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


Date: Fri, 8 Jul 2005 17:00:12 -0500
From: "Min Xu (Hsu)" <xu@xxxxxxxxxxx>
Subject: Re: [Gems-users] Getting Multiprocessor benchmarks running on multiple processors at once
Sean,

This sounds strange to me. Can you provide more information, such as how do you
merge and sort your traces? What does a long string look like?

Thanks!

-Min

On Thu, 07 Jul 2005 Sean Ryan Leventhal wrote :
> 	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
> 
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