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path: root/src/mem/bus.hh
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2013-03-26mem: Separate waiting for the bus and waiting for a peerAndreas Hansson
This patch splits the retryList into a list of ports that are waiting for the bus itself to become available, and a map that tracks the ports where forwarding failed due to a peer not accepting the packet. Thus, when a retry reaches the bus, it can be sent to the appropriate port that initiated that transaction. As a consequence of this patch, only ports that are really ready to go will get a retry, thus reducing the amount of redundant failed attempts. This patch also makes it easier to reason about the order of servicing requests as the ports waiting for the bus are now clearly FIFO and much easier to change if desired.
2013-03-26mem: Introduce a variable for the retrying portAndreas Hansson
This patch introduces a variable to keep track of the retrying port instead of relying on it being the front of the retryList. Besides the improvement in readability, this patch is a step towards separating out the two cases where a port is waiting for the bus to be free, and where the forwarding did not succeed and the bus is waiting for a retry to pass on to the original initiator of the transaction. The changes made are currently such that the regressions are not affected. This is ensured by always prioritizing the currently retrying port and putting it back at the front of the retry list.
2013-03-01mem: Merge ranges in bus before passing them onAndreas Hansson
This patch adds basic merging of address ranges to the bus, such that interleaved ranges are merged together before being passed on by the bus. As such, the bus aggregates the address ranges of the connected slave ports and then passes on the merged ranges through its master ports. The bus thus hides the complexity of the interleaved ranges and only exposes contigous ranges to the surrounding system. As part of this patch, the bus ranges are also cached for any future queries.
2013-02-19mem: Make packet bus-related time accounting relativeAndreas Hansson
This patch changes the bus-related time accounting done in the packet to be relative. Besides making it easier to align the cache timing to cache clock cycles, it also makes it possible to create a Last-Level Cache (LLC) directly to a memory controller without a bus inbetween. The bus is unique in that it does not ever make the packets wait to reflect the time spent forwarding them. Instead, the cache is currently responsible for making the packets wait. Thus, the bus annotates the packets with the time needed for the first word to appear, and also the last word. The cache then delays the packets in its queues before passing them on. It is worth noting that every object attached to a bus (devices, memories, bridges, etc) should be doing this if we opt for keeping this way of accounting for the bus timing.
2013-02-19sim: Make clock private and access using clockPeriod()Andreas Hansson
This patch makes the clock member private to the ClockedObject and forces all children to access it using clockPeriod(). This makes it impossible to inadvertently change the clock, and also makes it easier to transition to a situation where the clock is derived from e.g. a clock domain, or through a multiplier.
2013-01-07base: Encapsulate the underlying fields in AddrRangeAndreas Hansson
This patch makes the start and end address private in a move to prevent direct manipulation and matching of ranges based on these fields. This is done so that a transition to ranges with interleaving support is possible. As a result of hiding the start and end, a number of member functions are needed to perform the comparisons and manipulations that previously took place directly on the members. An accessor function is provided for the start address, and a function is added to test if an address is within a range. As a result of the latter the != and == operator is also removed in favour of the member function. A member function that returns a string representation is also created to allow debug printing. In general, this patch does not add any functionality, but it does take us closer to a situation where interleaving (and more cleverness) can be added under the bonnet without exposing it to the user. More on that in a later patch.
2012-11-02sim: Move the draining interface into a separate base classAndreas Sandberg
This patch moves the draining interface from SimObject to a separate class that can be used by any object needing draining. However, objects not visible to the Python code (i.e., objects not deriving from SimObject) still depend on their parents informing them when to drain. This patch also gets rid of the CountedDrainEvent (which isn't really an event) and replaces it with a DrainManager.
2012-10-15Port: Add protocol-agnostic ports in the port hierarchyAndreas Hansson
This patch adds an additional level of ports in the inheritance hierarchy, separating out the protocol-specific and protocl-agnostic parts. All the functionality related to the binding of ports is now confined to use BaseMaster/BaseSlavePorts, and all the protocol-specific parts stay in the Master/SlavePort. In the future it will be possible to add other protocol-specific implementations. The functions used in the binding of ports, i.e. getMaster/SlavePort now use the base classes, and the index parameter is updated to use the PortID typedef with the symbolic InvalidPortID as the default.
