2014-09-20 23:18:26 +02:00
|
|
|
/*
|
|
|
|
* Copyright (c) 2013 ARM Limited
|
|
|
|
* All rights reserved
|
|
|
|
*
|
|
|
|
* The license below extends only to copyright in the software and shall
|
|
|
|
* not be construed as granting a license to any other intellectual
|
|
|
|
* property including but not limited to intellectual property relating
|
|
|
|
* to a hardware implementation of the functionality of the software
|
|
|
|
* licensed hereunder. You may use the software subject to the license
|
|
|
|
* terms below provided that you ensure that this notice is replicated
|
|
|
|
* unmodified and in its entirety in all distributions of the software,
|
|
|
|
* modified or unmodified, in source code or in binary form.
|
|
|
|
*
|
|
|
|
* 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: Stephan Diestelhorst <stephan.diestelhorst@arm.com>
|
|
|
|
*/
|
|
|
|
|
|
|
|
/**
|
|
|
|
* @file
|
|
|
|
* Definition of a snoop filter.
|
|
|
|
*/
|
|
|
|
|
|
|
|
#ifndef __MEM_SNOOP_FILTER_HH__
|
|
|
|
#define __MEM_SNOOP_FILTER_HH__
|
|
|
|
|
|
|
|
#include <utility>
|
|
|
|
|
|
|
|
#include "base/hashmap.hh"
|
|
|
|
#include "mem/packet.hh"
|
|
|
|
#include "mem/port.hh"
|
2015-07-03 16:14:44 +02:00
|
|
|
#include "mem/qport.hh"
|
2014-09-20 23:18:26 +02:00
|
|
|
#include "params/SnoopFilter.hh"
|
|
|
|
#include "sim/sim_object.hh"
|
|
|
|
#include "sim/system.hh"
|
|
|
|
|
|
|
|
/**
|
|
|
|
* This snoop filter keeps track of which connected port has a
|
|
|
|
* particular line of data. It can be queried (through lookup*) on
|
|
|
|
* memory requests from above (reads / writes / ...); and also from
|
|
|
|
* below (snoops). The snoop filter precisely knows about the location
|
|
|
|
* of lines "above" it through a map from cache line address to
|
|
|
|
* sharers/ports. The snoop filter ties into the flows of requests
|
|
|
|
* (when they succeed at the lower interface), regular responses from
|
|
|
|
* below and also responses from sideway's caches (in update*). This
|
|
|
|
* allows the snoop filter to model cache-line residency by snooping
|
|
|
|
* the messages.
|
|
|
|
*
|
|
|
|
* The tracking happens in two fields to be able to distinguish
|
|
|
|
* between in-flight requests (in requested) and already pulled in
|
|
|
|
* lines (in holder). This distinction is used for producing tighter
|
|
|
|
* assertions and tracking request completion. For safety, (requested
|
|
|
|
* | holder) should be notified and the requesting MSHRs will take
|
|
|
|
* care of ordering.
|
|
|
|
*
|
|
|
|
* Overall, some trickery is required because:
|
|
|
|
* (1) snoops are not followed by an ACK, but only evoke a response if
|
|
|
|
* they need to (hit dirty)
|
|
|
|
* (2) side-channel information is funnelled through direct modifications of
|
|
|
|
* pkt, instead of proper messages through the bus
|
|
|
|
* (3) there are no clean evict messages telling the snoop filter that a local,
|
|
|
|
* upper cache dropped a line, making the snoop filter pessimistic for now
|
|
|
|
* (4) ordering: there is no single point of order in the system. Instead,
|
|
|
|
* requesting MSHRs track order between local requests and remote snoops
|
|
|
|
*/
|
|
|
|
class SnoopFilter : public SimObject {
|
|
|
|
public:
|
2015-07-03 16:14:44 +02:00
|
|
|
typedef std::vector<QueuedSlavePort*> SnoopList;
|
2014-09-20 23:18:26 +02:00
|
|
|
|
|
|
|
SnoopFilter (const SnoopFilterParams *p) : SimObject(p),
|
|
|
|
linesize(p->system->cacheLineSize()), lookupLatency(p->lookup_latency)
|
|
|
|
{
|
|
|
|
}
|
|
|
|
|
|
|
|
/**
|
|
|
|
* Init a new snoop filter and tell it about all the slave ports of the
|
|
|
|
* enclosing bus.
|
|
|
|
*
|
|
|
|
* @param bus_slave_ports Vector of slave ports that the bus is attached to.
