> On Dec. 1, 2015, 5:31 p.m., Nilay Vaish wrote: > > src/cpu/o3/probe/elastic_trace.cc, lines 682-687 > > <http://reviews.gem5.org/r/3027/diff/3/?file=51963#file51963line682> > > > > Is this correct? Should not comp_delay = completionTick - > > executionTick . Secondly, the assert should be comparing the unsigned > > values as we discussed in another thread. > > Radhika Jagtap wrote: > Changing to assert per your suggestion. This is correct because the > completion_tick corresponds to inst A while execution_tick corresponds to > execute start tick of inst B that depends on A.
Clearly, I did not look close enough at the code. Anyways, now we should make comp_delay unsigned since comp_delay can overflow as the difference can be greater than 2^63-1. > On Dec. 1, 2015, 5:31 p.m., Nilay Vaish wrote: > > src/cpu/o3/probe/elastic_trace.cc, line 857 > > <http://reviews.gem5.org/r/3027/diff/3/?file=51963#file51963line857> > > > > Is the post decrement of any use? > > Radhika Jagtap wrote: > You are right, not used. Got rid of it. I can still see it. - Nilay ----------------------------------------------------------- This is an automatically generated e-mail. To reply, visit: http://reviews.gem5.org/r/3027/#review7656 ----------------------------------------------------------- On Dec. 3, 2015, 1:30 a.m., Curtis Dunham wrote: > > ----------------------------------------------------------- > This is an automatically generated e-mail. To reply, visit: > http://reviews.gem5.org/r/3027/ > ----------------------------------------------------------- > > (Updated Dec. 3, 2015, 1:30 a.m.) > > > Review request for Default. > > > Repository: gem5 > > > Description > ------- > > 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. > > > Diffs > ----- > > src/cpu/o3/probe/ElasticTrace.py PRE-CREATION > src/cpu/o3/probe/SConscript 135c16fa409d814dfbda979e59583534601dc1c7 > src/cpu/o3/probe/elastic_trace.hh PRE-CREATION > src/cpu/o3/probe/elastic_trace.cc PRE-CREATION > src/proto/SConscript 135c16fa409d814dfbda979e59583534601dc1c7 > src/proto/inst_dep_record.proto PRE-CREATION > src/proto/packet.proto 135c16fa409d814dfbda979e59583534601dc1c7 > > Diff: http://reviews.gem5.org/r/3027/diff/ > > > Testing > ------- > > > Thanks, > > Curtis Dunham > > _______________________________________________ gem5-dev mailing list [email protected] http://m5sim.org/mailman/listinfo/gem5-dev
