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jargon [2016/11/10 20:31]
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jargon [2017/05/10 18:08] (current)
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 == node == == node ==
-a single computer in a box, functionally similar to a desktop computer but typically more powerful and packaged for rackmount in a datacenter. Implies shared memory for the programs running on the node.+a single computer in a box, functionally similar to a desktop computer but typically more powerful and packaged for rackmount in a datacenter. Usually two CPU sockets or four sockets with very large memory vs. one socket for a desktop. Implies shared memory for the programs running on the node.
  
 == cluster == == cluster ==
-a group of nodes connected by a network. Depending on budget and need for communication,​ the network may be inexpensive commodity (Gigabit ethernet) or faster and more expensive (Infiniband) or in between (10Gb Ethernet).+a group of nodes connected by a network. Depending on budget and need for communication,​ the network may be inexpensive commodity (Gigabit ethernet) or faster and more expensive (Infiniband ​or 40Gb Ethernet) or in between (10Gb Ethernet).
  
 == supercomputer == == supercomputer ==
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 == compute node == == compute node ==
-a cluster node dedicated to scientific computing tasks. Usually controlled by a scheduler program. Usually isolated from the public internet by head nodes.+a cluster node dedicated to scientific computing tasks. Usually controlled by a scheduler program. Usually isolated from the public internet by head nodes.  Usually has a high-speed network for running parallel computing and delivering files over the network.
  
 == head or login node == == head or login node ==
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 == GPU == == GPU ==
-a graphical processing unit, a specialized type of CPU derived from a graphics card. Effectively has hundreds of small cores. For certain tasks (those that can be effectively parallelized),​ is much faster than a general-purpose CPU.  Presently available versions must be attached to a PCI bus which is connected to and controlled by a CPU.  Also Xeon Phi, a CPU with many small cores which has the software interface of a general purpose CPU, but is used on highly parallel codes like a GPU.+a graphical processing unit, a specialized type of CPU derived from a graphics card. Effectively has hundreds of small cores. For certain tasks (those that can be effectively parallelized),​ is much faster than a general-purpose CPU.  Presently available versions ​are "​co-processors"​ that must be attached to a PCI bus which is connected to and controlled by a CPU.  Also Xeon Phi, a CPU with many small cores which has the software interface of a general purpose CPU, but is used on highly parallel codes like a GPU. Xeon Phi is available either as co-processor or as a CPU.
  
 == shared memory == == shared memory ==
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 == storage hierarchy == == storage hierarchy ==
-By analogy with memory hierarchy, the practice of using multiple disk storage systems with an HPC system. Each tier of storage is larger and slower than the preceding tier.  The first tier is relatively small and fast for a disk, usually composed of SSD, and does most direct data movement to the compute nodes. The last tier may be tape or large and inexpensive disk drives and holds longer term and larger files.+By analogy with memory hierarchy, the practice of using multiple disk storage systems with an HPC system. Each tier of storage is larger and slower than the preceding tier.  The first "​scratch" ​tier is relatively small and fast for a disk, usually composed of SSD, and does most direct data movement to the compute nodes. The last tier may be tape or large and inexpensive disk drives and holds longer term and larger files.
  
 == scratch file system == == scratch file system ==
-A temporary file system, designed for speed rather than reliability,​ and the first tier in the storage hierarchy. Usually composed of SSD.+A temporary file system, designed for speed rather than reliability,​ and the first tier in the storage hierarchy. Usually composed of faster disks, currently ​SSD.
  
 == SSD == == SSD ==
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 == VM or virtual machine == == VM or virtual machine ==
-a program running on a node that emulates a computer and connects the host computer'​s resources to the emulated computer. ​ The VM runs an operating system, which runs user programs, like a physical computer. Useful for programs that do not consume a lot of CPU time, and also useful to keep user programs from exceeding memory limits, and providing a way to save the state of a user program. A single powerful computer can run a number of VMs. +a program running on a node that emulates a computer and connects the host computer'​s resources to the emulated computer. ​ The VM runs an operating system, which runs user programs, like a physical computer. Useful for programs that do not consume a lot of CPU time, and also useful to keep user programs from exceeding memory limits, and providing a way to save the state of a user program. A single powerful computer can run a number of VMs. Also container as in Docker, a form of VM that is less isolated from the host computer than is a full VM.
  
 == HPC scheduler == == HPC scheduler ==
-A program that maintains a list of batch jobs to be executed on a cluster, ranks them in some priority order, and executes batch jobs on compute nodes as they become available. ​ Also OS scheduler, a program ​that runs on a shared-memory node and allows competing user programs access to CPU time, and IO scheduler, another ​program ​that arranges ​multiple disk accesses for a node.+A program that maintains a list of batch jobs to be executed on a cluster, ranks them in some priority order, and executes batch jobs on compute nodes as they become available. ​It tries to keep the cluster from being overloaded or idle. Also OS scheduler, a part of the kernel ​that runs on a shared-memory node and allows competing user programs access to CPU time, and IO scheduler, another ​part of the kernel ​that orders ​multiple disk accesses for a node.
  
 == parallel program == == parallel program ==
jargon.txt · Last modified: 2017/05/10 18:08 by root