gem5/src/mem/bus.cc
Nathan Binkert abc76f20cb Major changes to how SimObjects are created and initialized. Almost all
creation and initialization now happens in python.  Parameter objects
are generated and initialized by python.  The .ini file is now solely for
debugging purposes and is not used in construction of the objects in any
way.

--HG--
extra : convert_revision : 7e722873e417cb3d696f2e34c35ff488b7bff4ed
2007-07-23 21:51:38 -07:00

620 lines
19 KiB
C++

/*
* Copyright (c) 2006 The Regents of The University of Michigan
* 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.
*
* Authors: Ali Saidi
*/
/**
* @file
* Definition of a bus object.
*/
#include <limits>
#include "base/misc.hh"
#include "base/trace.hh"
#include "mem/bus.hh"
#include "params/Bus.hh"
Port *
Bus::getPort(const std::string &if_name, int idx)
{
if (if_name == "default") {
if (defaultPort == NULL) {
defaultPort = new BusPort(csprintf("%s-default",name()), this,
defaultId);
cachedBlockSizeValid = false;
return defaultPort;
} else
fatal("Default port already set\n");
}
int id;
if (if_name == "functional") {
if (!funcPort) {
id = maxId++;
funcPort = new BusPort(csprintf("%s-p%d-func", name(), id), this, id);
funcPortId = id;
interfaces[id] = funcPort;
}
return funcPort;
}
// if_name ignored? forced to be empty?
id = maxId++;
assert(maxId < std::numeric_limits<typeof(maxId)>::max());
BusPort *bp = new BusPort(csprintf("%s-p%d", name(), id), this, id);
interfaces[id] = bp;
cachedBlockSizeValid = false;
return bp;
}
void
Bus::deletePortRefs(Port *p)
{
BusPort *bp = dynamic_cast<BusPort*>(p);
if (bp == NULL)
panic("Couldn't convert Port* to BusPort*\n");
// If this is our one functional port
if (funcPort == bp)
return;
interfaces.erase(bp->getId());
delete bp;
}
/** Get the ranges of anyone other buses that we are connected to. */
void
Bus::init()
{
m5::hash_map<short,BusPort*>::iterator intIter;
for (intIter = interfaces.begin(); intIter != interfaces.end(); intIter++)
intIter->second->sendStatusChange(Port::RangeChange);
}
Bus::BusFreeEvent::BusFreeEvent(Bus *_bus) : Event(&mainEventQueue), bus(_bus)
{}
void Bus::BusFreeEvent::process()
{
bus->recvRetry(-1);
}
const char * Bus::BusFreeEvent::description()
{
return "bus became available";
}
void Bus::occupyBus(PacketPtr pkt)
{
//Bring tickNextIdle up to the present tick
//There is some potential ambiguity where a cycle starts, which might make
//a difference when devices are acting right around a cycle boundary. Using
//a < allows things which happen exactly on a cycle boundary to take up
//only the following cycle. Anything that happens later will have to "wait"
//for the end of that cycle, and then start using the bus after that.
if (tickNextIdle < curTick) {
tickNextIdle = curTick;
if (tickNextIdle % clock != 0)
tickNextIdle = curTick - (curTick % clock) + clock;
}
// The packet will be sent. Figure out how long it occupies the bus, and
// how much of that time is for the first "word", aka bus width.
int numCycles = 0;
// Requests need one cycle to send an address
if (pkt->isRequest())
numCycles++;
else if (pkt->isResponse() || pkt->hasData()) {
// If a packet has data, it needs ceil(size/width) cycles to send it
// We're using the "adding instead of dividing" trick again here
if (pkt->hasData()) {
int dataSize = pkt->getSize();
numCycles += dataSize/width;
if (dataSize % width)
numCycles++;
} else {
// If the packet didn't have data, it must have been a response.
// Those use the bus for one cycle to send their data.
numCycles++;
}
}
// The first word will be delivered after the current tick, the delivery
// of the address if any, and one bus cycle to deliver the data
pkt->firstWordTime =
tickNextIdle +
pkt->isRequest() ? clock : 0 +
clock;
//Advance it numCycles bus cycles.
