RE: grid computing

From: "Bachman, William" bachmanw@globomax.com Subject: RE: [NMusers] grid computing Date: 10/22/2003 1:31 PM Pete, In the case of multiple runs sent to a multiple-processor cluster, the speed-up factor is roughly inversely related to the number of processors in the cluster. From my AAPS poster presentation in Salt Lake City: Mathematical expressions for total run-time as a function of the number of runs in a batch and the number of processors in the cluster, where: P = no. of processors in the cluster (equal speed CPU's assumed) R = no. of run in the batch (equal individual run-times assumed) T(P,R) = total run-time as a function of P and R T1 = run-time for one run on one processor TO = network and software overhead time N = 1, 2, 3, ... (integer values) M = the number of integral multiples of runs compared to the number of processors = (R - modulus (R/P))/P For R>P and R is an integral N multiple of P: T(P,R) = N (T1 - T1/P) + TO For R< P: T(P,R) = (T1 - T1/R) + TO For R>P and R is not an integral multiple of P: T(P,R) = M (T1 - T1/P) + (T1 - T1/R) + TO As T1 increases, TO approaches 0 and is negligible for all but very fast runs. William J. Bachman, Ph.D. Manager, Pharmacometrics Research and Development GloboMax The Strategic Pharmaceutical Development Division of ICON plc 7250 Parkway Drive, Suite 430 Hanover, MD 21076 410-782-2212 bachmanw@globomax.com