<body bgcolor="#ffffff" background="https://img.web.de/v/p.gif" class="bgRepeatYes" style="background-repeat: repeat; ; background-color: rgb(255, 255, 255); color: rgb(0, 0, 0); font-family: verdana,geneva; font-size: 9pt; padding-left: 0px;"><div style="min-height: 200px; background-image: url(https://img.web.de/v/p.gif); background-repeat: repeat; background-color: #ffffff; font-family: verdana,geneva; font-size: 9pt; padding-left: 0px;"><span style="font-size: 9pt;"><span style="font-family: verdana,geneva;"><span style="background-color: transparent;"><span style="color: #000000;"><span style="color: #000000;"> Hello,<br /><br />my name is Norman, and i administrate a 32x FSC Primergy-Cluster installed with OpenSuse, SunGridEngine, MPICH and linked with Gigabit-Ethernet. Its used for executing scientific scripts on a cpmd.x or sander.mpi with a input file of atoms. If i run such a job on one machine=4cpus, it runs with nearly 100 %. BUt if i now run the same job on 8 cpus=2 machines, the average goes down to close under 50 %. Means one machine alone is faster than 2 machines. But i think the sense of a cluster is to bundle the cpu-power, or not?? Am I right when i suppose that mpi does only work when the programmer himself splitt the tasks in his programm or script with MPI-Commands?<br /><br />It complicated =)! Or could it be that while compiling a programm for example the normal routines, operators and functions are replaced with mpi-functions which have the communication routines within, so that the comiled programm example.x can itself can communicate??? But if, how the program know with which machine it shell cooperate.<br /><br />Firstly i though that maybe the job isn't cooperating but executed on f.e. two machines seperately, but the output files are normal, no dublicates or something.<br /><br />Please help me to understand the real mechanics of mpich so i can try to optimze my cluster to execute jobs on multible machines with a good average.<br /><br />Thank you very much.<br /></span></span></span></span></span></div> <br><br><table cellpadding="0" cellspacing="0" border="0"><tr><td bgcolor="#000000"><img src="https://img.web.de/p.gif" width="1" height="1" border="0" alt="" /></td></tr><tr><td style="font-family:verdana; font-size:12px; line-height:17px;">WEB.DE DSL ab 19,99 Euro/Monat. Bis zu 150,- Euro Startguthaben und <br>50,- Euro Geldprämie inklusive! https://freundschaftswerbung.web.de</td></tr></table>
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