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3.2.2 Scheduling Dictionary

 

 

Account
Definition: A credential also known as project ID. Multiple users may be associated a single account ID and each user may have access to multiple accounts. (See credential definition and ACCOUNTCFG parameter.)
Example: ACCOUNT=hgc13
 
ACL (Access Control List)
Definition: In the context of scheduling, an access control list is used and applied much as it is elsewhere. An ACL defines what credentials are required to access or use particular objects. The principal objects to which ACLs are applied are reservations and QoS's. ACLs may contain both allow and deny statements, include wildcards, and contain rules based on multiple object types.
Example: Reservation META1 contains 4 access statements.

Allow jobs owned by user john or bob
Allow jobs with QoS premium
Deny jobs in class debug
Allow jobs with a duration of less than 1 hour
   
Allocation
Definition: A logical, scalar unit assigned to users on a credential basis, providing access to a particular quantity of compute resources. Allocations are consumed by jobs associated with those credentials.
Example: ALLOCATION=30000
   
Class
Definition: (see Queue) A class is a logical container object that holds jobs allowing a site to associate various constraints and defaults to these jobs. Class access can also be tied to individual nodes defining whether a particular node will accept a job associated with a given class. Class based access to a node is denied unless explicitly allowed via resource manager configuration. Within Moab, classes are tied to jobs as a credential.
Example: job cw.073 is submitted to class batch

node cl02 accepts jobs in class batch

reservation weekend allows access to jobs in class batch
   
CPU
Definition: A single processing unit. A CPU is a consumable resource. Nodes typically consist of one or more CPUs. (same as processor )
   
Credential
Definition: An attribute associated with jobs and other objects that determines object identity. In the case of schedulers and resource managers, credential based policies and limits are often established. At submit time, jobs are associated with a number of credentials such as user, group , account , QoS, and class. These job credentials subject the job to various polices and grant it various types of access.

In most cases, credentials set both the privileges of the job and the ID of the actual job executable.
Example: Job cw.24001 possesses the following credentials:

USER=john;GROUP=staff;ACCOUNT=[NONE];
QOS=[DEFAULT];CLASS=batch
   
Disk
Definition: A quantity of local disk available for use by batch jobs. Disk is a consumable resource.
   
Execution Environment
Definition: A description of the environment in which the executable is launched. This environment may include attributes such as the following:
an executable
command line arguments
input file
output file
local user ID
local group ID
process resource limits
Example: Job cw.24001 possesses the following execution environment:

EXEC=/bin/sleep;ARGS="60";
INPUT=[NONE];OUTPUT=[NONE];
USER=loadl;GROUP=staff;
   
Fairshare
Definition: A mechanism that allows historical resource utilization information to be incorporated into job priority decisions.
   
Fairness
Definition: The access to shared compute resources that each user is granted. Access can be equal or based on factors such as historical resource usage, political issues, and job value.
   
Group
Definition: A credential typically directly mapping to a user's UNIX group ID.
   
Job
Definition: The fundamental object of resource consumption. A job contains the following components:
A list of required consumable resources
A list of resource constraints controlling which resources may be allocated to the job
A list of job constraints controlling where, when, and how the job should run
A list of credentials
An execution environment
   
Job Constraints
Definition: A set of conditions that must be fulfilled for the job to start. These conditions are far reaching and may include one or more of the following:
When the job may run. (After time X, within Y minutes.)
Which resources may be allocated. (For example, node must possess at least 512 MB of RAM, run only in partition or Partition C, or run on HostA and HostB.)
Starting job relative to a particular event. (Start after job X successfully completes.)
Example: RELEASETIME>='Tue Feb 12, 11:00AM'
DEPEND=AFTERANY:cw.2004
NODEMEMORY==256MB
   
Memory
Definition: A quantity of physical memory (RAM). Memory is provided by compute nodes. It is required as a constraint or consumed as a consumable resource by jobs. Within Moab, memory is tracked and reported in megabytes (MB).
Example: Node node001 provides the following resources:
PROCS=1,MEMORY=512,SWAP=1024

Job cw.24004 consumes the following resources per task:
PROCS=1,MEMORY=256
   
Node
Definition: A node is the fundamental object associated with compute resources. Each node contains the following components:
A list of consumable resources
A list of node attributes
   
Node Attribute
Definition: A node attribute is a non-quantitative aspect of a node. Attributes typically describe the node itself or possibly aspects of various node resources such as processors or memory. While it is probably not optimal to aggregate node and resource attributes together in this manner, it is common practice. Common node attributes include processor architecture, operating system, and processor speed. Jobs often specify that resources be allocated from nodes possessing certain node attributes.
Example: ARCH=AMD,OS=LINUX24,PROCSPEED=950
   
Node Feature
Definition: A node feature is a node attribute that is typically specified locally via a configuration file. Node features are opaque strings associated with the node by the resource manager that generally only have meaning to the end-user, or possibly to the scheduler. A node feature is commonly associated with a subset of nodes allowing end-users to request use of this subset by requiring that resources be allocated from nodes with this feature present. In many cases, node features are used to extend the information provided by the resource manager.
Example: FEATURE=s950,pIII,geology

(This may be used to indicate that the node possesses a 950 MHz Pentium III processor and that the node is owned by the Geology department.)
   
