GRAPE-5: A Special-Purpose Computer for N-Body Simulations

[摘要] Wehavedevelopedaspecial-purposecomputerforgravitationalmany-bodysimulations,GRAPE-5.GRAPE-5acceleratestheforcecalculationwhichdominatesthecalculationcostofthesimulation.Allothercalculations,suchasthetimeintegrationoforbits,areperformedonageneral-purposecomputer(hostcomputer)connectedtoGRAPE-5.AGRAPE-5boardconsistsofeightcustompipelinechips(G5chip)anditspeakperformanceis38.4Gflops.GRAPE-5isthesuccessorofGRAPE-3.ThedifferencesbetweenGRAPE-5andGRAPE-3are:(1)ThenewlydevelopedG5chipcontainstwopipelinesoperatingat80MHz,whiletheGRAPEchip,whichwasusedforGRAPE-3,hadoneat20MHz.ThecalculationspeedofGRAPE-5is8-timesfasterthanthatofGRAPE-3.(2)TheGRAPE-5boardadoptedaPCIbusastheinterfacetothehostcomputerinsteadofVMEofGRAPE-3,resultinginacommunicationspeedoneorderofmagnitudefaster.(3)Inadditiontothepure1/rpotential,theG5chipcancalculateforceswitharbitrarycutofffunctions,sothatitcanbeappliedtotheEwaldorP3Mmethods.(4)ThepairwiseforcecalculatedonGRAPE-5isabout10-timesmoreaccuratethanthatonGRAPE-3.OnoneGRAPE-5board,onetimestepwithadirectsummationalgorithmtakes14(N/128k)2seconds.WiththeBarnes-Huttreealgorithm(θ=0.75),onetimestepcanbedonein15(N/106)seconds.

[学科分类] 天文学(综合)

[关键词] cosmology;"galaxy: kinematics and dynamics";"methods: numerical"