in earlier multiprocessor systems. For example, SCI is used as the basis for the NumaConnect technology. NUMA vs. cluster computing One can view NUMA as a tightly coupled form of cluster computing. The addition of virtual memory paging to a cluster architecture can allow the implementation of NUMA entirely in software. However, the inter-node latency of software-based NUMA remains several orders of magnitude greater (slower) than that of hardware-based NUMA. Software support Since NUMA largely influences memory access performance, certain software optimizations are needed to allow scheduling threads and processes close to their in-memory data. Microsoft Windows 7 and Windows Server 2008 R2 added support for NUMA architecture over 64 logical cores. Java 7 added support for NUMA-aware memory allocator and garbage collector. Linux kernel: Version 2.5 provided a basic NUMA support, which was further improved in subsequent kernel releases. Version 3.8 of the Linux kernel brought a new NUMA foundation that allowed development of more efficient NUMA policies in later kernel releases. Version 3.13 of the Linux kernel brought numerous policies that aim at putting a process near its memory, together with the handling of cases such as having memory pages shared between processes, or the use of transparent huge pages; new sysctl settings allow NUMA balancing to be enabled or disabled, as well as the configuration of various NUMA memory balancing parameters. OpenSolaris models NUMA architecture with lgroups. FreeBSD added support for NUMA architecture in version 9.0. Silicon Graphics IRIX (discontinued as of 2021) support for ccNUMA architecture over 1240 CPU with Origin server series. Hardware support As of 2011, ccNUMA systems are multiprocessor systems based on the AMD Opteron processor, which can be implemented without external logic, and the Intel Itanium processor, which requires the chipset to support NUMA. Examples of ccNUMA-enabled chipsets are the SGI Shub (Super hub), the Intel E8870, the HP sx2000 (used in the Integrity and Superdome servers), and those found in NEC Itanium-based systems. Earlier ccNUMA systems such as those from Silicon Graphics were based on MIPS processors and the DEC Alpha 21364 (EV7) processor. See also Uniform memory access (UMA) Cache-only memory architecture (COMA) HiperDispatch Partitioned global address space Nodal architecture Scratchpad memory (SPM) References External links NUMA FAQ Page-based distributed shared memory OpenSolaris NUMA Project Introduction video for the Alpha EV7 system architecture More videos related to EV7 systems: CPU, IO, etc NUMA optimization in Windows Applications NUMA Support in