|
|
|
|
*/
|
2015-07-03 16:14:44 +02:00
|
|
|
void setSlavePorts(const SnoopList& bus_slave_ports) {
|
2014-09-20 23:18:26 +02:00
|
|
|
slavePorts = bus_slave_ports;
|
|
|
|
}
|
|
|
|
|
|
|
|
/**
|
|
|
|
* Lookup a request (from a slave port) in the snoop filter and return a
|
|
|
|
* list of other slave ports that need forwarding of the resulting snoops.
|
|
|
|
* Additionally, update the tracking structures with new request
|
|
|
|
* information.
|
|
|
|
*
|
|
|
|
* @param cpkt Pointer to the request packet. Not changed.
|
|
|
|
* @param slave_port Slave port where the request came from.
|
|
|
|
* @return Pair of a vector of snoop target ports and lookup latency.
|
|
|
|
*/
|
|
|
|
std::pair<SnoopList, Cycles> lookupRequest(const Packet* cpkt,
|
|
|
|
const SlavePort& slave_port);
|
|
|
|
|
|
|
|
/**
|
|
|
|
* For a successful request, update all data structures in the snoop filter
|
|
|
|
* reflecting the changes caused by that request
|
|
|
|
*
|
|
|
|
* @param cpkt Pointer to the request packet. Not changed.
|
|
|
|
* @param slave_port Slave port where the request came from.
|
|
|
|
* @param will_retry This request will retry on this bus / snoop filter
|
|
|
|
*/
|
|
|
|
void updateRequest(const Packet* cpkt, const SlavePort& slave_port,
|
|
|
|
bool will_retry);
|
|
|
|
|
|
|
|
/**
|
|
|
|
* Handle an incoming snoop from below (the master port). These can upgrade the
|
|
|
|
* tracking logic and may also benefit from additional steering thanks to the
|
|
|
|
* snoop filter.
|
|
|
|
* @param cpkt Pointer to const Packet containing the snoop.
|
|
|
|
* @return Pair with a vector of SlavePorts that need snooping and a lookup
|
|
|
|
* latency.
|
|
|
|
*/
|
|
|
|
std::pair<SnoopList, Cycles> lookupSnoop(const Packet* cpkt);
|
|
|
|
|
|
|
|
/**
|
|
|
|
* Let the snoop filter see any snoop responses that turn into request responses
|
|
|
|
* and indicate cache to cache transfers. These will update the corresponding
|
|
|
|
* state in the filter.
|
|
|
|
*
|
|
|
|
* @param cpkt Pointer to const Packet holding the snoop response.
|
|
|
|
* @param rsp_port SlavePort that sends the response.
|
|
|
|
* @param req_port SlavePort that made the original request and is the
|
|
|
|
* destination of the snoop response.
|
|
|
|
*/
|
|
|
|
void updateSnoopResponse(const Packet *cpkt, const SlavePort& rsp_port,
|
|
|
|
const SlavePort& req_port);
|
|
|
|
|
|
|
|
/**
|
|
|
|
* Pass snoop responses that travel downward through the snoop filter and let
|
|
|
|
* them update the snoop filter state. No additional routing happens.
|
|
|
|
*
|
|
|
|
* @param cpkt Pointer to const Packet holding the snoop response.
|
|
|
|
* @param rsp_port SlavePort that sends the response.
|
|
|
|
* @param req_port MasterPort through which the response leaves this cluster.
|
|
|
|
*/
|
|
|
|
void updateSnoopForward(const Packet *cpkt, const SlavePort& rsp_port,
|
|
|
|
const MasterPort& req_port);
|
|
|
|
|
|
|
|
/**
|
|
|
|
* Update the snoop filter with a response from below (outer / other cache,
|
|
|
|
* or memory) and update the tracking information in the snoop filter.
|
|
|
|
*
|
|
|
|
* @param cpkt Pointer to const Packet holding the snoop response.
|
|
|
|
* @param slave_port SlavePort that made the original request and is the target
|
|
|
|
* of this response.