2012-10-15Mem: Use deque instead of list for bus retriesAndreas Hansson
This patch changes the data structure used to keep track of ports that should be told to retry. As the bus is doing this in an FCFS way, there is no point having a list. A deque is a better match (and is at least in theory a better choice from a performance point of view).
2012-10-15Mem: Use range operations in bus in preparation for stripingAndreas Hansson
This patch transitions the bus to use the AddrRange operations instead of directly accessing the start and end. The change facilitates the move to a more elaborate AddrRange class that also supports address striping in the bus by specifying interleaving bits in the ranges. Two new functions are added to the AddrRange to determine if two ranges intersect, and if one is a subset of another. The bus propagation of address ranges is also tweaked such that an update is only propagated if the bus received information from all the downstream slave modules. This avoids the iteration and need for the cycle-breaking scheme that was previously used.
2012-10-11Mem: Determine bus block size during initialisationAndreas Hansson
This patch moves the block size computation from findBlockSize to initialisation time, once all the neighbouring ports are connected. There is no need to dynamically update the block size, and the caching of the value effectively avoided that anyhow. This is very similar to what was already in place, just with a slightly leaner implementation.
2012-09-21Mem: Tidy up bus member variables typesAndreas Hansson
This patch merely tidies up the types used for the bus member variables. It also makes the constant ones const.
2012-09-19AddrRange: Transition from Range<T> to AddrRangeAndreas Hansson
This patch takes the final plunge and transitions from the templated Range class to the more specific AddrRange. In doing so it changes the obvious Range<Addr> to AddrRange, and also bumps the range_map to be AddrRangeMap. In addition to the obvious changes, including the removal of redundant includes, this patch also does some house keeping in preparing for the introduction of address interleaving support in the ranges. The Range class is also stripped of all the functionality that is never used. --HG-- rename : src/base/range.hh => src/base/addr_range.hh rename : src/base/range_map.hh => src/base/addr_range_map.hh
2012-08-21Clock: Move the clock and related functions to ClockedObjectAndreas Hansson
This patch moves the clock of the CPU, bus, and numerous devices to the new class ClockedObject, that sits in between the SimObject and MemObject in the class hierarchy. Although there are currently a fair amount of MemObjects that do not make use of the clock, they potentially should do so, e.g. the caches should at some point have the same clock as the CPU, potentially with a 1:n ratio. This patch does not introduce any new clock objects or object hierarchies (clusters, clock domains etc), but is still a step in the direction of having a more structured approach clock domains. The most contentious part of this patch is the serialisation of clocks that some of the modules (but not all) did previously. This serialisation should not be needed as the clock is set through the parameters even when restoring from the checkpoint. In other words, the state is "stored" in the Python code that creates the modules. The nextCycle methods are also simplified and the clock phase parameter of the CPU is removed (this could be part of a clock object once they are introduced).
2012-07-09Bus: Split the bus into separate request/response layersAndreas Hansson
This patch splits the existing buses into multiple layers. The non-coherent bus is split into a request and a response layer, and the coherent bus adds an additional layer for the snoop responses. The layer is modified to be templatised on the port type, such that the different layers can have retryLists with either master or slave ports. This patch also removes the dynamic cast from the retry, as previously promised when moving the recvRetry from the port base class to the master/slave port respectively. Overall, the split bus more closely reflects any modern on-chip bus and should be at step in the right direction. From this point, it would be reasonable straight forward to add separate layers (and thus contention points and arbitration) for each port and thus create a true crossbar. The regressions all produce the correct output, but have varying degrees of changes to their statistics. A separate patch will be pushed with the updates to the reference statistics.
2012-07-09Bus: Add a notion of layers to the busesAndreas Hansson
This patch moves all flow control, arbitration and state information into a bus layer. The layer is thus responsible for all the state transitions, and for keeping hold of the retry list. Consequently the layer is also responsible for the draining. With this change, the non-coherent and coherent bus are given a single layer to avoid changing any temporal behaviour, but the patch opens up for adding more layers.
