Headless installation of virtualgl.

After installation of virtualgl on CentOS 6.2 one need to be sure that main X.org is starting without monitor.
Without that the vglrun throws an error unable to connect to display :0
The reason is xorg is not started due to the monitor. The monitor is detached.
You cannot keep one monitor per cluster node if you want to run rendering farm of 1000 GPUs.
So the solution is to run nvidia driver in headless mode!!!
After Nvidia official driver installation run following:

 
nvidia-xconfig -a --use-display-device=None --virtual=1280x1024

reboot it.
Then the in the vnc connection simply run:

vglrun glxinfo| grep -i renderer 

You should see your GPU string information: in my case is Tesla 2050

CentOS 6.2 unable to update using yum!!!

The CentOS 6.2 was unable to update using yum due to failure on system, I did accidentally reboot during the update process.  Then I discovered that yum unable to update with following error:

... Many errors and some concerning glibc

You could try using --skip-broken to work around the problem

It does not help it was claiming that:
glibc is protected_multilib
To fix:

yum clean all

package-cleanup  --cleandupes


yum check-update

yum update --setopt=protected_multilib=false --skip-broken

WiFi Scanning on Ubunty? Its soo easy!!!

In order to scan documents on Ubunty 12.04 you should install:
I have a Epson Wifi SX425w printer. On Epsons web site I was able to find debian package for the drivers. Using dpk I installed them.
Next step:
Install XSane Image Scanner.
run Xsane anad enjoy it!
Ubuntu 12.04 rocks (besides on many troubles on my Sony laptop) 

Ubuntu 12.04 desktop trouble it is empty.

After messing up the compiz setting the desktop was empty. In order to fix it one should press: Ctrl+Alt+F1 to get terminal then in terminal run:
bash~# unity --reset
It will bring the default unity configuration.
And Enjoy Ubunty 12.04LTE!!!

 

in order to run virtual machine on linux use this:


/usr/libexec/qemu-kvm -hda AN-cloud1.qcow -hdb an-cloud1-srv.qcow -boot c -cpu host -smp 2 -m 2048 -net nic,macaddr=DE:AD:BE:EF:FD:A2 -net user,hostfwd=tcp::20022-:22,hostfwd=tcp::20080-:80,hostfwd=tcp::20033-:3306 -vnc :9 -usbdevice tablet

How to swap integers without using third variable?

The solution is simple:
a=a|b;
b=a^b
a=a^b

stl::map vs boost::multi_index

Well, what is the best way to simulate 3 column database table using c++?
I am trying to use the Boost.multiindex container for my particle tracking project.
The first problem what I was accounting is the set_intersection. The data table is following:

struct particleID
 {
 int           ID;// real ID for particle from Gadget2 file "ID" block
 unsigned int  IDf;// postition in the file
 particleID(int id,const unsigned int idf):ID(id),IDf(idf){}
 bool operator<(const particleID& p)const { return ID<p.ID;}
 unsigned int getByGasID()const {return (ID&0x0FFF);};
 friend std::ostream & operator <<(std::ostream& , const particleID& p );
 };

The multiset container is configured as following:

struct ID{};
struct IDf{};
struct IDgas{};

typedef multi_index_container<
 particleID,
 indexed_by<
  ordered_unique<
   tag<IDf>,  BOOST_MULTI_INDEX_MEMBER(particleID,unsigned int,IDf)>,
  ordered_non_unique<
   tag,BOOST_MULTI_INDEX_MEMBER(particleID,int,ID)>,
  ordered_non_unique<
   tag,BOOST_MULTI_INDEX_CONST_MEM_FUN(particleID,unsigned int,getByGasID)> 
 >
> particlesID_set;

So I will continue it in my next post, while I am going to watch nice movie by "ARTE" channel.