> On May 26, 2016, 1:16 p.m., Curtis Dunham wrote: > > src/arch/x86/tlb.cc, line 128 > > <http://reviews.gem5.org/r/3474/diff/1/?file=55457#file55457line128> > > > > If this just (essentially) copy constructs a new TLB from the old, why > > can't the same TLB be used .. just reconnecting the SimObject graph? > > Presumably so some form of generality could in theory be applied, or this > > was more expedient?... > > Jason Lowe-Power wrote: > I think I see what you're saying, but I'm not sure how it would be done > with the current "takeOverFrom" API. Could you describe in more detail what > you're envisioning? > > From what I understand, when switching CPUs, each object's "takeOverFrom" > method is called with a pointer to the old version of the object. Do you > think this should be changed? > > Curtis Dunham wrote: > I'm not sure it should be changed, just calling it into question in this > case -- because what is this function doing that wouldn't have the same > result as just using the same TLB instance? I suspect it comes down to the > way the object graph is constructed, as a matter of gem5 philosophy, and how > that has been integrated with the "switcheroo" functionality. I'm not sure > it's worth opening that can of worms, unless we have a better solution. One > thing to consider though: generally speaking, would we want to do such a > copying when the std::type_info (return value of typeid(T)) for the two > objects is the same? Different hacker-speak terminology at the Python/SWIG > level, but same argument.
I guess it's possible that you would have a different TLB model for your detailed simulation vs. warmup. That would be a reason to use the "takeOverFrom" method instead of just switching the pointers or doing an automatic deep copy via type_info (if that's what you're proposing). Though that clearly isn't the case currently. Can we drop this issue for now? - Jason ----------------------------------------------------------- This is an automatically generated e-mail. To reply, visit: http://reviews.gem5.org/r/3474/#review8346 ----------------------------------------------------------- On May 20, 2016, 10:09 p.m., Jason Lowe-Power wrote: > > ----------------------------------------------------------- > This is an automatically generated e-mail. To reply, visit: > http://reviews.gem5.org/r/3474/ > ----------------------------------------------------------- > > (Updated May 20, 2016, 10:09 p.m.) > > > Review request for Default. > > > Repository: gem5 > > > Description > ------- > > Changeset 11482:51dec612f11b > --------------------------- > cpu, x86: Allow the TLB to be warmed up before CPU switch > > Previously, before a CPU was switched out, the TLB was always flushed > Now, we first call takeOverFrom with the TLB. We only flush > the TLB right before the CPU is switched in. > This changeset also contains the needed code for x86 to > takeOverFrom with the TLB, similar changes may be needed for the ARM > architecture. > With this changeset, when you switch from atomic to timing mode the > TLB is warm. > > > Diffs > ----- > > src/arch/x86/tlb.hh fc247b9c42b6 > src/arch/x86/tlb.cc fc247b9c42b6 > src/cpu/base.cc fc247b9c42b6 > > Diff: http://reviews.gem5.org/r/3474/diff/ > > > Testing > ------- > > > Thanks, > > Jason Lowe-Power > > _______________________________________________ gem5-dev mailing list [email protected] http://m5sim.org/mailman/listinfo/gem5-dev
