntry& StoreBuffer::peek()
{
  return getEntry(m_head);
}

void StoreBuffer::dequeue()
{
  assert(m_size > 0);
  m_size--;
  inc_index(m_head);
}

void StoreBuffer::enqueue(const StoreBufferEntry& entry)
{
  //  assert(isReady());
  (*m_queue_ptr)[m_tail] = entry;
  m_size++;
  g_system_ptr->getProfiler()->storeBuffer(m_size, m_store_cache.size());
  inc_index(m_tail);
}

StoreBufferEntry& StoreBuffer::getEntry(int index)
{
  return (*m_queue_ptr)[index];
}

void StoreBuffer::print(ostream& out) const
{
  out << "[StoreBuffer]";
}