Performability Aspects of the Atlas Vo; Using Lmbench Suite

The ATLAS Virtual Organization is grid's largest Virtual Organization which is currently in full production stage. Hereby a case is being made that a user working within that VO is going to face a wide spectrum of different systems, whose heterogeneity is enough to count as "orders of magnitude" according to a number of metrics; including integer/float operations, memory throughput (STREAM) and communication latencies. Furthermore, the spread of performance does not appear to follow any known distribution pattern, which is demonstrated in graphs produced during May 2007 measurements. It is implied that the current practice where either "all-WNs-are-equal" or, the alternative of SPEC-based rating used by LCG/EGEE is an oversimplification which is inappropriate and expensive from an operational point of view, therefore new techniques are needed for optimal grid resources allocation.Comment: 14 pages, 7 figures; Particular attention should be given to graph int64mul; A related presentation on the subject matter is available by the authors upon reques