[parsec-users] PARSEC on Simics

Christian Bienia cbienia at CS.Princeton.EDU
Thu Sep 11 14:31:25 EDT 2008


I doubt that 100M instructions are sufficient to get accurate results with
most PARSEC workloads. From the list you gave it seems that workloads that
have only one kernel (i.e. almost all the time is spent in only one loop)
give you accurate results, whereas workloads with multiple kernels don't.
Most likely that's because 100M instructions is not sufficient to make it
through all kernels. This can have a high impact on the characteristics of
the program.

To simulate these workloads accurately, you have to switch between accurate
simulation and fast-forward mode so that every kernel is executed at some
point. You also need to make sure that the kernels are weighted like in the
real program.

- Chris

-----Original Message-----
From: parsec-users-bounces at lists.cs.princeton.edu
[mailto:parsec-users-bounces at lists.cs.princeton.edu] On Behalf Of
jlira at ac.upc.edu
Sent: Thursday, September 11, 2008 2:16 PM
To: PARSEC Users
Subject: [parsec-users] PARSEC on Simics

Hi all,

I use Simics+GEMS for simulating PARSEC workloads, and I am facing some
unrealistic results on some of them. The key thing is that I am unable to
the whole program, so I simulate a part of each of them.

I start my simulations on the beginning of the ROI and execute a piece of
of instructions. Although some of the workloads give excellent results
(blackscholes, canneal, dedup and swaptions), there are other in which the
number of instructions executed in user mode are ridiculous (I guess because
some kind of synchronization in the program) (bodytrack, facesim,
freqmine, streamcluster and x264). Thus, resulting statistics can not be
realistic because no program code have been executed.

I suppose that some of you use Simics or Simic+GEMS like me, and may help me
sharing your expirience on that simulators executing the "problematic"
workloads. I also accept advises about methodology that can help me on this

Many thanks to all in advance for your help,

Javier Lira

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