====== Xeon PHI HOWTO (for SPM1314 course) ======

===== Access =====
The machine with the Xeon PHI cards may be accessed using the IP address <code>131.114.137.225</code> and the credentials distributed during the lessons to the attending students. 

The credentials give access to a local account onto a Sandy Bridge multicore hosting the 2 PHI PCIe boards. 

In order to access the PHI, users should use an <code>ssh mic0</code> or <code>ssh mic1</code> command from the Sandy Bridge machine shell prompt. 

===== Set up environment =====
Before using the Intel tools you should setup the shell enviornment in such a way you can find all the right tools. You should use a <code>source /opt/intel/composer_xe_2013.1.117/bin/compilervars.sh intel64</code> command to this purpose. It is a good practice to append the command at the end of your home **.bashrc** file. 
===== Compiling ======
In order to produce executable programs for the PHI
  - the **icc** compiler **must** be used to compile the source code on the Sandy Bridge host, and
  - the **-mmic** flag should be specified

As an example, to compile the **prog.cpp** source code for the PHI we should use a command such as <code>icc -mmic prog.cpp -o prog</code>

===== Running ======
To run a program on the Xeon PHI: 
  * copy the program exceutable to the PHI home <code>scp prog mic0:</code> (You can use either mic0 or mic1 on this machine)
  * login to the PHI OS: <code>ssh mic0</code>(You should use the same **micXX** you used to copy) 
  * run the code: <code>./prog</code>and you'll see the results (**cout** writes) on the terminal
  * go back to the compiler shell<code>exit</code>

===== Running from remote =====
To run a program on the PHI without leaving the Sandy Bridge shell, consider using a couple of commands: 
  * first copy the program executable with a <code>scp progname micX:</code>
  * then run it from the current shell with a <code>ssh micX progname</code>
You can consider writing a small shell/perl script to automatize the process.