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path: root/src/mem/simple_mem.hh
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2015-07-07sim: Refactor and simplify the drain APIAndreas Sandberg
The drain() call currently passes around a DrainManager pointer, which is now completely pointless since there is only ever one global DrainManager in the system. It also contains vestiges from the time when SimObjects had to keep track of their child objects that needed draining. This changeset moves all of the DrainState handling to the Drainable base class and changes the drain() and drainResume() calls to reflect this. Particularly, the drain() call has been updated to take no parameters (the DrainManager argument isn't needed) and return a DrainState instead of an unsigned integer (there is no point returning anything other than 0 or 1 any more). Drainable objects should return either DrainState::Draining (equivalent to returning 1 in the old system) if they need more time to drain or DrainState::Drained (equivalent to returning 0 in the old system) if they are already in a consistent state. Returning DrainState::Running is considered an error. Drain done signalling is now done through the signalDrainDone() method in the Drainable class instead of using the DrainManager directly. The new call checks if the state of the object is DrainState::Draining before notifying the drain manager. This means that it is safe to call signalDrainDone() without first checking if the simulator has requested draining. The intention here is to reduce the code needed to implement draining in simple objects.
2015-03-02mem: Split port retry for all different packet classesAndreas Hansson
This patch fixes a long-standing isue with the port flow control. Before this patch the retry mechanism was shared between all different packet classes. As a result, a snoop response could get stuck behind a request waiting for a retry, even if the send/recv functions were split. This caused message-dependent deadlocks in stress-test scenarios. The patch splits the retry into one per packet (message) class. Thus, sendTimingReq has a corresponding recvReqRetry, sendTimingResp has recvRespRetry etc. Most of the changes to the code involve simply clarifying what type of request a specific object was accepting. The biggest change in functionality is in the cache downstream packet queue, facing the memory. This queue was shared by requests and snoop responses, and it is now split into two queues, each with their own flow control, but the same physical MasterPort. These changes fixes the previously seen deadlocks.
2013-08-19mem: Add an internal packet queue in SimpleMemoryAndreas Hansson
This patch adds a packet queue in SimpleMemory to avoid using the packet queue in the port (and thus have no involvement in the flow control). The port queue was bound to 100 packets, and as the SimpleMemory is modelling both a controller and an actual RAM, it potentially has a large number of packets in flight. There is currently no limit on the number of packets in the memory controller, but this could easily be added in a follow-on patch. As a result of the added internal storage, the functional access and draining is updated. Some minor cleaning up and renaming has also been done. The memtest regression changes as a result of this patch and the stats will be updated.
2012-11-02mem: fix use after free issue in memories until 4-phase work complete.Ali Saidi
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.
2012-09-25MEM: Put memory system document into doxygenDjordje Kovacevic
2012-09-18Mem: Add a maximum bandwidth to SimpleMemoryAndreas Hansson
This patch makes a minor addition to the SimpleMemory by enforcing a maximum data rate. The bandwidth is configurable, and a reasonable value (12.8GB/s) has been choosen as the default. The changes do add some complexity to the SimpleMemory, but they should definitely be justifiable as this enables a far more realistic setup using even this simple memory controller. The rate regulation is done for reads and writes combined to reflect the bidirectional data busses used by most (if not all) relevant memories. Moreover, the regulation is done per packet as opposed to long term, as it is the short term data rate (data bus width times frequency) that is the limiting factor. A follow-up patch bumps the stats for the regressions.
2012-07-12Mem: Make SimpleMemory single portedAndreas Hansson
This patch changes the simple memory to have a single slave port rather than a vector port. The simple memory makes no attempts at modelling the contention between multiple ports, and any such multiplexing and demultiplexing could be done in a bus (or crossbar) outside the memory controller. This scenario also matches with the ongoing work on a SimpleDRAM model, which will be a single-ported single-channel controller that can be used in conjunction with a bus (or crossbar) to create a multi-port multi-channel controller. There are only very few regressions that make use of the vector port, and these are all for functional accesses only. To facilitate these cases, memtest and memtest-ruby have been updated to also have a "functional" bus to perform the (de)multiplexing of the functional memory accesses.
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.
2012-04-06MEM: Enable multiple distributed generalized memoriesAndreas Hansson
This patch removes the assumption on having on single instance of PhysicalMemory, and enables a distributed memory where the individual memories in the system are each responsible for a single contiguous address range. All memories inherit from an AbstractMemory that encompasses the basic behaviuor of a random access memory, and provides untimed access methods. What was previously called PhysicalMemory is now SimpleMemory, and a subclass of AbstractMemory. All future types of memory controllers should inherit from AbstractMemory. To enable e.g. the atomic CPU and RubyPort to access the now distributed memory, the system has a wrapper class, called PhysicalMemory that is aware of all the memories in the system and their associated address ranges. This class thus acts as an infinitely-fast bus and performs address decoding for these "shortcut" accesses. Each memory can specify that it should not be part of the global address map (used e.g. by the functional memories by some testers). Moreover, each memory can be configured to be reported to the OS configuration table, useful for populating ATAG structures, and any potential ACPI tables. Checkpointing support currently assumes that all memories have the same size and organisation when creating and resuming from the checkpoint. A future patch will enable a more flexible re-organisation. --HG-- rename : src/mem/PhysicalMemory.py => src/mem/AbstractMemory.py rename : src/mem/PhysicalMemory.py => src/mem/SimpleMemory.py rename : src/mem/physical.cc => src/mem/abstract_mem.cc rename : src/mem/physical.hh => src/mem/abstract_mem.hh rename : src/mem/physical.cc => src/mem/simple_mem.cc rename : src/mem/physical.hh => src/mem/simple_mem.hh