BEGIN:VCALENDAR PRODID:-//Microsoft Corporation//Outlook MIMEDIR//EN VERSION:1.0 BEGIN:VEVENT DTSTART:20121114T210000Z DTEND:20121114T213000Z LOCATION:155-E DESCRIPTION;ENCODING=QUOTED-PRINTABLE:ABSTRACT: As an entry for the 2012 Gorden Bell performance prize, we report=0Aperformance results of astrophysical N-body simulations of one=0Atrillion particles performed on the full system of K computer. This=0Ais the first gravitational trillion-body simulation in the world. =0AWe describe the scientific motivation, the=0Anumerical algorithm, the parallelization strategy, and the performance=0Aanalysis. Unlike many previous Gordon-Bell prize winners that used=0Athe tree algorithm for astrophysical N-body simulations, we used the=0Ahybrid TreePM method, for similar level of accuracy in which the short-range=0Aforce is calculated by the tree algorithm, and the long-range force is=0Asolved by the particle-mesh algorithm. We developed a highly-tuned=0Agravity kernel for short-range forces, and a novel communication=0Aalgorithm for long-range forces. The average performance on 24576 and=0A82944 nodes of K computer are 1.53 and 4.45 Pflops, which=0Acorrespond to 49% and 42% of the peak speed. SUMMARY:4.45 Pflops Astrophysical N-Body Simulation on K Computer - The Gravitational Trillion-Body Problem PRIORITY:3 END:VEVENT END:VCALENDAR BEGIN:VCALENDAR PRODID:-//Microsoft Corporation//Outlook MIMEDIR//EN VERSION:1.0 BEGIN:VEVENT DTSTART:20121114T210000Z DTEND:20121114T213000Z LOCATION:155-E DESCRIPTION;ENCODING=QUOTED-PRINTABLE:ABSTRACT: As an entry for the 2012 Gorden Bell performance prize, we report=0Aperformance results of astrophysical N-body simulations of one=0Atrillion particles performed on the full system of K computer. This=0Ais the first gravitational trillion-body simulation in the world. =0AWe describe the scientific motivation, the=0Anumerical algorithm, the parallelization strategy, and the performance=0Aanalysis. Unlike many previous Gordon-Bell prize winners that used=0Athe tree algorithm for astrophysical N-body simulations, we used the=0Ahybrid TreePM method, for similar level of accuracy in which the short-range=0Aforce is calculated by the tree algorithm, and the long-range force is=0Asolved by the particle-mesh algorithm. We developed a highly-tuned=0Agravity kernel for short-range forces, and a novel communication=0Aalgorithm for long-range forces. The average performance on 24576 and=0A82944 nodes of K computer are 1.53 and 4.45 Pflops, which=0Acorrespond to 49% and 42% of the peak speed. SUMMARY:4.45 Pflops Astrophysical N-Body Simulation on K Computer - The Gravitational Trillion-Body Problem PRIORITY:3 END:VEVENT END:VCALENDAR