Linux Scalability for Large NUMA Systems
The SGI Altix 3000 family of servers and superclusters are nonuniform memory access systems that support up to 64 Intel Itanium 2 processors and 512GB of main memory in a single Linux image. Altix is targeted to the high-performance computing (HPC) application domain. While this simplifies certain aspects of Linux scalability to such large processor counts, some unique problems have been overcome to reach the target of near-linear scalability of this system for HPC applications. In this paper we discuss the changes that were made to Linux 2.4.19 during the porting process and the scalability issues that were encountered. In addition, we discuss our approach to scaling Linux to more than 64 processors and we describe the challenges that remain in that arena.