Re: [Gems-users] Getting Multiprocessor benchmarks running on multiple processors at once

[Alaa Alameldeen <alaa@xxxxxxxxxxx>]

Sean,

Also make sure that Simics is switching between processors every cycle. If you 
are not sure, please run the following before starting Ruby/Opal:

conf.sim.cpu_switch_time = 1

-Alaa

Mike Marty wrote:
> I'm not sure what is going on.
>
> You chould check to see that this scheduling occurs without Opal to ensure
> that your trace code is correct and that Opal is not at fault.  You can
> dump out memory requests that enter the Ruby memory system by entering the
> following ruby commands in Simics:
>
>     ruby0.debug-output-file trace.txt
>     ruby0.debug-start-time "1"
>
>
>
>
> > 	I have modified opal to print out traces of all memory
> > instructions.  I call a function of the sequencer within the execute stage
> > of both memop objects.  This function prints out the following:
> >
> > m_local_cycles (which I am currently treating as the time)
> > the address of the instruction
> > whether it is a store
> > and the address being accessed.
> >
> > Each sequencer has its own file.
> >
> > When I merge these files, and sort them based on processor/sequencer I
> > observe that there are long strings in which only one processor accesses
> > the cache.  For instance, I start fmm -p4 (fast multipole method on four
> > processors from splash2), and do
> > c 1500000
> > to try to jump past some of the OS stuff.  I then load ruby and opal and
> > initialize them and run
> >
> > opal0.sim-step 5000000
> >
> > This produces several very large traces.  But sorting them and grouping
> > all adjacent memory accesses of the same processor as a single "string"
> > yields only 32 "strings", with an average length of 103,827 memory
> > accesses.  In other words, it appears that two threads are never executing
> > at the same time.  I get similar behavior from fft.  Does anyone have any
> > idea what I am doing wrong?
> >
> > - Sean