Memory Hierarchy • Computer Memory Hierarchy is a pyramid structure that is commonly used to illustrate the significant differences among memory types. /ProcSet [/PDF /Text] Figure 2.1 shows a multilevel memory hierarchy, including typical sizes and speeds of access. <> /ProcSet [/PDF /Text] At each level in the hierarchy " Block placement " Finding a block " Replacement on a miss " Write policy The BIG Picture 80 . COMP 140 – Summer 2014 ! << 1 0 obj << stream endstream >> The memory hierarchy characteristics mainly include the following. 6 Lower Level Upper Level Memory Memory To Processor From Processor Block X Block Y Memory Hierarchy: Principle At any given time, data is copied between only two adjacent levels: –Upper level: the one closer to the processor Smaller, faster, uses more expensive technology –Lower level: the one away from the processor Bigger, slower, uses less expensive technology Common principles apply at all levels of the memory hierarchy " Based on notions of caching ! /Parent 3 0 R /Resources<< x��T�J1}_�?�1yh�m7)�������R|Xk/^Z������LR���B3399��d_I�h��F������ZVNX괤��J:�bL�! So, the enhancement was mandatory. /ModDate (D:20070102223052) Fundamental idea of a memory hierarchy: – For each k, the faster, smaller device at level k serves as a cache for the larger, slower device at level k+1. Performance is the key reason for having a memory hierarchy. Services and develop a library of Memory Services for common irregular data structures and algorithms. >> %äüöß /Length 14 0 R The memory hierarchy is a hierarchical collection of storage technologies that include processor registers, main memory, disk storage and even the internet as a storage medium. /Parent 3 0 R /Type /Page x��Z�n$���(ݪ,��&���9x���aܢF��46 ����"2����b�0hvfg��2�Ed��x���}�p��;\��8�R�4��˜����p������?b�ׇ7����ѷ���'��k]��b��[���6�.r�q~0��7��j��Ձ\�����ߦ)����껃gݤ���>E�ߧ��������˥�o��_/Ò�7ǿ\}}���$���P7��t�K��Ir��=}��r���%Խ�w$���K��}Ld���妔�BE��3�pb�o��4������ �h�=�G�����0���K���A�P��L�#�s�?M���q��. 5 0 obj 202 endobj %PDF-1.4 Performance Previously, the designing of a computer system was done without memory hierarchy, and the speed gap among the main memory as well as the CPU registers enhances because of the huge disparity in access time, which will cause the lower performance of the system. endobj The Memory Hierarchy ! /Contents 4 0 R CISC-221 Computer Architecture Topic #5: The Memory Hierarchy Learning Guide Background Previously, we have been exposed to the concept of the "memory hierarchy" of a typical computer system. 2. >> stream 2 0 obj << /MediaBox[0 0 842 595] /Creator 7 0 obj << At each level in the hierarchy " Block placement " Finding a block " Replacement on a miss " Write policy The BIG Picture 80 . A Hierarchical Memory System – or Memory Hierarchy for short – is an economical solution to provide computer programs with (virtually) unlimited fast memory, taking advantage of locality and cost-performance of memory technology. )�H�J���PI�~X���LSe�4�1 pNia ��І�zB���9��P���qRHGKe�w��.yG �\��͹�쉇�}\�1���U>��[ƛ�t�ѯ��W� x��Ɏ�6���9������`���F�֓r�4�0�A����n�(U�d�����^`�v�2(��������?�=}�6�!h���_B��B+tWG�CL���>��f����O���\V�������4����:|x� 0���ˤ�r���7)�_����i�l'�WAvyoT��WuS3�/g�ԃ?����aE� ��%��FBpK�� Rr�����x=}ZIaF���� s)l��8�%���D�a< endstream 5��_e鱚�D�|v)&�o��i��:�Kь!nuN7QgV���ப!�U{���j���ƶ��i�: The enhancement of this was designed i… /Type /Page "-�B&οǸ�=ݭ� ���K�&�pG����Ǜ�x>4�I��+!�����B�l��f�ߐ�gC�_�}=H�s���!��N��#�5_��$$]��lH�]^�G$�WF�?L>��8���. stream >> /Filter /FlateDecode COMP 140 – Summer 2014 ! !��,���g�!2x��H�j~��^H�"�]|���8 endobj Autumn 2006 CSE P548 - Memory Hierarchy 1 Introduction Why memory subsystem design is important • CPU speeds increase 25%-30% per year • DRAM speeds increase 2%-11% per year Autumn 2006 CSE P548 - Memory Hierarchy 2 Memory Hierarchy Levels of memory with different sizes & speeds • close to the CPU: small, fast access Figure 2.1. �.C��z�w�%����n�X|=p��� b�BK 13 0 obj It ranges from the slowest but high capacity auxiliary memory to the fastest but low capacity cache memory. Memory Hierarchy 19 CS @VT Computer Organization II ©2005-2013 CS:APP & McQuain Caches Cache: a smaller, faster storage device that acts as a staging area for a subset of the data in a larger, slower device. /F1 6 0 R>> >> /F2 10 0 R /F1 6 0 R /F3 11 0 R>> /Contents 8 0 R In our simple model, the memory system is a linear array of bytes, and the CPU can access each memory location in a constant amount of time. A clock cycle is the period of the wave form that the clock generates, i.e., the length of a clock cycle is the amount of time from the start of a high value to the start of the next high value, so it is measured in time units. �n���p2� x;6A���l�;�Y�%���%���7²&oBy�åPJW� x��O=�A��R����>QD�x��X���>=�ߛUA�G L&afr�ְu�Z�S����&E�Cjj���O�X6��p4u:�Z,[p�Y��Sf�>w��K=6����zmOI�+��& We design Livia, an efficient system architecture for the Memory Services model. >> The faster memories are more expensive per bit and thus tend to be smaller. Livia distributes special-ized Memory Service Elements (MSEs) throughout the memory hierarchy that schedule and execute Memory Service tasks. >> endobj >> }��;n$�5���2�Ǭ���'���'=�-�6DȐ:,�w,�Q�jR�[email protected]�Ô�Hu�G#�����|ȋѿ�3��f^��P%�1ۋx�0�#!G�u��G�啡n���,��� /Length 5 0 R /MediaBox[0 0 842 595] /Filter /FlateDecode Memory Hierarchy Design Memory hierarchy design becomes more crucial with recent multi-core processors: Aggregate peak bandwidth grows with # cores: Intel Core i7 can generate two references per core per clock Four cores and 3.2 GHz clock 25.6 billion 64-bit data references/second + Chapter 5 — Large and Fast: Exploiting Memory Hierarchy — 3 Principle of Locality Programs access a small proportion of their address space at any time Temporal locality (in time) Items accessed recently are likely to be accessed again soon e.g., instructions in a loop, induction variables Spatial locality (in space) Items near those accessed recently are likely to endobj Memory Hierarchy 9 More than 2 levels of memory Transfer between memory in level i and i+1 follows same principle, regardless of i Hierarchy: if item in level i, then it is also in level i+1 Hence, we restrict our discussion to 2 levels 1 Processor 2 3 4 Philipp Koehn Computer Systems Fundamentals: Memory Hierarchy 14 October 2019