Processor
Definition: A processing unit. A processor is a consumable resource. Nodes typically consist of one or more processors. (same as CPU)
   
Quality of Service (QoS)
Definition: An object that provides special services, resources, and so forth.
   
Queue
Definition: (see Class )
   
Reservation
Definition: An object that reserves a specific collection or resources for a specific timeframe for use by jobs that meet specific conditions.
Example: Reserve 24 processors and 8 GB of memory from time T1 to time T2 for use by user X or jobs in the class batch.
   
Resource
Definition: Hardware, generic resources such as software, and features available on a node, including memory, disk, swap, and processors.
   
Resource, Available
Definition: A compute node's configured resources minus the maximum of the sum of the resources utilized by all job tasks running on the node and the resources dedicated; that is, R.Available = R.Configure - MAX(R.Dedicated,R.Utilized).

In most cases, resources utilized will be associated with compute jobs that the batch system has started on the compute nodes, although resource consumption may also come from the operating system or rogue processes outside of the batch system's knowledge or control. Further, in a well-managed system, utilized resources are less than or equal to dedicated resources and when exceptions are detected, one or more resource limit policies is activated to preempt the jobs violating their requested resource usage.
Example: Node 
cl003
has 4 processors and 512 MB of memory. It is executing 2 tasks of job 
clserver.0041
that are using 1 processor and 60 MB of memory each. One processor and 250 MB of memory are reserved for user 
jsmith
, but are not currently in use.

Node cl003's resources available to user

jsmith
:
  • 2 processors
  • 392 MB memory

Node cl003's resources available to a user other than

jsmith
:
  • 1 processor
  • 142 MB memory
   
Resource, Configured
Definition: The total amount of consumable resources that are available on a compute node for use by job tasks.
Example: Node 
cl003
has 4 processors and 512 MB of memory. It is executing 2 tasks of job 
clserver.0041
that are using 1 processor and 60 MB of memory each. One processor and 250 MB of memory are reserved for user 
jsmith
but are not currently in use.

Node cl003's configured resources:

  • 4 processors
  • 512 MB memory
   
Resource, Consumable
Definition: Any object that can be used (that is, consumed and thus made unavailable to another job) by, or dedicated to a job is considered to be a resource. Common examples of resources are a node's physical memory or local disk. As these resources may be given to one job and thus become unavailable to another, they are considered to be consumable. Other aspects of a node, such as its operating system, are not considered to be consumable since its use by one job does not preclude its use by another.

Note that some node objects, such as a network adapter, may be dedicated under some operating systems and resource managers and not under others. On systems where the network adapter cannot be dedicated and the network usage per job cannot be specified or tracked, network adapters are not considered to be resources, but rather attributes.

Nodes possess a specific quantity of consumable resources such as real memory, local disk, or processors. In a resource management system, the node manager may choose to report only those configured resources available to batch jobs. For example, a node may possess an 80-GB hard drive but may have only 20 GB dedicated to batch jobs. Consequently, the resource manager may report that the node has 20 GB of local disk available when idle. Jobs may explicitly request a certain quantity of consumable resources.
   
Resource, Constraint
Definition: A resource constraint imposes a rule on which resources can be used to match a resource request. Resource constraints either specify a required quantity and type of resource or a required node attribute. All resource constraints must be met by any given node to establish a match.
   
Resource, Dedicated
Definition: A job may request that a block of resources be dedicated while the job is executing. At other times, a certain number of resources may be reserved for use by a particular user or group. In these cases, the scheduler is responsible for guaranteeing that these resources, utilized or not, are set aside and made unavailable to other jobs.
Example: Node 
cl003
has 4 processors and 512 MB of memory. It is executing 2 tasks of job 
clserver.0041
that are using 1 processor and 60 MB of memory each. One processor and 250 MB of memory are reserved for user 
jsmith
but are not currently in use.

Node cl003's dedicated resources are:

  • 1 processor
  • 250 MB memory
   
Resource, Utilized
Definition: All consumable resources actually used by all job tasks running on the compute node.
Example: Node 
cl003
has 4 processors and 512 MB of memory. It is executing 2 tasks of job 
clserver.0041
that are using 1 processor and 60 MB of memory each. One processor and 250 MB of memory are reserved for user 
jsmith
but are not currently in use.

Node cl003's utilized resources are:

  • 2 processors
  • 120 MB memory
   
Swap
Definition: A quantity of virtual memory available for use by batch jobs. Swap is a consumable resource provided by nodes and consumed by jobs.
   
Task
Definition: An atomic collection of consumable resources.
   
User, Global
Definition: The user credential used to provide access to functions and resources. In local scheduling, global user IDs map directly to local user IDs.
   
User, Local
Definition: The user credential under which the job executable will be launched.
   
Workload
Definition: Generalized term.

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