Were is my "My Desktop" button

In order to get the "My Desktop" button back , e.g.on Windows Terminal servers, just execute the following command:

regsvr32 /n /i:U shell32

With the next reboot or upon restart of the Quick launch bar, the icon should appear.

Windows CCS Cluster Upgrade

Recently the Windows CCS Cluster of the RRZE got a small upgrade.

One of the initial nodes rejoined the cluster and there are now 28 Opteron Cores available again.
Due to the usage of CFD for production runs, the user home was recently upgraded and the quota was extended to 10 GB per user.
Furthermore for special purposes and a limited amount of time there is an extra project home available with up to 120 GB space for extensive usage.

PCI express revisited

Test results with the new generation, i.e. GT 200 based and PCIe Generation 2.0 with doubled performance, show that general naive implemented copys do not get any speedups.
Blocked copys however, climb up to 4.5 GB/s when writing data to GPU memory.
Data copy back to the host is still relatively low at 2 GB/s.





Link to first article

Fast Network, Fast disconnects (Linksys WRT610N )

Fast Network, Fast disconnects (Linksys WRT610N )
Looking forward to fast streaming HD Media over my new wireless router (WRT610N) I got into serious trouble on having a stable connection at all.

Having my network set up for WPA2 and TKIP for compatibility reasons, I got random disconnects of the whole 5 GHz band, while 2.4 GHz performed flawlessly. Searching the internet I stumbled across some serious accusations, that the WRT610N is a flawed design and overheats a lot.
Whether this is right or not I cannot say for sure, however I expected much more from Linksys and a home premium line product.

Searching a little more I came across another users experience that a change from the TKIP encryption to AES solved the problem of occuring disconnects.

And voila the problems seems to be solved.

So for everyone who can live with an AES only encryption on the 5 GHz 11N band and TKIP or AES on the 2.4 GHz 11g band the router is a perfect catch in both performance and appearance.

Yeehhaa: NVIDIA GT200 rocks

An exemplar of the new NVIDIA Series GT200 based GTX280 Graphics card arrived at our Computing Center last Friday . The card was installed and set up right away and the first benchmark ran on Saturday 22nd of November and finished today.

Some preliminary figures show the great improvement of this new generation as I expected from the data sheets. Soon I will post some verified results here and some about the changes from the G80 generation to the current GT200 chip.

Running MPI Jobs on Windows CCS

In order to run only one MPI process per allocated node on the Windows CCS Cluster, you have to tweak the system variable set by the scheduler. For each allocated processor the system variable (CCP_NODES) contains the associated hostname once.
As a consequence, four MPI processes are started.

In order to remove the redundant hostnames you call your program the following way from inside the scheduler:
mpiexec.exe -hosts %CCP_NODES: 4= 1%

%CCP_NODES: 4= 1% removes three out of four lines, which reduces each hostname down to one occurence, as the same hostnames are always consecutive.

Distributed Revision System Mercurial

Converting CVS to HG

To get hand on knowledge on the distributed revision systems like Mercurial,
just export one of your CVS Reps to a test HG Rep. Important for any repository, the history should stay intact (and hopefully will)!

A more complete guide can be found here:

Generate the repository folder and enter:
mkdir -p /path/to/hg/repo
cd /path/to/hg/repo

Generate the config file:

tailor -v --source-kind cvs --target-kind hg --repository /path/to/CVS/REP --module YourModuleName -r INITIAL >Config.tailor


for SSH access to the repository change /path/to/CVS/REP to :
:ext:USERNAME@YOURSERVER:/path/to/cvsrep


Change configfile to your needs
vi Config.tailor

Now you will at least need to change subdir from . to MODULENAME, and remove /MODULENAME from root-directory in the MODULENAME.tailor file (if it is really there).

Add the line:

patch-name-format =

Generate Mercurial project

tailor --configfile MODULENAME.tailor

Cloning repositories with ssh

To clone the repository, ssh can be used easily.
Just type the following hg clone ssh://yourlogin@yourhost/
or insert ssh://yourlogin@yourhost// in your client program as the source path.

Distributed Revision System Mercurial

Converting CVS to HG

To get hand on knowledge on the distributed revision systems like Mercurial,
just export one of your CVS Reps to a test HG Rep. Important for any repository, the history should stay intact (and hopefully will)!

A more complete guide can be found here:

Generate the repository folder and enter:
mkdir -p /path/to/hg/repo
cd /path/to/hg/repo

Generate the config file:

tailor -v --source-kind cvs --target-kind hg --repository /path/to/CVS/REP --module YourModuleName -r INITIAL >Config.tailor


for SSH access to the repository change /path/to/CVS/REP to :
:ext:USERNAME@YOURSERVER:/path/to/cvsrep


Change configfile to your needs
vi Config.tailor

Now you will at least need to change subdir from . to MODULENAME, and remove /MODULENAME from root-directory in the MODULENAME.tailor file (if it is really there).

Add the line:

patch-name-format =

Generate Mercurial project

tailor --configfile MODULENAME.tailor

Cloning repositories with ssh

To clone the repository, ssh can be used easily.
Just type the following hg clone ssh://yourlogin@yourhost/
or insert ssh://yourlogin@yourhost// in your client program as the source path.

Co-array Fortran and UPC

CAF and UPC are Fortran and C extensions for the Partitioned Global Adress Space (PGAS) model.
So independent of the hardware restrictions, each processor can access (read and write) data from other processors, without the need of additional communication libraries, e.g. MPI.

HLRS provided an introductory course about this.
At the current development stage I do not clearly see the benefit for production codes. However, some ideas might be implemented more quickly with these paradigms than with ordinary MPI for testing purposes.

Theses

• Johannes Habich: Performance Evaluation of Numeric Compute Kernels on NVIDIA GPUs, Master's Thesis , RRZE-Erlangen, LSS-Erlangen, 2008.


• Johannes Habich: Improving computational efficiency of Lattice Boltzmann methods on complex geometries , Bachelor's Thesis , RRZE-Erlangen, LSS-Erlangen, 2006.