2012-07-09Bus: Replace tickNextIdle and inRetry with a state variableAndreas Hansson
This patch adds a state enum and member variable in the bus, tracking the bus state, thus eliminating the need for tickNextIdle and inRetry, and fixing an issue that allowed the bus to be occupied by multiple packets at once (hopefully it also makes it easier to understand the code). The bus, in its current form, uses tickNextIdle and inRetry to keep track of the state of the bus. However, it only updates tickNextIdle _after_ forwarding a packet using sendTiming, and the result is that the bus is still seen as idle, and a module that receives the packet and starts transmitting new packets in zero time will still see the bus as idle (and this is done by a number of DMA devices). The issue can also be seen in isOccupied where the bus calls reschedule on an event instead of schedule. This patch addresses the problem by marking the bus as _not_ idle already by the time we conclude that the bus is not occupied and we will deal with the packet. As a result of not allowing multiple packets to occupy the bus, some regressions have slight changes in their statistics. A separate patch updates these accordingly. Further ahead, a follow-on patch will introduce a separate state variable for request/responses/snoop responses, and thus implement a split request/response bus with separate flow control for the different message types (even further ahead it will introduce a multi-layer bus).
2012-07-09Port: Make getAddrRanges constAndreas Hansson
This patch makes getAddrRanges const throughout the code base. There is no reason why it should not be, and making it const prevents adding any unintentional side-effects.
2012-05-31Bus: Split the bus into a non-coherent and coherent busAndreas Hansson
This patch introduces a class hierarchy of buses, a non-coherent one, and a coherent one, splitting the existing bus functionality. By doing so it also enables further specialisation of the two types of buses. A non-coherent bus connects a number of non-snooping masters and slaves, and routes the request and response packets based on the address. The request packets issued by the master connected to a non-coherent bus could still snoop in caches attached to a coherent bus, as is the case with the I/O bus and memory bus in most system configurations. No snoops will, however, reach any master on the non-coherent bus itself. The non-coherent bus can be used as a template for modelling PCI, PCIe, and non-coherent AMBA and OCP buses, and is typically used for the I/O buses. A coherent bus connects a number of (potentially) snooping masters and slaves, and routes the request and response packets based on the address, and also forwards all requests to the snoopers and deals with the snoop responses. The coherent bus can be used as a template for modelling QPI, HyperTransport, ACE and coherent OCP buses, and is typically used for the L1-to-L2 buses and as the main system interconnect. The configuration scripts are updated to use a NoncoherentBus for all peripheral and I/O buses. A bit of minor tidying up has also been done. --HG-- rename : src/mem/bus.cc => src/mem/coherent_bus.cc rename : src/mem/bus.hh => src/mem/coherent_bus.hh rename : src/mem/bus.cc => src/mem/noncoherent_bus.cc rename : src/mem/bus.hh => src/mem/noncoherent_bus.hh
2012-05-30Bus: Remove redundant packet parameter from isOccupiedAndreas Hansson
This patch merely remove the Packet* from the isOccupied member function. Historically this was used to check if the packet was an express snoop, but this is now done outside this function (where relevant).
2012-05-30Bus: Turn the PortId into a transport function parameterAndreas Hansson
The main aim of this patch is to arrive at a suitable port interface for vector ports, including both the packet and the port id. This patch changes the bus transport functions (recvFunctional/Atomic/Timing) to require a PortId parameter indicating the source port. Previously this information was passed by setting the source field of the packet, and this is only required in the case of a timing request. With this patch, the use of the source and destination field is also more restrictive, as they are only needed for timing accesses. The modifications to these fields for atomic snoops is now removed entirely, also making minor modifications to the cache.