//XXX Should this use the repeated addition trick as well?
tickNextIdle += (numCycles * clock);
if (!busIdle.scheduled()) {
busIdle.schedule(tickNextIdle);
} else {
busIdle.reschedule(tickNextIdle);
}
DPRINTF(Bus, "The bus is now occupied from tick %d to %d\n",
curTick, tickNextIdle);
// The bus will become idle once the current packet is delivered.
pkt->finishTime = tickNextIdle;
}
/** Function called by the port when the bus is receiving a Timing
* transaction.*/
bool
Bus::recvTiming(PacketPtr pkt)
{
Port *port;
DPRINTF(Bus, "recvTiming: packet src %d dest %d addr 0x%x cmd %s\n",
pkt->getSrc(), pkt->getDest(), pkt->getAddr(), pkt->cmdString());
BusPort *pktPort;
if (pkt->getSrc() == defaultId)
pktPort = defaultPort;
else pktPort = interfaces[pkt->getSrc()];
// If the bus is busy, or other devices are in line ahead of the current
// one, put this device on the retry list.
if (tickNextIdle > curTick ||
(retryList.size() && (!inRetry || pktPort != retryList.front()))) {
addToRetryList(pktPort);
DPRINTF(Bus, "recvTiming: Bus is busy, returning false\n");
return false;
}
short dest = pkt->getDest();
// Make sure to clear the snoop commit flag so it doesn't think an
// access has been handled twice.
if (dest == Packet::Broadcast) {
port = findPort(pkt->getAddr(), pkt->getSrc());
pkt->flags &= ~SNOOP_COMMIT;
if (timingSnoop(pkt, port ? port : interfaces[pkt->getSrc()])) {
bool success;
pkt->flags |= SNOOP_COMMIT;
success = timingSnoop(pkt, port ? port : interfaces[pkt->getSrc()]);
assert(success);
if (pkt->flags & SATISFIED) {
//Cache-Cache transfer occuring
if (inRetry) {
retryList.front()->onRetryList(false);
retryList.pop_front();
inRetry = false;
}
occupyBus(pkt);
DPRINTF(Bus, "recvTiming: Packet sucessfully sent\n");
return true;
}
} else {
//Snoop didn't succeed
DPRINTF(Bus, "Adding1 a retry to RETRY list %d\n",
pktPort->getId());
addToRetryList(pktPort);
return false;
}
} else {
assert(dest >= 0 && dest < maxId);
assert(dest != pkt->getSrc()); // catch infinite loops
port = interfaces[dest];
}
occupyBus(pkt);
if (port) {
if (port->sendTiming(pkt)) {
// Packet was successfully sent. Return true.
// Also take care of retries
if (inRetry) {
DPRINTF(Bus, "Remove retry from list %d\n",
retryList.front()->getId());
retryList.front()->onRetryList(false);
retryList.pop_front();
inRetry = false;
}
return true;
}
// Packet not successfully sent. Leave or put it on the retry list.
DPRINTF(Bus, "Adding2 a retry to RETRY list %d\n",
pktPort->getId());
addToRetryList(pktPort);
return false;
}
else {
//Forwarding up from responder, just return true;
DPRINTF(Bus, "recvTiming: can we be here?\n");
return true;
}
}
void
Bus::recvRetry(int id)
{
// If there's anything waiting, and the bus isn't busy...
if (retryList.size() && curTick >= tickNextIdle) {
//retryingPort = retryList.front();
inRetry = true;
DPRINTF(Bus, "Sending a retry to %s\n", retryList.front()->getPeer()->name());
retryList.front()->sendRetry();
// If inRetry is still true, sendTiming wasn't called
if (inRetry)
{
retryList.front()->onRetryList(false);
retryList.pop_front();
inRetry = false;
//Bring tickNextIdle up to the present
while (tickNextIdle < curTick)
tickNextIdle += clock;
//Burn a cycle for the missed grant.
tickNextIdle += clock;
busIdle.reschedule(tickNextIdle, true);
}
}
//If we weren't able to drain before, we might be able to now.
if (drainEvent && retryList.size() == 0 && curTick >= tickNextIdle) {
drainEvent->process();
// Clear the drain event once we're done with it.
drainEvent = NULL;
}
}
Port *
Bus::findPort(Addr addr, int id)
{
/* An interval tree would be a better way to do this. --ali. */
int dest_id = -1;
PortIter i = portMap.find(RangeSize(addr,1));
if (i != portMap.end())
dest_id = i->second;
// Check if this matches the default range
if (dest_id == -1) {
for (AddrRangeIter iter = defaultRange.begin();
iter != defaultRange.end(); iter++) {
if (*iter == addr) {
DPRINTF(Bus, " found addr %#llx on default\n", addr);
return defaultPort;
}
}
if (responderSet) {
panic("Unable to find destination for addr (user set default "
"responder): %#llx", addr);
} else {
DPRINTF(Bus, "Unable to find destination for addr: %#llx, will use "
"default port", addr);
return defaultPort;
}
}
// we shouldn't be sending this back to where it came from
// do the snoop access and then we should terminate
// the cyclical call.
