Memory hierarchy: Difference between revisions

Revision as of 16:23, 30 April 2021

Revision as of 16:25, 30 April 2021

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* [[Processor register]]s – the fastest possible access (usually 1 CPU cycle). A few thousand bytes in size

* [[CPU cache|Cache]]

** Level 0 (L0) [[Micro-operation|Micro operations]] cache &ndash; 6,144 bytes (6 KiB)[[kilobyte|KB]]{{efn|name=prefix_memory|{{BDprefix|p=B}}}}<ref>{{cite web|url=http://www.anandtech.com/show/6355/intels-haswell-architecture/6 |title=Intel's Haswell Architecture Analyzed: Building a New PC and a New Intel |publisher=AnandTech |access-date=2014-07-31}}</ref> in size

** Level 1 (L1) [[Opcode|Instruction]] cache &ndash; 128 KiBKB{{efn|name=prefix_memory}} in size

** Level 1 (L1) Data cache &ndash; 128 KiBKB{{efn|name=prefix_memory}} in size. Best access speed is around 700 [[gigabyte|GB]]/s<ref name=sisd_qa_f_mem_hsw>{{cite web|url=http://www.sisoftware.co.uk/?d=qa&f=mem_hsw |title=SiSoftware Zone |publisher=Sisoftware.co.uk |access-date=2014-07-31|archive-url=https://web.archive.org/web/20140913231938/http://www.sisoftware.co.uk/?d=qa&f=mem_hsw|archive-date=2014-09-13}}</ref>

** Level 2 (L2) Instruction and data (shared) &ndash; 1 [[MiBmegabyte|MB]]{{efn|name=prefix_memory}} in size. Best access speed is around 200 GB/s<ref name=sisd_qa_f_mem_hsw />

** Level 3 (L3) Shared cache &ndash; 6 MiBMB{{efn|name=prefix_memory}} in size. Best access speed is around 100 GB/s<ref name=sisd_qa_f_mem_hsw />

** Level 4 (L4) Shared cache &ndash; 128 MiBMB{{efn|name=prefix_memory}} in size. Best access speed is around 40 GB/s<ref name=sisd_qa_f_mem_hsw />

* [[Computer memory|Main memory]] ([[Primary storage]]) &ndash; [[GiBGigabyte]]s{{efn|name=prefix_memory}} in size. Best access speed is around 10 GB/s.<ref name=sisd_qa_f_mem_hsw /> In the case of a [[Non-Uniform Memory Access|NUMA]] machine, access times may not be uniform

* [[Disk storage]] ([[Secondary storage]]) &ndash; [[TerabytesTerabyte]]s{{efn|name=prefix_storage|{{BDprefix|p=D}}}} in size. As of 2017, best access speed is from a consumer [[Solid-state drive|solid state drive]] is about 2000 MB/s<ref>{{cite web|url=http://www.storagereview.com/samsung_960_pro_m2_nvme_ssd_review|title=Samsung 960 Pro M.2 NVMe SSD Review|publisher=storagereview.com|access-date=2017-04-13}}</ref>

* [[Nearline storage]] ([[Tertiary storage]]) &ndash; Up to [[exabytes]]{{efn|name=prefix_storage}} in size. As of 2013, best access speed is about 160 MB/s<ref>{{cite web |url=http://www.lto.org/technology/generations.html |title=Ultrium - LTO Technology - Ultrium GenerationsLTO |publisher=Lto.org |access-date=2014-07-31 |url-status=dead |archive-url=https://web.archive.org/web/20110727052050/http://www.lto.org/technology/generations.html |archive-date=2011-07-27 }}</ref>

* [[Offline storage]]

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* [[Memory access pattern]]

* [[Communication-avoiding algorithm]]

==Notes==

{{notelist}}

==References==