Nonuniform memory architecture distributed operating systems distributed operating systems types of distributed computes multiprocessors memory architecture nonuniform memory architecture threads and multiprocessors multicomputers network io remote procedure calls distributed systems distributed file systems 6 42 linux supports multiple. Non uniform memory access or non uniform memory architecture numa is a computer memory design used in multiprocessors, where the memory access time depends on the memory location relative to a processor. Physically centralized memory, uniform memory access uma all memory is allocated at same distance from all processors also called symmetric multiprocessors smp memory bandwidth is fixed and must accommodate all processors does not. Shared memory multiprocessors issues for shared memory systems. Processor scheduling and page placement schemes, dominant factors of memory access overhead, are closely related. A memory architecture, used in multiprocessors, where the access time depends on the memory location. Numa multiprocessors numa machines 3 key characteristics. We call the problem of assigning parallel processes of an application to processors application placement. Mem cpu cpu cpu cpu cache mem cache mem cache mem cache rarer and more expensive can have 16, 64, 256 cpus. A case for uniform memory access multiprocessors acm. Such organization is called nonuniform memory access, or numa. By using a combination of the hierarchical bus implementations and the crosspoint cache architecture, it should be feasible to construct shared memory multiprocessor systems with several hundred processors.
Latency hiding on coma multiprocessors springerlink. Us6289424b1 method, system and computer program product. The nodes are partitioned into external interrupt domains so that an external interrupt is always presented to a processor within the external interrupt domain in which the interrupt occurs. According to physical organization of processors and memory. Parallel processing and multiprocessors why parallel.
Memory management for largescale numa nonuniform memory access multiprocessors thomas j. A smp is a system architecture in which all the processors can access each memory block in the same amount of time. Memory management for largescale numa nonuniform memory. A computer system in which two or more cpus share full access to a common ram 4 multiprocessor. A template library to integrate thread scheduling and. The two basic types of shared memory architectures are uniform memory access uma and nonuniform memory access numa, as. Virtually all the shared memory architectures that have appeared in recent times are of the numa non uniform memory access type.
Carla schlatter ellis, supervisor herbert crovitz mark holliday donald loveland robert wagner an abstract of a dissertation submitted in partial fulfillment of the requirements for the degree. Characteristic features of the numa non uniform memory access architecture. Coma organization in traditional numa multiprocessors, each node contains one or more processors with private caches and a memory module that is part of the global shared. There is a single address visible to all cpus access to remote memory is via load and store instructions access to remote memory is slower than access to local memory ncnuma no caching access time to remote memory is not hidden cc. Bus and cache memory organizations for multiprocessors by donald charles winsor chairman. The thesis of this paper is that scheduling decisions in largescale, sharedmemory, numa nonuniform memory access multiprocessors must consider not only how many processors, but also which processors to allocate to each application. Under numa, a processor can access its own local memory faster than nonlocal memory, that is, memory local to another processor or memory. Physically centralized memory, uniform memory access uma all memory is allocated at same distance from all processors also called symmetric multiprocessors smp memory bandwidth is fixed and must accommodate all. Carla schlatter ellis, supervisor herbert crovitz mark holliday donald loveland robert wagner an abstract of a dissertation submitted in partial fulfillment of the requirements for the.
Nonuniform memory access numa is a computer memory design used in multiprocessing, where the memory access time depends on the memory location. Uniform memory access uma is a shared memory architecture used in parallel computers. A processor can access its own local memory faster. Two variations of sharedeverything architecture are symmetric multiprocessing smp and distributed shared memory dsm. Numa non uniform memory access is a method of configuring a cluster of microprocessor in a multiprocessing system so that they can share memory locally, improving performance and the ability of the system to be expanded. All the processors have equal access time to all the memory words. Uma using busbased symmetric multiprocessing smp architectures uma using crossbar. Cache coherence and synchronization tutorialspoint. Non uniform memory access numa is a computer memory design used in multiprocessing, where the memory access time depends on the memory location relative to the processor. This work explores the possibility of using speculation at the directories in a cache coherent non uniform memory access multiprocessor architecture to improve performance by forwarding data to their destinations before requests are sent. Nonuniform memory access or nonuniform memory architecture numa is a computer memory design used in multiprocessors, where the memory access time depends on the memory location relative to a processor. Difference between uniform memory access uma and non. Memory subsystem optimization techniques for modern highperformance generalpurpose processors. Why this difference exists will become clear later.
