I have now updated to the latest patch, and I am happy to report that
the variations have decreased significantly. Thank you very much for
your work there and for pointing it out to me.
The variation is still there, probably within an acceptable range, but I
would still like to try disabling interrupts just to see the effects as
it may be relevant for my work. Is there an easy way to do this (or
could you point me in the right direction)?
-Addison
On 02/16/2012 01:24 PM, avadh patel wrote:
On Thu, Feb 16, 2012 at 9:25 AM, Addison Mayberry
<[email protected] <mailto:[email protected]>> wrote:
Greetings,
I am continuing my mission to get repeatable performance out of
microbenchmarks in MARSS, and right now I'm looking at timer
interrupts as a possible culprit. To explain the situation a
little more, I'm running a microbenchmark that has a checkpoint
just before the interesting part. Upon reloading from the
checkpoint, the program drops into PTLsim and begins crunching
away, giving me periodic statistics dumps. These yield (sometimes
significantly) different results between runs, which I'm trying to
fix.
I'm running single_core, so as far as I understand from reading
some of Avadh's previous posts, the most likely culprits for this
problem are interrupts and I/O. Ignoring I/O for the moment, I'd
like to find a way to disable interrupts during the duration of my
microbenchmark. I've looked into doing it just using options on
the guest OS, but on my setup that would be pretty tricky. Would
it be possible to keep PTLsim from firing those timer interrupts?
I have pushed some bug fixes in latest 'features' branch. We are
testing these changes across different range of benchmarks. You can
pull the changes from github and help us to validate these changes.
Some people have reported that variation issues with many spec
benchmarks are now resolved. Please report back if your variation
issues are resolved.
- Avadh
Also, any thoughts or advice on the general non-determinism issue
would be appreciated. Thanks!
Sincerely,
Addison
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