|
|
|
|
*/
|
|
|
|
void updateResponse(const Packet *cpkt, const SlavePort& slave_port);
|
|
|
|
|
|
|
|
/**
|
|
|
|
* Simple factory methods for standard return values for lookupRequest
|
|
|
|
*/
|
|
|
|
std::pair<SnoopList, Cycles> snoopAll(Cycles latency) const
|
|
|
|
{
|
|
|
|
return std::make_pair(slavePorts, latency);
|
|
|
|
}
|
|
|
|
std::pair<SnoopList, Cycles> snoopSelected(const SnoopList& slave_ports,
|
|
|
|
Cycles latency) const
|
|
|
|
{
|
|
|
|
return std::make_pair(slave_ports, latency);
|
|
|
|
}
|
|
|
|
std::pair<SnoopList, Cycles> snoopDown(Cycles latency) const
|
|
|
|
{
|
|
|
|
SnoopList empty;
|
|
|
|
return std::make_pair(empty , latency);
|
|
|
|
}
|
|
|
|
|
2014-04-25 13:36:16 +02:00
|
|
|
virtual void regStats();
|
|
|
|
|
2014-09-20 23:18:26 +02:00
|
|
|
protected:
|
|
|
|
typedef uint64_t SnoopMask;
|
|
|
|
/**
|
|
|
|
* Per cache line item tracking a bitmask of SlavePorts who have an
|
|
|
|
* outstanding request to this line (requested) or already share a cache line
|
|
|
|
* with this address (holder).
|
|
|
|
*/
|
|
|
|
struct SnoopItem {
|
|
|
|
SnoopMask requested;
|
|
|
|
SnoopMask holder;
|
|
|
|
};
|
|
|
|
/**
|
|
|
|
* Convert a single port to a corresponding, one-hot bitmask
|
|
|
|
* @param port SlavePort that should be converted.
|
|
|
|
* @return One-hot bitmask corresponding to the port.
|
|
|
|
*/
|
|
|
|
SnoopMask portToMask(const SlavePort& port) const;
|
|
|
|
/**
|
|
|
|
* Convert multiple ports to a corresponding bitmask
|
|
|
|
* @param ports SnoopList that should be converted.
|
|
|
|
* @return Bitmask corresponding to the ports in the list.
|
|
|
|
*/
|
|
|
|
SnoopMask portListToMask(const SnoopList& ports) const;
|
|
|
|
/**
|
|
|
|
* Converts a bitmask of ports into the corresponing list of ports
|
|
|
|
* @param ports SnoopMask of the requested ports
|
|
|
|
* @return SnoopList containing all the requested SlavePorts
|
|
|
|
*/
|
|
|
|
SnoopList maskToPortList(SnoopMask ports) const;
|
|
|
|
|
|
|
|
private:
|
|
|
|
/** Simple hash set of cached addresses. */
|
|
|
|
m5::hash_map<Addr, SnoopItem> cachedLocations;
|
|
|
|
/** List of all attached slave ports. */
|
|
|
|
SnoopList slavePorts;
|
|
|
|
/** Cache line size. */
|
|
|
|
const unsigned linesize;
|
|
|
|
/** Latency for doing a lookup in the filter */
|
|
|
|
const Cycles lookupLatency;
|
2014-04-25 13:36:16 +02:00
|
|
|
|
|
|
|
/** Statistics */
|
|
|
|
Stats::Scalar totRequests;
|
|
|
|
Stats::Scalar hitSingleRequests;
|
|
|
|
Stats::Scalar hitMultiRequests;
|
|
|
|
|
|
|
|
Stats::Scalar totSnoops;
|
|
|
|
Stats::Scalar hitSingleSnoops;
|
|
|
|
Stats::Scalar hitMultiSnoops;
|
2014-09-20 23:18:26 +02:00
|
|
|
};
|
|
|
|
|
|
|
|
inline SnoopFilter::SnoopMask
|
|
|
|
SnoopFilter::portToMask(const SlavePort& port) const
|
|
|
|
{
|
|
|
|
unsigned id = (unsigned)port.getId();
|
|
|
|
assert(id != (unsigned)InvalidPortID);
|
|
|
|
assert((int)id < 8 * sizeof(SnoopMask));
|
|
|
|
|
|
|
|
return ((SnoopMask)1) << id;
|
|
|
|
}
|
|
|
|
|
|
|
|
inline SnoopFilter::SnoopMask
|
|
|
|
SnoopFilter::portListToMask(const SnoopList& ports) const
|
|
|
|
{
|
|
|
|
SnoopMask m = 0;
|
|
|
|
for (auto port = ports.begin(); port != ports.end(); ++port)
|
|
|
|
m |= portToMask(**port);
|
|
|
|
return m;
|
|
|
|
}
|
|
|
|
|
|
|
|
inline SnoopFilter::SnoopList
|
|
|
|
SnoopFilter::maskToPortList(SnoopMask port_mask) const
|
|
|
|
{
|
|
|
|
SnoopList res;
|
|
|
|
for (auto port = slavePorts.begin(); port != slavePorts.end(); ++port)
|
|
|
|
if (port_mask & portToMask(**port))
|
|
|
|
res.push_back(*port);
|
|
|
|
return res;
|
|
|
|
}
|
|
|
|
#endif // __MEM_SNOOP_FILTER_HH__
|