Merge pull request #2 from PDC-support/thor/mixed-updates

small updates

README.md

@@ -22,7 +22,35 @@ The Cray automatically loads several [modules](https://www.pdc.kth.se/support/do
 - Heimdal - [Kerberos commands](https://www.pdc.kth.se/support/documents/login/login.html#general-information-about-kerberos)
 - OpenAFS - [AFS commands](https://www.pdc.kth.se/support/documents/data_management/afs.html)
 - SLURM -  [batch jobs](https://www.pdc.kth.se/support/documents/run_jobs/queueing_jobs.html) and [interactive jobs](https://www.pdc.kth.se/support/documents/run_jobs/run_interactively.html)
+- Programming environment - [Compilers for software development](https://www.pdc.kth.se/support/documents/software_development/development.html)
 
+# Compiling MPI programs on Beskow
+
+By default the cray compiler is loaded into your environment. In order to use another compiler you have to swap compiler modules:
+
+```
+module swap PrgEnv-cray PrgEnv-gnu
+```
+or
+```
+module swap PrgEnv-cray PrgEnv-intel
+```
+
+On Beskow one should always use the *compiler wrappers* `cc`, `CC` or 
+`ftn` (for C, C++ and Fortran codes, respectively), 
+which will automatically link to MPI libraries and linear 
+algebra libraries like BLAS, LAPACK, etc.
+
+Examples:
+
+```
+# Fortran
+ftn [flags] source.f90
+# C
+cc [flags] source.c
+# C++
+CC [flags] source.cpp
+```
 
 # Running MPI programs on Beskow
 
@@ -32,6 +60,9 @@ First it is necessary to book a node for interactive use:
 salloc -A <allocation-name> -N 1 -t 1:0:0
 ```
 
+You might also need to specify a reservation by adding the flag 
+`--reservation=<name-of-reservation>`.
+
 Then the srun command is used to launch an MPI application:
 
 ```

lab1/README.md

@@ -28,7 +28,8 @@ which will help you get going on Beskow.
 
 # Exercise 1: Run "Hello, World"
 
-Run the "Hello, World" program found in the lecture. Make sure you understand how each processors prints its rank as well as the total number of processors in the communicator MPI_COMM_WORLD.
+[Compile](https://www.pdc.kth.se/support/documents/software_development/development.html) 
+and run the "Hello, World" program found in the lecture. Make sure you understand how each processors prints its rank as well as the total number of processors in the communicator MPI_COMM_WORLD.
 
 
 # Exercise 2: Send data across all processes