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2015-12-07proto, probe: Add elastic trace probe to o3 cpuRadhika Jagtap
The elastic trace is a type of probe listener and listens to probe points in multiple stages of the O3CPU. The notify method is called on a probe point typically when an instruction successfully progresses through that stage. As different listener methods mapped to the different probe points execute, relevant information about the instruction, e.g. timestamps and register accesses, are captured and stored in temporary InstExecInfo class objects. When the instruction progresses through the commit stage, the timing and the dependency information about the instruction is finalised and encapsulated in a struct called TraceInfo. TraceInfo objects are collected in a list instead of writing them out to the trace file one a time. This is required as the trace is processed in chunks to evaluate order dependencies and computational delay in case an instruction does not have any register dependencies. By this we achieve a simpler algorithm during replay because every record in the trace can be hooked onto a record in its past. The instruction dependency trace is written out as a protobuf format file. A second trace containing fetch requests at absolute timestamps is written to a separate protobuf format file. If the instruction is not executed then it is not added to the trace. The code checks if the instruction had a fault, if it predicated false and thus previous register values were restored or if it was a load/store that did not have a request (e.g. when the size of the request is zero). In all these cases the instruction is set as executed by the Execute stage and is picked up by the commit probe listener. But a request is not issued and registers are not written. So practically, skipping these should not hurt the dependency modelling. If squashing results in squashing younger instructions, it may happen that the squash probe discards the inst and removes it from the temporary store but execute stage deals with the instruction in the next cycle which results in the execute probe seeing this inst as 'new' inst. A sequence number of the last processed trace record is used to trap these cases and not add to the temporary store. The elastic instruction trace and fetch request trace can be read in and played back by the TraceCPU.
2014-09-01mem: change the namespace Message to ProtoMessageNilay Vaish
The namespace Message conflicts with the Message data type used extensively in Ruby. Since Ruby is being moved to the same Master/Slave ports based configuration style as the rest of gem5, this conflict needs to be resolved. Hence, the namespace is being renamed to ProtoMessage.
2014-03-07mem: Edit proto Packet and enhance the python scriptRadhika Jagtap
This patch changes the decode script to output the optional fields of the proto message Packet, namely id and flags. The flags field is set by the communication monitor. The id field is useful for CPU trace experiments, e.g. linking the fetch side to decode side. It had to be renamed because it clashes with a built in python function id() for getting the "identity" of an object. This patch also takes a few common function definitions out from the multiple scripts and adds them to a protolib python module.
2013-03-26mem: Add a generic id field to the packet traceAndreas Hansson
This patch adds an optional generic 64-bit identifier field to the packet trace. This can be used to store the sequential number of the instruction that gave rise to the packet, thread id, master id, "sub"-master within a larger module etc. As the field is optional it has a marginal cost if not used.
2013-03-26mem: Add optional request flags to the packet traceAndreas Hansson
This patch adds an optional flags field to the packet trace to encode the request flags that contain information about whether the request is (un)cacheable, instruction fetch, preftech etc.
2013-01-07mem: Add tracing support in the communication monitorAndreas Hansson
This patch adds packet tracing to the communication monitor using a protobuf as the mechanism for creating the trace. If no file is specified, then the tracing is disabled. If a file is specified, then for every packet that is successfully sent, a protobuf message is serialized to the file.