On Sat, Feb 6, 2010 at 12:22 PM, Steve Reinhardt <[email protected]> wrote: > On Sat, Feb 6, 2010 at 9:08 AM, soumyaroop roy <[email protected]> wrote: >> Let me rephrase my last question: >> Is there any way that a comparison could be performed between the >> checkpoint output by inorder with that output by a simple CPU? Say, if >> the number of committed instructions in both are the same when the >> checkpoints are dumped, should I expect that the register and memory >> state for both CPU's should be identical? > > I would expect so, as long as the inorder pipeline is drained and only > truly architectural state is checkpointed. Actually, earlier I was trying compare the same between O3 and simple-atomic and instead of paying attention to system.cpu.commit.commitCommittedInsts I was looking at system.cpu.commitInsts and that's why I wasn't seeing identical architectural register file contents between the two. Does that seem reasonable? The physical memory dumps are not identical though. Similar observations with inorder.
> >> >> In any case, what kind of testing strategy should be put in place to >> test the correctness of checkpointing apart from just taking >> checkpoints for programs/benchmarks, resuming from those checkpoints, >> running the programs till completion, and finally verifying the >> correctness of the outputs? > > We've had discussions on this before, though I don't recall all the > details of what we've come up with. Certainly the basic idea of > taking a checkpoint, restoring from that checkpoint, and then > comparing with an execution that didn't stop is a common one. You > wouldn't have to run all the way to the end; you could dump statistics > and perhaps another checkpoint at a common point further on but not > all the way at completion. There is an issue in that the drain > operation will perturb the state slightly, so you can't expect the > results to be identical unless you either (1) artificially induce a > drain without a checkpoint at the same spot in the non-checkpointed > execution or (2) do a stats reset at a common point in both > simulations after the checkpoint restore. The latter seems a lot > simpler to me. Thanks, I will try this. Is there an option in any of the scripts to reset stats at an instruction? > > Steve > _______________________________________________ > m5-dev mailing list > [email protected] > http://m5sim.org/mailman/listinfo/m5-dev > -- Soumyaroop Roy Ph.D. Candidate Department of Computer Science and Engineering University of South Florida, Tampa http://www.csee.usf.edu/~sroy _______________________________________________ m5-dev mailing list [email protected] http://m5sim.org/mailman/listinfo/m5-dev