2012-05-30Packet: Unify the use of PortID in packet and portAndreas Hansson
This patch removes the Packet::NodeID typedef and unifies it with the Port::PortId. The src and dest fields in the packet are used to hold a port id (e.g. in the bus), and thus the two should actually be the same. The typedef PortID is now global (in base/types.hh) and aligned with the ThreadID in terms of capitalisation and naming of the InvalidPortID constant. Before this patch, two flags were used for valid destination and source, rather than relying on a named value (InvalidPortID), and this is now redundant, as the src and dest field themselves are sufficient to tell whether the current value is a valid port identifier or not. Consequently, the VALID_SRC and VALID_DST are removed. As part of the cleaning up, a number of int parameters and local variables are updated to use PortID. Note that Ruby still has its own NodeID typedef. Furthermore, the MemObject getMaster/SlavePort still has an int idx parameter with a default value of -1 which should eventually change to PortID idx = InvalidPortID.
2012-05-01MEM: Separate requests and responses for timing accessesAndreas Hansson
This patch moves send/recvTiming and send/recvTimingSnoop from the Port base class to the MasterPort and SlavePort, and also splits them into separate member functions for requests and responses: send/recvTimingReq, send/recvTimingResp, and send/recvTimingSnoopReq, send/recvTimingSnoopResp. A master port sends requests and receives responses, and also receives snoop requests and sends snoop responses. A slave port has the reciprocal behaviour as it receives requests and sends responses, and sends snoop requests and receives snoop responses. For all MemObjects that have only master ports or slave ports (but not both), e.g. a CPU, or a PIO device, this patch merely adds more clarity to what kind of access is taking place. For example, a CPU port used to call sendTiming, and will now call sendTimingReq. Similarly, a response previously came back through recvTiming, which is now recvTimingResp. For the modules that have both master and slave ports, e.g. the bus, the behaviour was previously relying on branches based on pkt->isRequest(), and this is now replaced with a direct call to the apprioriate member function depending on the type of access. Please note that send/recvRetry is still shared by all the timing accessors and remains in the Port base class for now (to maintain the current bus functionality and avoid changing the statistics of all regressions). The packet queue is split into a MasterPort and SlavePort version to facilitate the use of the new timing accessors. All uses of the PacketQueue are updated accordingly. With this patch, the type of packet (request or response) is now well defined for each type of access, and asserts on pkt->isRequest() and pkt->isResponse() are now moved to the appropriate send member functions. It is also worth noting that sendTimingSnoopReq no longer returns a boolean, as the semantics do not alow snoop requests to be rejected or stalled. All these assumptions are now excplicitly part of the port interface itself.
2012-04-25MEM: Use base class Master/SlavePort pointers in the busAndreas Hansson
This patch makes some rather trivial simplifications to the bus in that it changes the use of BusMasterPort and BusSlavePort pointers to simply use MasterPort and SlavePort (iterators are also updated accordingly). This change is a step towards a future patch that introduces a separation of the interface and the structural port itself.
2012-04-25MEM: Add the PortId type and a corresponding id field to PortAndreas Hansson
This patch introduces the PortId type, moves the definition of INVALID_PORT_ID to the Port class, and also gives every port an id to reflect the fact that each element in a vector port has an identifier/index. Previously the bus and Ruby testers (and potentially other users of the vector ports) added the id field in their port subclasses, and now this functionality is always present as it is moved to the base class.
2012-04-14MEM: Separate snoops and normal memory requests/responsesAndreas Hansson
This patch introduces port access methods that separates snoop request/responses from normal memory request/responses. The differentiation is made for functional, atomic and timing accesses and builds on the introduction of master and slave ports. Before the introduction of this patch, the packets belonging to the different phases of the protocol (request -> [forwarded snoop request -> snoop response]* -> response) all use the same port access functions, even though the snoop packets flow in the opposite direction to the normal packet. That is, a coherent master sends normal request and receives responses, but receives snoop requests and sends snoop responses (vice versa for the slave). These two distinct phases now use different access functions, as described below. Starting with the functional access, a master sends a request to a slave through sendFunctional, and the request packet is turned into a response before the call returns. In a system without cache coherence, this is all that is needed from the functional interface. For the cache-coherent scenario, a slave also sends snoop requests to coherent masters through sendFunctionalSnoop, with responses returned within the same packet pointer. This is currently used by the bus and caches, and the LSQ of the O3 CPU. The send/recvFunctional and send/recvFunctionalSnoop are moved from the Port super class to the appropriate subclass. Atomic accesses follow the same flow as functional accesses, with request being sent from master to slave through sendAtomic. In the case of cache-coherent ports, a slave can send snoop requests to a master through sendAtomicSnoop. Just as for the functional access methods, the atomic send and receive member functions are moved to the appropriate subclasses. The timing access methods are different from the functional and atomic in that requests and responses are separated in time and send/recvTiming are used for both directions. Hence, a master uses sendTiming to send a request to a slave, and a slave uses sendTiming to send a response back to a master, at a later point in time. Snoop requests and responses travel in the opposite direction, similar to what happens in functional and atomic accesses. With the introduction of this patch, it is possible to determine the direction of packets in the bus, and no longer necessary to look for both a master and a slave port with the requested port id. In contrast to the normal recvFunctional, recvAtomic and recvTiming that are pure virtual functions, the recvFunctionalSnoop, recvAtomicSnoop and recvTimingSnoop have a default implementation that calls panic. This is to allow non-coherent master and slave ports to not implement these functions.