Were upgrading the acm dl, and would like your input. Uniform memory access uma, nonuniform memory access numa, and no remote memory access norma. On the importance of parallel application placement in. Numa, or nonuniform memory access, is a shared memory architecture that.
These machines are called uma uniform memory access multiprocessors. Distributed operating systems distributed operating systems types of distributed computes multiprocessors memory architecture nonuniform memory architecture threads and multiprocessors multicomputers network io remote procedure calls distributed systems distributed file systems 5 42 primarily shared memory lowlatency. Find out information about nonuniform memory access. In a uma multiprocessor the shared memory is global to all processors. Cse 5 introduction to operating systems class 9 distributed and. Pdf memory management for largescale numa nonuniform.
Parallel computer architecture models tutorialspoint. Download fulltext pdf load balancing for parallel query execution on numa multiprocessors article pdf available in distributed and parallel databases 71. Uniform memory access multiprocessor, a numa machine has a single. Cacheonly memory access coma multiprocessors support scalable coherent shared memory with a uniform memory access programming model. For nonuniform memory access numa multiprocessors, memory access overhead is crucial to system performance. A centralized memory that is uniformly accessible by all the nodes. The two basic types of shared memory architectures are uniform memory access uma and non uniform memory access numa, as shown in fig. Reducing hotspot contention in shared memory multiprocessor. In contrast, numa nonuniform memory access multiprocessors do not have this property. There is a single address space visible to all cpus. Nonuniform memory access multiprocessors should provide traditional virtual memory. Latencyhiding mechanisms can reduce effective remote.
Distributed shared memory powerpoint presentation free to download id. Many multicore multiprocessors have a nonuniform memory architecture. Thus, some memory locations are closer to a processor and less expensive to access than others resulting in a non uniform memory access cost. Numa nonuniform memory access since memory is physically distributed, it is faster for a processor to access its own local memory than nonlocal memory memory local to another processor or shared between processors. For optimal performance, the kernel needs to be aware of where memory is located, and keep memory used as close as possible to the user of the memory.
Latencyhiding mechanisms can reduce effective remote memory access latency by. Speculative data distribution in shared memory multiprocessors. Memory subsystem optimization techniques for modern high. Uniform memory access uma uniform memory access uma architecture means the shared memory is the same for all processors in the system. More recently, shared memory multiprocessors followed some trends previously established for multicomputers. Uniform memory access uma, nonuniform memory access numa, and. Uma multiprocessors using multistage switching networks can be built from 2. Performance analysis of uma and numa models citeseerx. Coherence controller architectures for smpbased ccnuma multiprocessors. More recently, sharedmemory multiprocessors followed some trends previously established for multicomputers. Abstract computer science page placement for nonuniform memory access time numa shared memory multiprocessors by richard p. Unlike smps, all processors are not equally close to all memory locations.
All the processors in uma model share the physical memory uniformly. A nonuniform memory access numa computer system includes at least two nodes coupled by a node interconnect, where at least one of the nodes includes a processor for servicing interrupts. Parallel processing and multiprocessors why parallel processing. This cachebased organization of memory results in long remote memory access latencies. In an uma architecture, access time to a memory location is independent of which processor makes the request or which memory chip contains the transferred data. Operating systems multiple processor systems multiple processor. Popular classes of uma machines, which are commonly used for file servers, are the socalled symmetric multiprocessors smps. A template library to integrate thread scheduling and locality management for numa multiprocessors. Main memory cache cache cache cache all main memory takes the same time to access scales only to 4, 8 processors. Department of computer science duke university date. Cse 5 introduction to operating systems class 9 distributed and multiprocessor operating systems. Uniform memory access uma in this model, all the processors share the physical memory uniformly. Page placement for nonuniform memory access time numa.
