Re: [Gems-users] SMT in GEMS2.1

[Xuan Qi <xqi@xxxxxxxxxxx>]

Thanks Luke, could you help me with one more question:

I am simulating a system with 2 processor, each processor supports 2
threads. This is the configuration in my script, which basically follows
mfacet.py:

ruby0.setparam g_NUM_PROCESSORS 2
ruby0.setparam g_PROCS_PER_CHIP 2
ruby0.setparam g_NUM_SMT_THREADS 2
ruby0.setparam g_NUM_MEMORIES 1
ruby0.setparam g_MEMORY_SIZE_BYTES 536870912
ruby0.setparam NUMBER_OF_VIRTUAL_NETWORKS 6
ruby0.init
load-module opal
opal0.setparam CONFIG_LOGICAL_PER_PHY_PROC 2
opal0.setparam CONFIG_IREG_PHYSICAL 384
opal0.setparam CONFIG_FPREG_PHYSICAL 256
opal0.setparam CONFIG_CCREG_PHYSICAL 74
opal0.init

And I add this line in system.C just to check if the value of numProcs and
m_numSMTProcs is corret:
printf("numProcs[%d] numSMTProcs[%d]\n", numProcs, m_numSMTProcs);

The print out is:
numProcs[2] numSMTProcs[1]

If I understand your explanation correctly, numProcs should be 4 and
numSMTProcs should be 2 in this case. And my configuration apparently
didnt pass in the correct values. How should I set the parameters to make
the value correct? I tried to do: ruby0.setparam g_NUM_PROCESSORS 4, but
simics won't take it... Thank you.


Best regards,
Xuan Qi


On Tue, 25 Mar 2008, Luke Yen wrote:

>
> > If this is the case, the first assert should be:
> >
> > ASSERT( (cpuNumber >= 0) && (cpuNumber < system_t::inst->m_numSMTProcs) );
> >
> > instead of:
> >
> > ASSERT( (cpuNumber >= 0) && (cpuNumber < system_t::inst->m_numProcs) );
> >
> > Is it?
>
>     You can change it if you want, but in any case the error condition you
> care about will be caught by the assertion on seq_index, since the
> assignment makes seq_index get the value of cpuNumber.
>
> >
> > (2) in system.C
> >
> > first, the numProcs is defined as:
> >
> > // establish how many processors there are in the system
> >  int numProcs = SIM_number_processors();   //for SMT, this is the total
> > number of LOGICAL processors in the system
> >
> > then,
> >
> > m_numSMTProcs = numProcs / CONFIG_LOGICAL_PER_PHY_PROC;
> >
> > I am confused here because numProcs is first defined as the total number
> > of LOGICAL processors in the system. Is this the number of SMT processors?
> > If so, m_numSMTProcs = numProcs / CONFIG_LOGICAL_PER_PHY_PROC doesn't make
> > sense. It looks to me that numProcs should be set to the number
> > of PHYSICAL processors initiated by simics, is it? Maybe I misunderstand
> > the definition of LOGICAL processor?
> >
>
>     My definitions:
>       Logical = total number of HW thread contexts
>             (e.g. physical procs*(SMT contexts per proc), available to Simics for
>                   scheduling)
>       Physical = total number of physical procs (as seen by Ruby)
>
>     Luke
> _______________________________________________
> Gems-users mailing list
> Gems-users@xxxxxxxxxxx
> https://lists.cs.wisc.edu/mailman/listinfo/gems-users
> Use Google to search the GEMS Users mailing list by adding "site:https://lists.cs.wisc.edu/archive/gems-users/"; to your search.
>
>