Intel UltraPath Interconnect
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The Intel Ultra Path Interconnect (UPI) is a point-to-point
processor Processor may refer to: Computing Hardware * Processor (computing) **Central processing unit (CPU), the hardware within a computer that executes a program *** Microprocessor, a central processing unit contained on a single integrated circuit (I ...
interconnect In telecommunications, interconnection is the physical linking of a carrier's network with equipment or facilities not belonging to that network. The term may refer to a connection between a carrier's facilities and the equipment belonging to ...
developed by
Intel Intel Corporation is an American multinational corporation and technology company headquartered in Santa Clara, California. It is the world's largest semiconductor chip manufacturer by revenue, and is one of the developers of the x86 seri ...
which replaced the
Intel QuickPath Interconnect The Intel QuickPath Interconnect (QPI) is a point-to-point processor interconnect developed by Intel which replaced the front-side bus (FSB) in Xeon, Itanium, and certain desktop platforms starting in 2008. It increased the scalability and avai ...
(QPI) in
Xeon Xeon ( ) is a brand of x86 microprocessors designed, manufactured, and marketed by Intel, targeted at the non-consumer workstation, server, and embedded system markets. It was introduced in June 1998. Xeon processors are based on the same a ...
Skylake-SP platforms starting in 2017.


Interconnect

UPI is a
low-latency Latency, from a general point of view, is a time delay between the cause and the effect of some physical change in the system being observed. Lag, as it is known in gaming circles, refers to the latency between the input to a simulation and ...
coherent interconnect for scalable
multiprocessor Multiprocessing is the use of two or more central processing units (CPUs) within a single computer system. The term also refers to the ability of a system to support more than one processor or the ability to allocate tasks between them. There ar ...
systems with a shared address space. It uses a directory-based home snoop coherency protocol with a transfer speed of up to 10.4 
GT/s In computer technology, transfers per second and its more common secondary terms gigatransfers per second (abbreviated as GT/s) and megatransfers per second (MT/s) are informal language that refer to the number of operations transferring data that ...
. Supporting processors typically have two or three UPI links. Comparing to QPI, it improves power efficiency with a new low-power state, improves transfer efficiency with a new packetization format, and improves scalability with protocol layer that does not require preallocation of resources. UPI only supports directory-based coherency, unlike previous QPI processors which supported multiple snoop modes (no snoop, early snoop, home snoop, and directory). A combined caching and home agent (CHA) handles resolution of coherency across multiple processors, as well as snoop requests from processor cores and local and remote agents. Separate physical CHAs are placed within each processor core and last level cache (LLC) bank to improve scalability according to the number of cores, memory controllers, or the sub-
NUMA Nuclear mitotic apparatus protein 1 is a protein that in humans is encoded by the ''NUMA1'' gene. Interactions Nuclear mitotic apparatus protein 1 has been shown to interact with PIM1, Band 4.1, GPSM2 G-protein-signaling modulator 2, also call ...
clustering mode. The address space is interleaved across different CHAs, which act like a single logical agent.


See also

*
HyperTransport HyperTransport (HT), formerly known as Lightning Data Transport, is a technology for interconnection of computer processors. It is a bidirectional serial/ parallel high-bandwidth, low- latency point-to-point link that was introduced on Apri ...
*
Front-side bus A front-side bus (FSB) is a computer communication interface (bus) that was often used in Intel-chip-based computers during the 1990s and 2000s. The EV6 bus served the same function for competing AMD CPUs. Both typically carry data between the ...


References


External links


Intel® Xeon® Processor Scalable Family Technical Overview
{{DEFAULTSORT:Intel UltraPath Interconnect Computer buses UltraPath Interconnect Serial buses