2012-03-30MEM: Introduce the master/slave port sub-classes in C++William Wang
This patch introduces the notion of a master and slave port in the C++ code, thus bringing the previous classification from the Python classes into the corresponding simulation objects and memory objects. The patch enables us to classify behaviours into the two bins and add assumptions and enfore compliance, also simplifying the two interfaces. As a starting point, isSnooping is confined to a master port, and getAddrRanges to slave ports. More of these specilisations are to come in later patches. The getPort function is not getMasterPort and getSlavePort, and returns a port reference rather than a pointer as NULL would never be a valid return value. The default implementation of these two functions is placed in MemObject, and calls fatal. The one drawback with this specific patch is that it requires some code duplication, e.g. QueuedPort becomes QueuedMasterPort and QueuedSlavePort, and BusPort becomes BusMasterPort and BusSlavePort (avoiding multiple inheritance). With the later introduction of the port interfaces, moving the functionality outside the port itself, a lot of the duplicated code will disappear again.
2012-03-22MEM: Unify bus access methods and prepare for master/slave splitAndreas Hansson
This patch unifies the recvFunctional, recvAtomic and recvTiming to all be based on a similar structure: 1) extract information about the incoming packet, 2) send it out to the appropriate snoopers, 3) determine where it is going, and 4) forward it to the right destination. The naming of variables across the different access functions is now consistent as well. Additionally, the patch introduces the member functions releaseBus and retryWaiting to better distinguish between the two cases when we should tell a sender to retry. The first case is when the bus goes from busy to idle, and the second case is when it receives a retry from a destination that did not immediatelly accept a packet. As a very minor change, the MMU debug flag is no longer used in the bus.
2012-02-24MEM: Move port creation to the memory object(s) constructionAndreas Hansson
This patch moves all port creation from the getPort method to be consistently done in the MemObject's constructor. This is possible thanks to the Swig interface passing the length of the vector ports. Previously there was a mix of: 1) creating the ports as members (at object construction time) and using getPort for the name resolution, or 2) dynamically creating the ports in the getPort call. This is now uniform. Furthermore, objects that would not be complete without a port have these ports as members rather than having pointers to dynamically allocated ports. This patch also enables an elaboration-time enumeration of all the ports in the system which can be used to determine the masterId.
2012-02-24MEM: Fatal when no port can be found for an addressAndreas Hansson
This patch adds a check in the findPort method to ensure that an invalid port id is never returned. Previously this could happen if no default port was set, and no address matched the request, in which case -1 was returned causing a SEGFAULT when using the id to index in the port array. To clean things up further a symbolic name is added for the invalid port id.
2012-02-09MEM: Remove onRetryList from BusPort and rely on retryListAndreas Hansson
This patch removes the onRetryList field from the BusPort class and entirely relies on the retryList which holds all ports that are waiting to retry. The onRetryList field and the retryList were previously used with overloaded functionalities and only one is really needed (there were also checks to assert they held the same information). After this patch the bus ports will be split into master and slave ports and this simplifies that transition.
