[parsec-users] Number of spawned threads.

Christian Bienia cbienia at CS.Princeton.EDU
Sun Apr 6 13:53:40 EDT 2008


Hi Krishna,

vips uses an environment variable to determine the number of threads to use. 
Look at the run.conf file in the parsec directory of the vips package. You 
will see the following line:

# VIPS expects the number of threads in an environment variable
export IM_CONCURRENCY=${NTHREADS}

You can verify that the correct number of threads is spawned with e.g. a 
profiling tool or the GNU debugger.

- Chris



On Sunday 06 April 2008 09:44 am, Krishna Rangan wrote:
> Hi Chris,
>
> Thanks, this works, except for the vips benchmark.  I dont really need to
> get all benchmarks going for my work, so this is not a problem.  Just
> letting you know.  But if this is supposed to work and I am launching the
> run incorrectly, please let me know.
>
> For the vips benchmark, the '-n nthreads' argument does not add or change
> any application qualifiers for any of the input sets.  That is, for any
> other value of '-n' below, the benchmark is launched with identical args.
>
> -- begin
>
> $ ./parsecmgmt -a run -c myconfig -p vips -i simlarge -n 8
> [PARSEC] Warning: At least bash version 3 is recommended. Earlier versions
> might not function properly. Current version is 2.05b.0(1)-release.
> [PARSEC] Benchmarks to run:  vips
>
> [PARSEC] [========== Running benchmark vips ==========]
> [PARSEC] Deleting old run directory.
> [PARSEC] Setting up run directory.
> [PARSEC] Unpacking benchmark input 'simlarge'.
> bigben_2662x5500.v
> [PARSEC] Running 'time
> ../pkgs/apps/vips/inst/i586-linux-linux.myconfig/bin/vips im_benchmark
> bigben_2662x5500.v output.v': [PARSEC] [---------- Beginning of output
> ----------]
> PARSEC Benchmark Suite Version 1.0
>
> real    0m13.568s
> user    0m21.250s
> sys     0m0.445s
> [PARSEC] [----------    End of output    ----------]
> [PARSEC] Done.
>
> -- end
>
> On Sat, 5 Apr 2008, Christian Bienia wrote:
> > Hello Krishna,
> >
> > You can specify the number of threads for all PARSEC programs at the
> > command line (or some other way at program start). The parsecmgmt tool
> > allows you do that in a convenient way. Several programs have to be run
> > with more threads than cores, the commercial workloads for example use a
> > number of threads equal to the number of cores for each pipeline stage
> > and depend on the scheduler to make the right decision. As a rule of
> > thumb, tell parsecmgmt that you want to run with N cores and everything
> > will be the way it should be.
> >
> > - Chris
> >
> > On Saturday 05 April 2008 03:11 pm, Krishna Rangan wrote:
> >> Hi,
> >>
> >> Is it possible to specify the number of threads spawed by the Parsec
> >> apps, either at compile time or during the application invocation?  Is
> >> it possible to do this for some if not all of the parsec apps, and for
> >> any of the small/medium/large input sets?
> >>
> >> I am studying a n-core architecture, and I am looking to create the same
> >> number of threads as the number of cores I am modeling.
> >>
> >> thanks,
> >> -krishna.
> >> _______________________________________________
> >> parsec-users mailing list
> >> parsec-users at lists.cs.princeton.edu
> >> https://lists.cs.princeton.edu/mailman/listinfo/parsec-users
> >
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> > parsec-users at lists.cs.princeton.edu
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