This is a great find as we are also trying to find out some issues with checkpoints. I am not expert in QEMU so I have no idea what is restored when we continue execution from a checkpoint and do they modify and memory (like clock and some driver stats etc.). If you can share the method on how you collect your memory diffs then it will save lot of time in debugging.
Thanks, Avadh On Tue, Jan 10, 2012 at 10:01 AM, Addison Mayberry <[email protected]>wrote: > I've been using a tool called VBinDiff (visual binary diff), so I can see > exactly where the files are different. The differences are relatively > small, only a few hundred bytes concentrated in a few areas. However, since > I'm relatively sure that my performance variations are stemming from > differences in memory state I don't want to ignore anything that might be > causing those differences (and also I'm just curious as to what's > happening.) > > > On 01/10/2012 11:27 AM, Paul Rosenfeld wrote: > > I don't know the answer to your question, but this is certainly a very > interesting experiment. > > Are you doing "different or same" comparison or do you have some sense > of how different the memory dumps are? Are we talking a few bytes or large > swaths of memory? > > On Tue, Jan 10, 2012 at 11:10 AM, Addison Mayberry > <[email protected]>wrote: > >> Greetings, >> I am trying do some detailed performance tests, and to get more >> consistent data I have been trying to weed out issues that cause variation >> in my results on repeated executions of the same program from the same >> image checkpoint. To that end I started doing some analysis on the >> following two lines of code being executed in the simulator: >> >> ptlcall_checkpoint_and_shutdown("connection-made"); >> ptlcall_single_flush("-run"); >> >> After which my benchmark code begins to run. I added code in PTLSim to do >> a dump of simulated physical memory when it receives the "-run" >> instruction, and comparing these dumps across multiple runs I found that >> they were different. >> >> I was aware that MARSS is not guaranteed (or expected) to have >> deterministic performance, but I was surprised that there would be >> variations in the execution over such a small period of time - between >> loading the checkpoint and then dropping into simulation. Does anyone have >> any thoughts on what might be causing the differences in memory state, and >> what I might be able to do to keep that from happening and make my tests >> more repeatable? Thanks for any insight. >> Sincerely, >> Addison >> >> _______________________________________________ >> http://www.marss86.org >> Marss86-Devel mailing list >> [email protected] >> https://www.cs.binghamton.edu/mailman/listinfo/marss86-devel >> > > > > > _______________________________________________ > http://www.marss86.org > Marss86-Devel mailing list > [email protected] > https://www.cs.binghamton.edu/mailman/listinfo/marss86-devel > >
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