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path: root/src/mem/SimpleMemory.py
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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.
2012-04-06MEM: 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