score-p.md

Score-P

Introduction

The Score-P measurement infrastructure is a highly scalable and easy-to-use tool suite for profiling, event tracing, and online analysis of HPC applications.

Score-P can be used as an instrumentation tool for Scalasca.

Installed versions

There are currently two versions of Score-P version 1.2.6 modules installed on Anselm :

• scorep/1.2.3-gcc-openmpi, for usage with GNU Compiler and OpenMPI
• scorep/1.2.3-icc-impi, for usage with Intel Compiler> and Intel MPI>.

Instrumentation

There are three ways to instrument your parallel applications in order to enable performance data collection:

1. Automated instrumentation using compiler
2. Manual instrumentation using API calls
3. Manual instrumentation using directives

Automated instrumentation

is the easiest method. Score-P will automatically add instrumentation to every routine entry and exit using compiler hooks, and will intercept MPI calls and OpenMP regions. This method might, however, produce a large number of data. If you want to focus on profiler a specific regions of your code, consider using the manual instrumentation methods. To use automated instrumentation, simply prepend scorep to your compilation command. For example, replace:

$ mpif90 -c foo.f90
$ mpif90 -c bar.f90
$ mpif90 -o myapp foo.o bar.o

with:

$ scorep  mpif90 -c foo.f90
$ scorep  mpif90 -c bar.f90
$ scorep  mpif90 -o myapp foo.o bar.o

Usually your program is compiled using a Makefile or similar script, so it advisable to add the scorep command to your definition of variables  CC, CXX, FCC etc.

It is important that scorep is prepended also to the linking command, in order to link with Score-P instrumentation libraries.

###Manual instrumentation using API calls

To use this kind of instrumentation, use scorep with switch --user. You will then mark regions to be instrumented by inserting API calls.

An example in C/C++ :

    #include <scorep/SCOREP_User.h>
    void foo()
    {
        SCOREP_USER_REGION_DEFINE( my_region_handle )
        // more declarations
        SCOREP_USER_REGION_BEGIN( my_region_handle, "foo", SCOREP_USER_REGION_TYPE_COMMON )
        // do something
        SCOREP_USER_REGION_END( my_region_handle )
    }

 and Fortran :

    #include "scorep/SCOREP_User.inc"
    subroutine foo
        SCOREP_USER_REGION_DEFINE( my_region_handle )
        ! more declarations
        SCOREP_USER_REGION_BEGIN( my_region_handle, "foo", SCOREP_USER_REGION_TYPE_COMMON )
        ! do something
        SCOREP_USER_REGION_END( my_region_handle )
    end subroutine foo

Please refer to the documentation for description of the API.

###Manual instrumentation using directives

This method uses POMP2 directives to mark regions to be instrumented. To use this method, use command scorep --pomp.

Example directives in C/C++ :

    void foo(...)
    {
        /* declarations */
        #pragma pomp inst begin(foo)
        ...
        if (<condition>)
        {
            #pragma pomp inst altend(foo)
            return;
        }
        ...
        #pragma pomp inst end(foo)
    }

and in Fortran :

    subroutine foo(...)
        !declarations
        !POMP$ INST BEGIN(foo)
        ...
        if (<condition>) then
     !POMP$ INST ALTEND(foo)
     return
     end if
     ...
     !POMP$ INST END(foo)
    end subroutine foo

The directives are ignored if the program is compiled without Score-P. Again, please refer to the documentation for a more elaborate description.