Cache memory

Because of the relative slowness of main memory (compared with the CPU), most computers have a much smaller, but much faster cache memory subsystem that augments main memory. The size of the cache memory and the extent to which a program can utilize the cache can be critical deterrninants of performance. Again, there are some common optimization techniques designed to maximize cache utilization. 

Rossum also proposed the use of a cache memory [Rossum, 1994b] as part of the memory lookup path in a sampler interpolator. Since in many cases, the phase increment is less than one, the cache will be hit on the integer part of the table address, consequently, the memory will be free to use for other voices. 

Rossum, 1994b] Rossum, D. P. (1994b). Digital sampling instrument employing cache memory. U.S. Patent 5,342,990. 

Another 3D demonstration that used adhesive bonding included In-Au microbumps for interwafer interconnection and was reported by Lee et al. in 2000 [45]. A large shared cache memory was stacked above a processor to enable memory-intensive applications such as multiple processor computing, using 1.5-pm gate-length technology and doped polysilicon. 

CPU utilization Cache memory utilization Disk capacity utilization Interactive response time Number of transactions per time unit Average job waiting time Print queue times I/O load... 

As Internet information may be held in the cached memory on servers other than those of the originating organization (e.g., some public search engines), consideration should be given to clearly marking the information with the date/time on which it is was published. This is needed to distinguish it from the date/time it could be printed out by readers, and should be incorporated into the OQ and PQ testing undertaken before the Web site is released or updated. 

NUMA is one of the fundamental concepts needed to understand the design of a parallel software application. Every modern computer has several levels of memory, and parallel computers tend to have more levels than uniprocessors. Typical memory levels in a parallel computer include the processor registers, local cache memory, local main memory, and remote memory. If the parallel computer supports virtual memory, local and remote disk are added to this hierarchy. These levels vary in size, speed, and method of access. In this chapter, we will lump all these differences under the general term nonuniform memory access (NUMA). Note that this is a broader use of the term than is often found in computer science literature, where NUMA often refers only to differences in the speed with which given memory items can be accessed using the same method. In our use, memory access is often synonymous with data transfer. ... 

The Microarchitecture is a lower level, more concrete, description of the system. It involves such details as how the constituent parts of the system are interconnected and how they interoperate in order to implement the instruction set architecture. For example, the size of a computer s cache memory is an organizational issue which, in general, has nothing to do with the instruction set architecture. 

Communication ports SIMM and DIMM Processor sockets External cache memory (Level 2)... 

Don t forget, there s more to a chip than what meets the eye. There are several factors that affect the performance of a processor. Among them are availability of a math coprocessor, clock speed, internal cache memory, and supporting circuitry. 

Cache memory is a storage area for frequently used data and instructions. It requires a small amount of physical RAM that can keep up with the processor. It uses this RAM for storage. The processor contains an internal cache controller that integrates the cache with the CPU. The controller stores frequently accessed RAM locations to provide faster execution of data and instructions. This type of cache is known as a Level 1 Cache. It is also possible to have a cache external to the CPU, called a Level 2 Cache. This type of cache performs the same functions as a Level 1 Cache and can speed up the perceived performance. Basically, a larger cache leads to the perception of a faster CPU. 

SRAM The S in SRAM stands for static. Static random access memory doesn t require the refresh signal that DRAM does. The chips are more complex and are thus more expensive. However, they are faster. DRAM access times come in at 80 nanoseconds (ns) or more SRAM has access times of 15 to 20 ns. SRAM is often used for cache memory. 

C. An internal cache memory is a storage area for frequently used data and instructions. It requires a small amount of physical RAM that can keep up with the processor. 

When a CPU goes to get either its program instructions or data, it always has to get them from main memory. However, in some systems, there is a small amount of very fast SRAM memory, called cache memory, between the processor and main memory, and it is used to store the most frequently accessed information. Because it s faster than main memory and contains the most frequently used information, cache memory will increase the performance of any system. 

There are two types of cache memory on-chip (also called internal or LI Cache) and off-chip (also called external or L2 Cache). Internal cache memory is found on Intel Pentium, Pentium Pro, and Pentium II processors, as well as on other manufacturer s chips. The original Pentium contains two 8KB-on-chip caches, one for program instructions and the other for data. External cache memory is typically either a SIMM of SRAM or a separate expansion board that installs in a special processor-direct bus. 

To get the most out of cache memory, if you have the option of installing an external cache card onto your motherboard, do it. It can give you as much as a 25 percent boost in speed. 

LI Cache Any cache memory that is integrated into the CPU. 

A. Dynamic Random Access Memory (DRAM) is the type of memory that is expanded when you add memory. Static Random Access Memory (SRAM) is often used for cache memory. See Chapter 2 for more information. 

W.H. Henkels, L.M. Geppert, J. Kadlec, P.W. Epperlein, H. Beha, W.H. Chang, and H. Jaeckel, Josephson 4 K-bit Cache Memory Design for a Prototype Signal Processor. I. General Overview, J. Appl. Phys. 56,2371 (1985). 

Figure 4.4 The AMD Quad-Core Opteron microprocessor chip has four separate processors that act in paraiiei. The cores are the four iarge areas of irreguiar geometry, whiie the cache memory is shown in the gridiike regions and hoids cache memory. The totai siiicon area of 285 mm hoids 463 miiiion transistors. The criticai dimension is 65 nm. (Courtesy of AMD.)...

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