gem5/src/mem/ruby/system/TimerTable.cc
Nilay Vaish 39e9445468 ruby: consumer: avoid using receiver side clock
A set of patches was recently committed to allow multiple clock domains
in ruby. In those patches, I had inadvertently made an incorrect use of
the clocks. Suppose object A needs to schedule an event on object B. It
was possible that A accesses B's clock to schedule the event. This is not
possible in actual system. Hence, changes are being to the Consumer class
so as to avoid such happenings. Note that in a multi eventq simulation,
this can possibly lead to an incorrect simulation.

There are two functions in the Consumer class that are used for scheduling
events. The first function takes in the relative delay over the current time
as the argument and adds the current time to it for scheduling the event.
The second function takes in the absolute time (in ticks) for scheduling the
event. The first function is now being moved to protected section of the
class so that only objects of the derived classes can use it. All other
objects will have to specify absolute time while scheduling an event
for some consumer.
2013-03-22 15:53:26 -05:00

129 lines
3.6 KiB
C++

/*
* 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.
*/
#include "mem/ruby/common/Global.hh"
#include "mem/ruby/system/System.hh"
#include "mem/ruby/system/TimerTable.hh"
TimerTable::TimerTable()
: m_next_time(0)
{
m_consumer_ptr = NULL;
m_clockobj_ptr = NULL;
m_next_valid = false;
m_next_address = Address(0);
}
bool
TimerTable::isReady() const
{
if (m_map.empty())
return false;
if (!m_next_valid) {
updateNext();
}
assert(m_next_valid);
return (m_clockobj_ptr->curCycle() >= m_next_time);
}
const Address&
TimerTable::readyAddress() const
{
assert(isReady());
if (!m_next_valid) {
updateNext();
}
assert(m_next_valid);
return m_next_address;
}
void
TimerTable::set(const Address& address, Cycles relative_latency)
{
assert(address == line_address(address));
assert(relative_latency > 0);
assert(!m_map.count(address));
Cycles ready_time = m_clockobj_ptr->curCycle() + relative_latency;
m_map[address] = ready_time;
assert(m_consumer_ptr != NULL);
m_consumer_ptr->
scheduleEventAbsolute(m_clockobj_ptr->clockPeriod() * ready_time);
m_next_valid = false;
// Don't always recalculate the next ready address
if (ready_time <= m_next_time) {
m_next_valid = false;
}
}
void
TimerTable::unset(const Address& address)
{
assert(address == line_address(address));
assert(m_map.count(address));
m_map.erase(address);
// Don't always recalculate the next ready address
if (address == m_next_address) {
m_next_valid = false;
}
}
void
TimerTable::print(std::ostream& out) const
{
}
void
TimerTable::updateNext() const
{
if (m_map.empty()) {
assert(!m_next_valid);
return;
}
AddressMap::const_iterator i = m_map.begin();
AddressMap::const_iterator end = m_map.end();
m_next_address = i->first;
m_next_time = i->second;
++i;
for (; i != end; ++i) {
if (i->second < m_next_time) {
m_next_address = i->first;
m_next_time = i->second;
}
}
m_next_valid = true;
}