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2015-07-07sim: Refactor the serialization base classAndreas Sandberg
Objects that are can be serialized are supposed to inherit from the Serializable class. This class is meant to provide a unified API for such objects. However, so far it has mainly been used by SimObjects due to some fundamental design limitations. This changeset redesigns to the serialization interface to make it more generic and hide the underlying checkpoint storage. Specifically: * Add a set of APIs to serialize into a subsection of the current object. Previously, objects that needed this functionality would use ad-hoc solutions using nameOut() and section name generation. In the new world, an object that implements the interface has the methods serializeSection() and unserializeSection() that serialize into a named /subsection/ of the current object. Calling serialize() serializes an object into the current section. * Move the name() method from Serializable to SimObject as it is no longer needed for serialization. The fully qualified section name is generated by the main serialization code on the fly as objects serialize sub-objects. * Add a scoped ScopedCheckpointSection helper class. Some objects need to serialize data structures, that are not deriving from Serializable, into subsections. Previously, this was done using nameOut() and manual section name generation. To simplify this, this changeset introduces a ScopedCheckpointSection() helper class. When this class is instantiated, it adds a new /subsection/ and subsequent serialization calls during the lifetime of this helper class happen inside this section (or a subsection in case of nested sections). * The serialize() call is now const which prevents accidental state manipulation during serialization. Objects that rely on modifying state can use the serializeOld() call instead. The default implementation simply calls serialize(). Note: The old-style calls need to be explicitly called using the serializeOld()/serializeSectionOld() style APIs. These are used by default when serializing SimObjects. * Both the input and output checkpoints now use their own named types. This hides underlying checkpoint implementation from objects that need checkpointing and makes it easier to change the underlying checkpoint storage code.
2012-06-05sim: Provide a framework for detecting out of data checkpoints and migrating ↵Ali Saidi
them.
2011-06-02copyright: clean up copyright blocksNathan Binkert
2011-02-11Timesync: Make sure timesync event is setup after curTick is unserializedAli Saidi
Setup initial timesync event in initState or loadState so that curTick has been updated to the new value, otherwise the event is scheduled in the past.
2011-01-19Time: Add a mechanism to prevent M5 from running faster than real time.Gabe Black
M5 skips over any simulated time where it doesn't have any work to do. When the simulation is active, the time skipped is short and the work done at any point in time is relatively substantial. If the time between events is long and/or the work to do at each event is small, it's possible for simulated time to pass faster than real time. When running a benchmark that can be good because it means the simulation will finish sooner in real time. When interacting with the real world through, for instance, a serial terminal or bridge to a real network, this can be a problem. Human or network response time could be greatly exagerated from the perspective of the simulation and make simulated events happen "too soon" from an external perspective. This change adds the capability to force the simulation to run no faster than real time. It does so by scheduling a periodic event that checks to see if its simulated period is shorter than its real period. If it is, it stalls the simulation until they're equal. This is called time syncing. A future change could add pseudo instructions which turn time syncing on and off from within the simulation. That would allow time syncing to be used for the interactive parts of a session but then turned off when running a benchmark using the m5 utility program inside a script. Time syncing would probably not happen anyway while running a benchmark because there would be plenty of work for M5 to do, but the event overhead could be avoided.