{"id":397,"date":"2020-08-18T19:23:47","date_gmt":"2020-08-18T20:23:47","guid":{"rendered":"http:\/\/www.linux-tutorial.info\/?page_id=77"},"modified":"2020-08-22T19:26:16","modified_gmt":"2020-08-22T20:26:16","slug":"this-is-the-page-title-toplevel-230","status":"publish","type":"page","link":"http:\/\/www.linux-tutorial.info\/?page_id=397","title":{"rendered":"Memory Basics"},"content":{"rendered":"\n<title>Memory Basics<\/title>\nAll systems have a memory hierarchy with memory at different speeds and sizes\nat different points in the hierarchy.  The fastest memory is known as\ncache memory and is what it sounds like &#8211; memory that is used to temporarily hold, or\ncache, contents of the main memory.\nThis sort of memory is very fast but expensive, therefore most processors have\na small amount of on-chip cache memory and more system based (on-board) cache memory.\nSome processors have one cache to contain both instructions and data, but others have two,\none for instructions and the other for data. The Alpha AXP processor has two internal\nmemory caches; one for data (the D-Cache) and one for instructions (the I-Cache).\nThe external cache (or B-Cache) mixes the two together.\nFinally there is the main memory which, relative to the external cache memory,\nis very slow.\nRelative to the on-<glossary>CPU<\/glossary> cache, main memory is positively crawling.\n<p>\nThe cache and main memories must be kept in step (coherent).\nIn other words, if a word of main memory is held in one or more locations\nin cache, then the system must make sure that the contents of cache and\nmemory are the same.  The job of cache coherency is done partially by the\nhardware and partially by the operating system.\nThis is also true for a number of major system tasks where the hardware and software\nmust cooperate closely to achieve their aims.\n<p>\nDetails on memory in general can be found <site id=\"116\">here<\/site>.<br \/>\nDetails on cache memory can be found <site id=\"118\">here<\/site>.<br \/>\n","protected":false},"excerpt":{"rendered":"<p>Memory Basics All systems have a memory hierarchy with memory at different speeds and sizes at different points in the hierarchy. The fastest memory is known as cache memory and is what it sounds like &#8211; memory that is used &hellip; <a href=\"http:\/\/www.linux-tutorial.info\/?page_id=397\">Continue reading <span class=\"meta-nav\">&rarr;<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-397","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"http:\/\/www.linux-tutorial.info\/index.php?rest_route=\/wp\/v2\/pages\/397","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/www.linux-tutorial.info\/index.php?rest_route=\/wp\/v2\/pages"}],"about":[{"href":"http:\/\/www.linux-tutorial.info\/index.php?rest_route=\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"http:\/\/www.linux-tutorial.info\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/www.linux-tutorial.info\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=397"}],"version-history":[{"count":1,"href":"http:\/\/www.linux-tutorial.info\/index.php?rest_route=\/wp\/v2\/pages\/397\/revisions"}],"predecessor-version":[{"id":621,"href":"http:\/\/www.linux-tutorial.info\/index.php?rest_route=\/wp\/v2\/pages\/397\/revisions\/621"}],"wp:attachment":[{"href":"http:\/\/www.linux-tutorial.info\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=397"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}