if (dest_id == id)
return 0;
return interfaces[dest_id];
}
Tick
Bus::atomicSnoop(PacketPtr pkt, Port *responder)
{
Tick response_time = 0;
for (SnoopIter s_iter = snoopPorts.begin();
s_iter != snoopPorts.end();
s_iter++) {
BusPort *p = *s_iter;
if (p != responder && p->getId() != pkt->getSrc()) {
Tick response = p->sendAtomic(pkt);
if (response) {
assert(!response_time); //Multiple responders
response_time = response;
}
}
}
return response_time;
}
void
Bus::functionalSnoop(PacketPtr pkt, Port *responder)
{
// The packet may be changed by another bus on snoops, restore the
// id after each
int src_id = pkt->getSrc();
for (SnoopIter s_iter = snoopPorts.begin();
s_iter != snoopPorts.end();
s_iter++) {
BusPort *p = *s_iter;
if (p != responder && p->getId() != src_id) {
p->sendFunctional(pkt);
}
if (pkt->result == Packet::Success) {
break;
}
pkt->setSrc(src_id);
}
}
bool
Bus::timingSnoop(PacketPtr pkt, Port* responder)
{
for (SnoopIter s_iter = snoopPorts.begin();
s_iter != snoopPorts.end();
s_iter++) {
BusPort *p = *s_iter;
if (p != responder && p->getId() != pkt->getSrc()) {
bool success = p->sendTiming(pkt);
if (!success)
return false;
}
}
return true;
}
/** Function called by the port when the bus is receiving a Atomic
* transaction.*/
Tick
Bus::recvAtomic(PacketPtr pkt)
{
DPRINTF(Bus, "recvAtomic: packet src %d dest %d addr 0x%x cmd %s\n",
pkt->getSrc(), pkt->getDest(), pkt->getAddr(), pkt->cmdString());
assert(pkt->getDest() == Packet::Broadcast);
pkt->flags |= SNOOP_COMMIT;
// Assume one bus cycle in order to get through. This may have
// some clock skew issues yet again...
pkt->finishTime = curTick + clock;
Port *port = findPort(pkt->getAddr(), pkt->getSrc());
Tick snoopTime = atomicSnoop(pkt, port ? port : interfaces[pkt->getSrc()]);
if (snoopTime)
return snoopTime; //Snoop satisfies it
else if (port)
return port->sendAtomic(pkt);
else
return 0;
}
/** Function called by the port when the bus is receiving a Functional
* transaction.*/
void
Bus::recvFunctional(PacketPtr pkt)
{
DPRINTF(Bus, "recvFunctional: packet src %d dest %d addr 0x%x cmd %s\n",
pkt->getSrc(), pkt->getDest(), pkt->getAddr(), pkt->cmdString());
assert(pkt->getDest() == Packet::Broadcast);
pkt->flags |= SNOOP_COMMIT;
Port* port = findPort(pkt->getAddr(), pkt->getSrc());
functionalSnoop(pkt, port ? port : interfaces[pkt->getSrc()]);
// If the snooping found what we were looking for, we're done.
if (pkt->result != Packet::Success && port) {
port->sendFunctional(pkt);
}
}
/** Function called by the port when the bus is receiving a status change.*/
void
Bus::recvStatusChange(Port::Status status, int id)
{
AddrRangeList ranges;
bool snoops;
AddrRangeIter iter;
assert(status == Port::RangeChange &&
"The other statuses need to be implemented.");
DPRINTF(BusAddrRanges, "received RangeChange from device id %d\n", id);
if (id == defaultId) {
defaultRange.clear();
// Only try to update these ranges if the user set a default responder.
