Non-Uniform Memory Access


Non-Uniform Memory Access (NUMA) is a computer architecture design used in multiprocessor systems. It allows each processor to access both local memory (faster access) and remote memory (slower access) located near other processors. This architecture improves the performance and scalability of the system by reducing the memory access latency for processors retrieving data from their local memory.

Key Takeaways

  1. Non-Uniform Memory Access (NUMA) is a computer memory design used in multiprocessing systems where the memory access time depends on the memory location relative to a processor. In NUMA, a processor can access its local memory faster than non-local memory (memory connected to other processors).
  2. NUMA architecture helps in improving a system’s scalability, as it reduces the contention between processors for accessing memory by providing each processor with a dedicated memory block. This enables running multiple processors in parallel without significantly impacting their performance.
  3. NUMA is most effective in large-scale systems, such as data centers and high-performance computing clusters. It has become more important with the increase in multi-core processors since each core can act as a separate processing unit and benefit from reduced memory access latency.


Non-Uniform Memory Access (NUMA) is an important technology term because it directly impacts the performance and scalability of multi-processor systems.

NUMA is a computer memory design used in multiprocessor systems, where memory access time depends on the memory location relative to the processor.

This allows each processor in the system to access its local memory faster than the memory assigned to other processors, thus improving overall system performance.

In large-scale, data-intensive applications, NUMA is crucial for addressing latency issues and enabling efficient parallel processing.

By taking into account the non-uniform memory access times, the operating system and applications can optimize data access, improve performance, and maintain the balance between memory and compute resources.


Non-Uniform Memory Access (NUMA) is a technology designed to address the inherent performance limitations that arise within multi-processor systems. The key objective of NUMA is to improve the efficiency of memory utilization and processor communication in larger systems comprising multiple interconnected CPUs. In traditional shared memory configurations, all processors access memory through a single, shared bus.

However, as the number of processors increase, this bus becomes congested, leading to slower memory access speeds and consequently impacting the overall performance of the system. NUMA tackles this problem by dividing the system’s physical memory into several smaller local memory nodes, each directly connected to a particular processor. This decentralized approach allows each CPU to carry out its tasks without interfering with the memory operations of other processors, ensuring a balanced distribution of workload and a noticeable enhancement in system performance.

In a NUMA system, processors can still access memory nodes allocated to other CPUs — albeit at a slightly higher latency — fostering flexibility and adaptability within multi-processor environments. The primary advantage of using NUMA technology is that it facilitates seamless scalability as the number of processors increases, maintaining optimal performance levels even in massive parallel computing architectures. This technology has found considerable application in data centers, high-performance computing clusters, and large-scale enterprise servers, where maximizing efficiency, performance, and resource allocation is of paramount importance.

Key to implementing NUMA effectively is the use of clever scheduling algorithms: modern operating systems are designed to dynamically allocate tasks and resources to processors and memory nodes in an intelligent manner, considering the proximity of the involved components and the current system load, ensuring the most efficient utilization of the available resources.

Examples of Non-Uniform Memory Access

Non-Uniform Memory Access (NUMA) is a computer memory design used in multiprocessing systems, where the memory access time varies depending on where the data is located in relation to the processor. Here are three real-world examples of NUMA:

High-Performance Computing (HPC) Clusters: NUMA is often implemented in HPC clusters to improve performance. Large, complex scientific simulations and data analysis jobs require significant computational resources and memory. By implementing NUMA, these systems help to minimize the overhead and latency in inter-processor communication and memory access, thereby improving overall performance.

Virtualized Data Centers: In data centers that utilize hardware virtualization, such as VMWare or Hyper-V, virtual machines are hosted on physical servers with multiple processors. NUMA can be employed to improve the performance of virtual machines by ensuring that each VM is allocated memory that is local to the processor it is running on. This helps to reduce communication overhead between processors and memory and increases the efficiency of virtual machines.

Large-Scale Database Servers: Enterprise-level databases, such as Oracle, Microsoft SQL Server, and PostgreSQL, often run on large-scale server systems with multiple processors. NUMA allows these servers to maximize performance by ensuring that memory access times are kept as low as possible, particularly when processing large volumes of data and executing complex queries. By doing so, the database systems can provide faster performance and handle more concurrent users accessing the system.

Non-Uniform Memory Access (NUMA) FAQ

What is Non-Uniform Memory Access (NUMA)?

Non-Uniform Memory Access (NUMA) is a computer memory design used in multiprocessing systems in which the memory access time depends on the memory location relative to the processor. In a NUMA system, a processor can access its own local memory faster than non-local memory, or the memory of another processor.

Why is NUMA important?

NUMA is important because it enables efficient use of memory resources in systems with multiple processors. It allows for improved performance by enabling processors to access their local memory more quickly compared with non-local memory. This reduces the latency and contention for memory resources, leading to a better overall performance.

How does NUMA architecture work?

In a NUMA architecture, each processor has its own local memory and a memory controller. When a processor needs to access data, it first checks its local memory. If the required data is not available locally, the processor accesses the data from the memory of other processors. This non-local memory access takes longer than local access due to additional communication overhead.

What is the difference between NUMA and UMA (Uniform Memory Access)?

Uniform Memory Access (UMA) is a memory architecture where all processors in a multiprocessor system share the same memory with equal memory access time, regardless of the processor. In contrast, NUMA architecture features processors with their own local memory, where access time relies on the memory location relative to the processor. This results in faster access to local memory compared to non-local memory.

What are the benefits of using a NUMA architecture?

Some benefits of using a NUMA architecture include better memory access performance, increased system scalability, reduced memory contention, and improved parallel processing capabilities. NUMA can help distribute workloads more evenly across multiple processors, leading to more efficient processing and improved system performance.

Related Technology Terms

  • Memory Controller
  • Cache Coherency
  • Multi-Processor Architectures
  • Uniform Memory Access
  • Latency Optimization

Sources for More Information

  • IBM: The IBM website offers extensive information about Non-Uniform Memory Access technology, their applications and related products. Visit their homepage at
  • Intel Corporation: Intel is a leading technology company that has developed processors that support Non-Uniform Memory Access. Their homepage can be accessed at
  • Hewlett Packard Enterprise: HPE offers server solutions that utilize Non-Uniform Memory Access technology, providing valuable information and resources on their homepage at
  • Wikipedia: Wikipedia’s entry on Non-Uniform Memory Access provides a comprehensive overview of the technology and its application, along with numerous citations and references. The homepage can be found at

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