Multiprocessors can be categorized into three shared memory model which are uniform memory access uma non uniform memory access numa cacheonly memory access coma uniform memory access uma. Numa and uma and shared memory multiprocessors computer. Shared memory multiprocessors 1 cis 501 introduction to computer architecture unit 11. Nonuniform memory access numa shared memory multiprocessors all memory can be addressed by all processors, but access to a processors own local memory is faster than access to another processors remote memory looks like a distributed machine, but interconnection network is usually customdesigned switches andor buses.
Harder to program, but scales to more processors bus based uma a simplest mp. Nonuniform memory access numa numa architectures support higher aggregate bandwidth to memory than uma architectures tradeoff is nonuniform memory access can numa effects be observed. Nonuniform memory access article about nonuniform memory. Although all multiprocessors have the property that every cpu can address all of memory, some.
More than one processor on a single bus connect to memory, bus bandwidth becomes a bottleneck. Different solutions for smps and mpps cis 501martinroth. Nonuniform memory access numa college of computing. From a hardware perspective, a shared memory parallel architecture is a computer that has a common physical memory accessible to a number of physical processors. Find out information about non uniform memory access. This capability is often referred to as uma or uniform memory access. Three most common shared memory multiprocessors models are. Many multicore multiprocessors have a non uniform memory architecture numa, and for good performance, data and computations must be partitioned so that ideally all threads execute on the processor that holds their data. All the processors in the uma model share the physical memory uniformly. Download as ppt, pdf, txt or read online from scribd.
Template library to integrate thread scheduling and locality management for numa multiprocessors. Ppt introduction to parallel processing powerpoint. The thesis of this paper is that scheduling decisions in largescale, sharedmemory, numa non uniform memory access multiprocessors must consider not only how many processors, but also which processors to allocate to each application. Memory management for largescale numa nonuniform memory access multiprocessors. Numa multiprocessors q single address space visible to all cpus q access to. Shared memory multiprocessors 14 an example execution. The local portion of shared memory associated with a processor is organized as a cache. Also referred to as symmetric memory processors smps. Cpus share full access to a common ram multiprocessor system two types of multiprocessor systems uniform memory access uma all memory addresses are reachable as fast as any other address nonuniform memory access numa some memory addresses are slower than others.
Lecture overview multiple processors multiprocessors uma versus numa. Trevor mudge the single shared bus multiprocessorhas been the most commerciallysuccessful multiprocessorsystem design up to this time, largely because it permits the implementation of ef. It is not scalable because memory access time includes the latency of the interconnection network, and this latency increases with system size. This architecture is referred to as uniform memory access uma architecture. Numa multiprocessors shared memory one logical address space can be treated as shared memory use synchronization e. Nonuniform memory access numa is a computer memory design used in multiprocessing, where the memory access time depends on the memory location relative to the processor. Multiprocessors a sharedmemory multiprocessor is a computer system composed of multiple independent processors that execute different. In a uma multiprocessor the shared memory is global to. Research feature cacheonly memory research feature. Pdf load balancing for parallel query execution on numa. Numa nonuniform memory access access to some parts of memory is faster for some processors than other parts of memory. Support for diverse architectures, including multiprocessors with varying degrees of shared memory access. Shared memory multiprocessors are differentiated by the relative time to access the common memory blocks by their processors.
This work explores the possibility of using speculation at the directories in a cache coherent nonuniform memory access multiprocessor architecture to improve performance by forwarding data to their destinations before requests are sent. Large count multiprocessors are being built with nonuniform memory access numa times access times that are dependent upon where within the machine a piece of memory physically resides. The adobe flash plugin is needed to view this content. We first see the existing multiprocessor architectures and what changes numa demands memory access architecture. Us6148361a interrupt architecture for a nonuniform. Virtually all the sharedmemory architectures that have appeared in recent times are of the numa nonuniform memory access type. For non uniform memory access numa multiprocessors, memory access overhead is crucial to system performance. Numa, or non uniform memory access, is a shared memory architecture that. On the importance of parallel application placement in numa. Method, system and computer program product for managing memory in a nonuniform memory access system download pdf. Under numa, a processor can access its own local memory faster than nonlocal memory memory local to another processor or memory shared between processors. Non uniform memory access numa shared memory multiprocessors.
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