if (responderSet) {
defaultPort->getPeerAddressRanges(ranges, snoops);
assert(snoops == false);
for(iter = ranges.begin(); iter != ranges.end(); iter++) {
defaultRange.push_back(*iter);
DPRINTF(BusAddrRanges, "Adding range %#llx - %#llx for default range\n",
iter->start, iter->end);
}
}
} else {
assert((id < maxId && id >= 0) || id == defaultId);
BusPort *port = interfaces[id];
// Clean out any previously existent ids
for (PortIter portIter = portMap.begin();
portIter != portMap.end(); ) {
if (portIter->second == id)
portMap.erase(portIter++);
else
portIter++;
}
for (SnoopIter s_iter = snoopPorts.begin();
s_iter != snoopPorts.end(); ) {
if ((*s_iter)->getId() == id)
s_iter = snoopPorts.erase(s_iter);
else
s_iter++;
}
port->getPeerAddressRanges(ranges, snoops);
if (snoops) {
DPRINTF(BusAddrRanges, "Adding id %d to snoop list\n", id);
snoopPorts.push_back(port);
}
for (iter = ranges.begin(); iter != ranges.end(); iter++) {
DPRINTF(BusAddrRanges, "Adding range %#llx - %#llx for id %d\n",
iter->start, iter->end, id);
if (portMap.insert(*iter, id) == portMap.end())
panic("Two devices with same range\n");
}
}
DPRINTF(MMU, "port list has %d entries\n", portMap.size());
// tell all our peers that our address range has changed.
// Don't tell the device that caused this change, it already knows
m5::hash_map<short,BusPort*>::iterator intIter;
for (intIter = interfaces.begin(); intIter != interfaces.end(); intIter++)
if (intIter->first != id && intIter->first != funcPortId)
intIter->second->sendStatusChange(Port::RangeChange);
if (id != defaultId && defaultPort)
defaultPort->sendStatusChange(Port::RangeChange);
}
void
Bus::addressRanges(AddrRangeList &resp, bool &snoop, int id)
{
resp.clear();
snoop = false;
DPRINTF(BusAddrRanges, "received address range request, returning:\n");
for (AddrRangeIter dflt_iter = defaultRange.begin();
dflt_iter != defaultRange.end(); dflt_iter++) {
resp.push_back(*dflt_iter);
DPRINTF(BusAddrRanges, " -- Dflt: %#llx : %#llx\n",dflt_iter->start,
dflt_iter->end);
}
for (PortIter portIter = portMap.begin();
portIter != portMap.end(); portIter++) {
bool subset = false;
for (AddrRangeIter dflt_iter = defaultRange.begin();
dflt_iter != defaultRange.end(); dflt_iter++) {
if ((portIter->first.start < dflt_iter->start &&
portIter->first.end >= dflt_iter->start) ||
(portIter->first.start < dflt_iter->end &&
portIter->first.end >= dflt_iter->end))
fatal("Devices can not set ranges that itersect the default set\
but are not a subset of the default set.\n");
if (portIter->first.start >= dflt_iter->start &&
portIter->first.end <= dflt_iter->end) {
subset = true;
DPRINTF(BusAddrRanges, " -- %#llx : %#llx is a SUBSET\n",
portIter->first.start, portIter->first.end);
}
}
if (portIter->second != id && !subset) {
resp.push_back(portIter->first);
DPRINTF(BusAddrRanges, " -- %#llx : %#llx\n",
portIter->first.start, portIter->first.end);
}
}
for (SnoopIter s_iter = snoopPorts.begin(); s_iter != snoopPorts.end();
s_iter++) {
if ((*s_iter)->getId() != id) {
snoop = true;
break;
}
}
}
int
Bus::findBlockSize(int id)
{
if (cachedBlockSizeValid)
return cachedBlockSize;
int max_bs = -1;
for (PortIter portIter = portMap.begin();
portIter != portMap.end(); portIter++) {
int tmp_bs = interfaces[portIter->second]->peerBlockSize();
if (tmp_bs > max_bs)
max_bs = tmp_bs;
}
for (SnoopIter s_iter = snoopPorts.begin();
s_iter != snoopPorts.end(); s_iter++) {
int tmp_bs = (*s_iter)->peerBlockSize();
if (tmp_bs > max_bs)
max_bs = tmp_bs;
}
if (max_bs <= 0)
max_bs = defaultBlockSize;
if (max_bs != 64)
warn_once("Blocksize found to not be 64... hmm... probably not.\n");
cachedBlockSize = max_bs;
cachedBlockSizeValid = true;
return max_bs;
}
unsigned int
Bus::drain(Event * de)
{
//We should check that we're not "doing" anything, and that noone is
//waiting. We might be idle but have someone waiting if the device we
//contacted for a retry didn't actually retry.
if (curTick >= tickNextIdle && retryList.size() == 0) {
return 0;
} else {
drainEvent = de;
return 1;
}
}
void
Bus::startup()
{
if (tickNextIdle < curTick)
tickNextIdle = (curTick / clock) * clock + clock;
}
Bus *
BusParams::create()
{
return new Bus(name, bus_id, clock, width, responder_set, block_size);
}