gem5 - gem5

Age	Commit message (Collapse)	Author
2015-07-07	sim: Decouple draining from the SimObject hierarchy	Andreas Sandberg
	Draining is currently done by traversing the SimObject graph and calling drain()/drainResume() on the SimObjects. This is not ideal when non-SimObjects (e.g., ports) need draining since this means that SimObjects owning those objects need to be aware of this. This changeset moves the responsibility for finding objects that need draining from SimObjects and the Python-side of the simulator to the DrainManager. The DrainManager now maintains a set of all objects that need draining. To reduce the overhead in classes owning non-SimObjects that need draining, objects inheriting from Drainable now automatically register with the DrainManager. If such an object is destroyed, it is automatically unregistered. This means that drain() and drainResume() should never be called directly on a Drainable object. While implementing the new functionality, the DrainManager has now been made thread safe. In practice, this means that it takes a lock whenever it manipulates the set of Drainable objects since SimObjects in different threads may create Drainable objects dynamically. Similarly, the drain counter is now an atomic_uint, which ensures that it is manipulated correctly when objects signal that they are done draining. A nice side effect of these changes is that it makes the drain state changes stricter, which the simulation scripts can exploit to avoid redundant drains.
2015-03-02	mem: Add option to force in-order insertion in PacketQueue	Stephan Diestelhorst
	By default, the packet queue is ordered by the ticks of the to-be-sent packages. With the recent modifications of packages sinking their header time when their resposne leaves the caches, there could be cases of MSHR targets being allocated and ordered A, B, but their responses being sent out in the order B,A. This led to inconsistencies in bus traffic, in particular the snoop filter observing first a ReadExResp and later a ReadRespWithInv. Logically, these were ordered the other way around behind the MSHR, but due to the timing adjustments when inserting into the PacketQueue, they were sent out in the wrong order on the bus, confusing the snoop filter. This patch adds a flag (off by default) such that these special cases can request in-order insertion into the packet queue, which might offset timing slighty. This is expected to occur rarely and not affect timing results.
2015-03-02	mem: Split port retry for all different packet classes	Andreas 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.
2014-02-23	ruby: Simplify RubyPort flow control and routing	Andreas Hansson
	This patch simplfies the retry logic in the RubyPort, avoiding redundant attributes, and enforcing more stringent checks on the interactions with the normal ports. The patch also simplifies the routing done by the RubyPort, using the port identifiers instead of a heavy-weight sender state. The patch also fixes a bug in the sending of responses from PIO ports. Previously these responses bypassed the queue in the queued port, and ignored the return value, potentially leading to response packets being lost. Committed by: Nilay Vaish <nilay@cs.wisc.edu>
2013-10-17	mem: Add PortID to QueuedMasterPort constructor	Sascha Bischoff
	This patch adds the PortID to the QueuedMasterPort. This allows a PortID to be specified as it previously was set to the detault value of -1.
2012-11-02	sim: Move the draining interface into a separate base class	Andreas 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.
2012-08-22	Port: Extend the QueuedPort interface and use where appropriate	Andreas Hansson
	This patch extends the queued port interfaces with methods for scheduling the transmission of a timing request/response. The methods are named similar to the corresponding sendTiming(Snoop)Req/Resp, replacing the "send" with "sched". As the queues are currently unbounded, the methods always succeed and hence do not return a value. This functionality was previously provided in the subclasses by calling PacketQueue::schedSendTiming with the appropriate parameters. With this change, there is no need to introduce these extra methods in the subclasses, and the use of the queued interface is more uniform and explicit.
2012-05-01	MEM: Separate requests and responses for timing accesses	Andreas 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.
2012-03-30	MEM: 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.
2012-03-22	MEM: Split SimpleTimingPort into PacketQueue and ports	Andreas Hansson
	This patch decouples the queueing and the port interactions to simplify the introduction of the master and slave ports. By separating the queueing functionality from the port itself, it becomes much easier to distinguish between master and slave ports, and still retain the queueing ability for both (without code duplication). As part of the split into a PacketQueue and a port, there is now also a hierarchy of two port classes, QueuedPort and SimpleTimingPort. The QueuedPort is useful for ports that want to leave the packet transmission of outgoing packets to the queue and is used by both master and slave ports. The SimpleTimingPort inherits from the QueuedPort and adds the implemention of recvTiming and recvFunctional through recvAtomic. The PioPort and MessagePort are cleaned up as part of the changes. --HG-- rename : src/mem/tport.cc => src/mem/packet_queue.cc rename : src/mem/tport.hh => src/mem/packet_queue.hh