Exploiting processor side channels to enable cross vm malicious code execution by sophia m. If we think about the programming of mimd parallel computers either shared or distributed memory in terms of management of numa memory hierarchy, then parallel. Lipasti university of wisconsinmadison lecture notes based on notes by john p. The pentium pro has an 8 kb instruction cache, from which up to 16 bytes are fetched on each cycle and sent to the instruction decoders. In our simple model, the memory system is a linear array of bytes, and the cpu can access each memory location in a. The relationship between this measure and more traditional cache miss rate is shown in 1. Moreover, since programs issue inegrained memory accesses, prior hardwarebased compression techniques focus on compress. The levels of a memory hierarchy 1 1 the levels of a memory hierarchy 2 2 some useful definitions when the cpu finds a. Us5423015a memory structure and method for shuffling a. Factorytalk view site edition users guide important user information read this document and the documents listed in the additional resources section about. Memory hierarchy level 1 instruction and data caches 2 cycle access time level 2 unified cache 6 cycle access time separate level 2 cache and memory address data bus icache 8kb dcache 8kb biu l2 cache 256kb main memory pci cpu 64 bit 16 bytes.
Memory hierarchy krste asanovic electrical engineering and computer sciences university of california, berkeley. At the top is the fastest, smallest, and most expensive memory, the registers. Designing for high performance requires considering the restrictions of the memory hierarchy, i. The design goal is to achieve an effective memory access time t10. However, problem with time is that processors are waiting for data from memory, the architects create a small piece of hardware l1 cache between registers and memory. In computer architecture, the memory hierarchy separates computer storage into a hierarchy. We have thought of memory as a single unit an array of bytes or words. So, fundamentally, the closer to the cpu a level in the memory hierarchy is. A series of optimizations targeted at the hierarchy of one ma. A realtime integrated hierarchical temporal memory network. From the perspective of a program running on the cpu, thats exactly what it looks like. In this paper, hmns only differ from regular memory networks in two of its components.
Lecture 8 memory hierarchy philadelphia university. A programmers perspective, third edition 22 the cpumemory gap the gap between dram, disk, and cpu speeds. For the first memory access, at 101102, the 3 lsb, to index the cache, are 110. Access times of level 1 cache, level 2 cache and main memory are 1 ns, 10ns, and 500 ns, respectively. An example memory hierarchy registers onchip l1 cache sram main memory dram local secondary storage local disks larger, slower, and cheaper per byte storage devices remote secondary storage distributed file systems, web servers local disks hold files retrieved from disks on remote network servers. Programming the memory hierarchy stanford graphics. Next lecture looks at supplementing electronic memory with disk storage. Memory hierarchy affects performance in computer architectural design, algorithm predictions, and lower level programming constructs involving locality of reference. An algorithm that uses lru policy at the successive levels of the memory hierarchy is shown to be optimal. Dantoine a thesis submitted to the graduate faculty of rensselaer polytechnic institute.
The memory hierarchy to this point in our study of systems, we have relied on a simple model of a computer system as a cpu that executes instructions and a memory system that holds instructions and data for the cpu. A performance evaluation of memory hierarchy in embedded. A realtime integrated hierarchical temporal memory network for the realtime continuous multiinterval prediction of data streams 42 j inf process syst, vol. Memory hierarchyreducing hit time, main memory, and examples professor david a. Streat, dhireesha kudithipudiy, kevin gomezx nanocomputing research laboratory, rochester institute of technology, rochester, ny 14623y. Memory consistency the memory consistency model establishes a contract between the memory system and the programmer when there can be concurrent reads and writes to a shared storage e. Memory hierarchyreducing hit time and main memory iram too. Since response time, complexity, and capacity are related, the levels may also be distinguished by their performance and controlling technologies. The memory hierarchy clocks are used to synchronize changes of state in sequential logic circuits. Memory hierarchy article about memory hierarchy by the free.
This section documents instances in which the behavior and default settings of the intel quartus prime pro edition software have been changed from earlier releases of. Instruction count memory accesses misses perinstructions. Drew conways venn diagram where the above quanti es the risk associated with this event. It also had a wider 36bit address bus usable by pae, allowing it to access up to 64 gb of memory. Online memory management algorithms for the hmm model are also considered. It is intended to model computers with multiple levels in the memory hierarchy. Deciding on the best coe cients and can be done quite easily by a host of software. While this is an effective model as far as it goes, it does not re. Fast memory technology is more expensive per bit than slower memory solution. The memory hierarchy on early computers was constituted by tree levels. The memory hierarchy 1 the possibility of organizing the memory subsystem of a computer as a hierarchy, with levels, each level having a larger capacity and being slower than the precedent level, was envisioned by the pioneers of digital computers. The initial development goals for the pentium iii processor were to balance performance, cost, and frequency.
The state of a sequential logic circuit can be changed either when the clock line is in a. A model for hierarchical memory alok aggarwal bowen alpern ashok k. Carnegie mellon bryant and ohallaron, computer systems. Descriptions of some of the key aspects of the simd floating point fp architecture and of the memory streaming architecture are given. A memory structure which can operate as a stack or list, the structure comprising a plurality of contiguous memory locations subdivided into contiguous substructures, each of the substructures having at least one buffer memory location associated with it, whereby stack or list shuffle operations can be performed in parallel on the substructures. Abstract in this paper we introduce the hierarchical memory model hmm of computation. A sequential logic circuit is a combinational circuit with one or more elements that retain state e. Cache behavior l1 is 32kb, 8 way set associative, 64 byte line size there are 512 bytes in a set, 64 sets total a1282 matrix exceeds l1scapacity arow uses 16 cachelines 128864,one afteranother. At the bottom, the largest, cheapest, and slowest memory, offline archival storage e.
In computer architecture, the memory hierarchy separates computer storage into a hierarchy based on response time. The upper levels of the memory hierarchy use electronic storage, the lower levels use blockaddressed magnetic storage. The pentium pro thus featured out of order execution, including speculative execution via register renaming. In practice, a memory system is a hierarchy of storage devices with different capacities, costs, and access times. Next memory hierarchy traditional hierarchy new hierarchy cpu far memory scale out ddrnvdimm near memory hbmwide io storage cache nvm storage ssdhdd cpu working memory ddr storage. Memory hierarchy our next topic is one that comes up in both architecture and operating systems classes. Use of numentas software and intellectual property, including the ideas contained in this. View test prep lec5 from cs 5700 at university of missouri, st. The main argument for having a memory hierarchy is economics. Dram memory cells are single ended in contrast to sram cells. As a measure of cache performance we use the number of misses per instructions.
1288 803 1243 597 1344 795 1001 480 1583 1445 654 477 1531 798 572 584 1493 397 819 280 252 241 146 586 1014 117 800 927 1409 823