2012-01-17MEM: Make the bus default port yet another portAndreas Hansson
This patch removes the idiosyncratic nature of the default bus port and makes it yet another port in the list of interfaces. Rather than having a specific pointer to the default port we merely track the identifier of this port. This change makes future port diversification easier and overall cleans up the bus code.
2012-01-17MEM: Remove the functional ports from the memory systemWilliam Wang
The functional ports are no longer used and this patch cleans up the legacy that is still present in buses, memories, CPUs etc. Note that this does not refer to the class FunctionalPort (already removed), but rather ports with the name (and use) functional.
2012-01-17MEM: Separate queries for snooping and address rangesAndreas Hansson
This patch simplifies the address-range determination mechanism and also unifies the naming across ports and devices. It further splits the queries for determining if a port is snooping and what address ranges it responds to (aiming towards a separation of cache-maintenance ports and pure memory-mapped ports). Default behaviours are such that most ports do not have to define isSnooping, and master ports need not implement getAddrRanges.
2012-01-17MEM: Remove Port removeConn and MemObject deletePortRefsAndreas Hansson
Cleaning up and simplifying the ports and going towards a more strict elaboration-time creation and binding of the ports.
2011-04-15includes: sort all includesNathan Binkert
2010-08-17bus: clean up default responder code.Steve Reinhardt
Clean up some minor things left over from the default responder change in rev 9af6fb59752f. Mostly renaming the 'responder_set' param to 'use_default_range' to actually reflect what it does... old name wasn't that descriptive in the first place, but now it really doesn't make sense at all. Also got rid of the bogus obsolete assignment to 'bus.responder' which used to be a parameter but now is interpreted as an implicit child assignment, and which was giving me problems in the config restructuring to come. (A good argument for not allowing implicit child assignments, IMO, but that's water under the bridge, I'm afraid.) Also moved the Bus constructor to the .cc file since that's where it should have been all along.
2009-06-04types: clean up types, especially signed vs unsignedNathan Binkert
2009-05-17includes: sort includes againNathan Binkert
2009-05-17includes: use base/types.hh not inttypes.h or stdint.hNathan Binkert
2008-06-28Backed out changeset 94a7bb476fca: caused memory leak.Steve Reinhardt
2008-06-21Generate more useful error messages for unconnected ports.Steve Reinhardt
Force all non-default ports to provide a name and an owner in the constructor.
2008-03-17Restructure bus timing calcs to cope with pkt being deleted by target.Steve Reinhardt
--HG-- extra : convert_revision : db8497e73a44f2a06aab121e797e88b4c0c31330
2008-02-26Bus: Fix the bus timing to be more realistic.Gabe Black
--HG-- extra : convert_revision : acd70dc98ab840e55b114706fbb6afb2a95e54bc
2008-02-06Make the Event::description() a const functionStephen Hines
--HG-- extra : convert_revision : c7768d54d3f78685e93920069f5485083ca989c0
2007-08-30params: Deprecate old-style constructors; update most SimObject constructors.Miles Kaufmann
SimObjects not yet updated: - Process and subclasses - BaseCPU and subclasses The SimObject(const std::string &name) constructor was removed. Subclasses that still rely on that behavior must call the parent initializer as : SimObject(makeParams(name)) --HG-- extra : convert_revision : d6faddde76e7c3361ebdbd0a7b372a40941c12ed
2007-08-10DMA: Add IOCache and fix bus bridge to optionally only send requests oneAli Saidi
way so a cache can handle partial block requests for i/o devices. --HG-- extra : convert_revision : a68b5ae826731bc87ed93eb7ef326a2393053964
2007-08-08Port, StaticInst: Revert unnecessary changes.Vincentius Robby
--HG-- extra : convert_revision : e6ef262bbbc5ad53498e55caac1897e6cc2a61e6
2007-08-08alpha: Make the TLB cache to actually work.Vincentius Robby
Improve MRU checking for StaticInst, Bus, TLB --HG-- extra : convert_revision : 9116b5655cd2986aeb4205438aad4a0f5a440006
2007-08-04port: Implement cache for port interfaces and rangesVincentius Robby
--HG-- extra : convert_revision : d7cbec7c277fb8f4d8846203caae36ce629602d5