= OpenCL Notes =
== Disable auto vectorization ==
In the section 6.7.2 (187 page) in the OpenCL Specification Version: 1.1 (Revision: 33), "__attribute__((vec_type_hint(<typen>))" is described. This hint controls the autovectorizer in the compiler for OpenCL C. I tested this feature by dumping the assembly code for a kernel targeted for AVX instructions with Intel SDK (version 1.5).

||               || lines || performance ||
|| no hint       || 1567  ||             ||
|| with the hint || 333   ||             ||

This hint amazingly reduces the size of the generated kernel code! Cool. 

== SDK and driver == 

== Latest SDK ==
AMD http://developer.amd.com/gpu/ATIStreamSDK/Pages/default.aspx

Intel http://software.intel.com/en-us/articles/vcsource-tools-opencl-sdk/

Nvidia 

Apple'SDK comes with MacOS X only

== Latest Driver for AMD ==
http://support.amd.com/us/gpudownload/linux/Pages/radeon_linux.aspx?type=2.4.1&product=2.4.1.3.42&lang=English


= old info =
== Standard Compute Layer Library ==
http://www.browndeertechnology.com/stdcl.html

A wrapper library API for OpenCL API used in the tutorial below.
It seems that the libstdcl greatly simplify 
a sample program ($OPENCLDIR/samples/opencl/cl/app/NBody) supplied with Stream SDK 2.0beta.

== OpenCL Tutorial: N-Body Simulation == 
http://www.browndeertechnology.com/docs/BDT_OpenCL_Tutorial_NBody.html

A tutorial that modifies the sample NBody program written in OpenCL API.

== local & global ==
http://forums.amd.com/devforum/messageview.cfm?catid=390&threadid=123350&enterthread=y
{{{
It's a tricky question . On 4xxx __local mem is really __global mem ( ATI thinks it's too much work to optimize compiler to use 48xx  LDS - although it's possible ). 
On 5xxx __local is LDS - so it's located in simd core.
}}}


== Catalyst 10.1 with Ubuntu 9.10 workarounds ==
=== Change the kernel boot option ===
Edit "/etc/default/grub" and execute update-grub. I add "nopat" to GRUB_CMDLINE_LINUX_DEFAULT for Catalyst 10.1.

The configuration file for the grub is at /boot/grub/grub.cfg.
This file is automatically generated by update-grub command.

This trick is not necessary for Catalyst 10.2.

=== X server setting ===
The default login manager gdm is difficult to properly configure, I install xdm instead of gdm.
The configuration file for xdm is at /etc/X11/xdm directory.

Edit "Xservers" file as
{{{
:0 local /usr/bin/X :0 vt7 -nolisten tcp -ac
}}}
This "-ac" option enable remote applications to access the local X server.
Note this option is generally regarded as "bad" for security. Be careful.

= Random notes =
== icc ==
http://software.intel.com/en-us/articles/using-intel-compilers-for-linux-with-ubuntu/

== packages ==
Ubuntu 10.04.1 LTS
{{{
sudo aptitude install libgsl0-dev gfortran libnetcdf-dev linux-headers-2.6.32-22-generic g++ libblas-dev rake emacs lv zsh ssh xdm ia32-libs  linux-image-2.6.32-22-generic subversion git-core  openmpi-bin openmpi-dev 
}}}

10.04 LTS Server
{{{
sudo aptitude install xdm ia32-libs subversion zsh libgsl0-dev gfortran libnetcdf-dev g++  freeglut3-dev xserver-xorg rake emacs lv xterm 
}}}


http://forums.amd.com/devforum/messageview.cfm?catid=390&threadid=147002

== process affinity ==
From command line: http://www.cyberciti.biz/tips/setting-processor-affinity-certain-task-or-process.html

http://www.open-mpi.org/projects/hwloc/

== DOUBLE ==
http://developer.amd.com/support/KnowledgeBase/Lists/KnowledgeBase/DispForm.aspx?ID=92