Hi Tod,
Great care has been taken to make the simulator itself deterministic. For
example, we always use the same seeds for random number generators, and avoid
iterating over unordered data structures. The even queue is gem5 is also
"stable" in that concurrent events will always be processed in the same order.
The decision to make it deterministic does, in my opinion, not make it less
realistic.
If you really want to shake things up, rather do so inside the simulated
system. Something we have found an easy solution is to add a variable amount of
sleep before you run your benchmark. This will give you the "run on a Tuesday
vs run on a Wednesday effect". I hope that answers your question.
Andreas
From: tod <[email protected]<mailto:[email protected]>>
Reply-To: gem5 users mailing list
<[email protected]<mailto:[email protected]>>
Date: Sunday, 23 June 2013 10:52
To: gem5-users <[email protected]<mailto:[email protected]>>
Subject: [gem5-users] Disk image with COW layer on Gem5: How to make a
simulation realistic?
Hello,
My simulation has been using
FS mode of Gem5
with the disk image "linux-arm-ael.img",
where my benchmark executes,
when the run-script.rcS is called.
To my observation, for the same inputs to a benchmark every execution leaves
the same traces.
With a multi-threaded application, even the printed 'my-thread-id' is same
every time.
Thread related information file 'system.task.txt' is also same for each
execution.
I am just wondering:
How far or close is this to the real system simulation?
Is this the CoW layer that is making it to produce same result every time?
But how about the underneath hardware (in this case Gem5),
shouldn't it behave randomly at every boot-up to at least
make a difference in the pattern of execution?
or If I am missing something?
Thank you for your reading. Any help will be greatly appreciated.
Best Regards,
tod
[http://wwl1482.hanmail.net:4280/@from=sarilian&rcpt=gem5%2Dusers%40gem5%2Eorg&msgid=%3C20130623185202%2EHM%2E0000000000000bB%40sarilian%2Ewwl1482%2Ehanmail%2Enet%3E]
-- IMPORTANT NOTICE: The contents of this email and any attachments are
confidential and may also be privileged. If you are not the intended recipient,
please notify the sender immediately and do not disclose the contents to any
other person, use it for any purpose, or store or copy the information in any
medium. Thank you.
_______________________________________________
gem5-users mailing list
[email protected]
http://m5sim.org/cgi-bin/mailman/listinfo/gem5-users
