[PerfSuite-users] Re: PerfSuite problem - multiplexing not working?

[<rk...@nc...>]

Kursad,

Sorry to hear about the problems you're having but maybe we can
figure it out.  We have a similar setup at NCSA both on PIII and Xeon
systems and are using both PAPI 2 and 3 without problems.  As you
point out, cannot use PAPI 2 on the Pentium 4 system though.
It sounds to me like your PAPI install is fine.

I'll copy the SourceForge mailing list in case this might be of
interest to others.

There are a couple things I can think of to suggest:  first, are you
running psrun with a command that consumes a reasonable amount
of CPU time?  If not, you might get all zeroes due to the nature
of multiplexing (the counters may not have had sufficient time
to switch to actually collect counts).

If you are, then the next step is to configure PerfSuite with debugging
enabled (--enable-debug) and recompile.  That will cause a lot of tracing 
output to come (not what you'd want to use in production, but helpful
in seeing where things are getting out of line.  You'll also want
to set the environment variable PS_DEBUG to the value 3 or higher.

Also, you might try a run outside of psrun.  This is pretty simple
to do directly through the API.  You'll want to add the following
function calls (assuming you're using C/C++):

ps_hwpc_init();
ps_hwpc_start();
... do some computation here
ps_hwpc_stop("test");

One thing I should point out about the PerfSuite test suite is that
it has to be flexible enough to work regardless of the presence of
PAPI, so it's not as thorough as it could be.  That means the tests
of psrun may succeed when in fact the install is not quite right.

Let me know if any of these suggestions help - would like to get
you set up properly.

Rick

p.s. on the PIII with its two counters, what that means is that you
cannot use any "derived" events when multiplexing, because one counter
is always taken up for cycles, leaving only one left for other uses.

> ============ Kursad Albayraktaroglu's message of Jul  1,  8:41pm ================
> 
> We are trying to use Perfsuite 0.6.1b5 on a Linux/x86 machine, kernel
> version 2.4.22. We are using PAPI 3 (we're aware PAPI 3 support is alpha,
> but the unfortunate Linux kernel/GCC/PAPI combination that we have to use
> restricts us to this setup.)
> 
> All Perfsuite and PAPI tests during installation are completed
> successfully. When we run psrun with a configuration file that lists any
> of the two supported PAPI events, accurate event counts are reported.
> When more than two PAPI events are selected, we get zeros for all of
> them.
> 
> Figuring that this might have something to do with the 2 counter
> limitation of the Pentium 3 CPU on our system, we built the same software
> on a P4 system that has 18 counters. Same result : When more than 2 (not
> 18!) PAPI events are selected, all counts are reported as zero.
> 
> It would seem that multiplexing is not working, but we're perplexed about
> the situation on the P4 machine. Do you have any suggestions (short of
> switching to PAPI 2 which we can't do) or ideas on what we're doing wrong?
> 
> Regards,
> 
> --
> Kursad Albayraktaroglu
> 
> Ph.D. Candidate,
> Department of Electrical & Computer Engineering,
> University of Maryland, College Park
> 
> "Where ... the ENIAC is equipped with 18,000 vacuum tubes and weighs
> 30 tons, computers in the future may have 1,000 vacuum tubes and
> perhaps weigh just 1-1/2 tons."
> 
> 	Popular Mechanics, March 1949, p.258
> ============ End of Kursad Albayraktaroglu's message of Jul  1,  8:41pm =========