7.3 Quality of Service (QoS) Facilities
7.3.1 QoS Overview
The QOS facility allows a site to give special treatment to various classes of jobs, users, groups, etc. Each QOS object can be thought of as a container of special privileges ranging from fairness policy exemptions, to special job prioritization, to special functionality access. Each QOS object also has an extensive access list of users, groups, and accounts which can access these privileges.
Sites can configure various QOS's each with its own set of priorities, policy exemptions, and special resource access settings. They can then configure user, group, account, and class access to these QOS's. A given job will have a default QOS and may have access to several additional QOS's. When the job is submitted, the submittor may request a specific QOS (see the User's Manual for information on specifying job QOS for the resource manager of interest) or just allow the default QOS to be used. Once a job is submitted, a user may adjust the QOS of his job's at any time using the 'setqos' command. The setqos command will only allow the user to modify the QOS of his jobs and only change the QOS to a QOS that this user has access to. Maui administrators may change the QOS of any job to any value.
Jobs are currently granted access to QOS privileges by configuring QDEF (QOS Default) or QLIST (QOS Access List) settings in the fs.cfg file. A job may access a particular QOS if that QOS is listed in the system default configuration QDEF or QLIST, or if the QOS is specified in the QDEF or QLIST of a user, group, account, or class associated with that job.
The 'diagnose -Q' command can be used to obtain information about the current QOS configuration.
With the Moab Cluster ManagerTM, a QoS can be created, modifed and reports generated about through a graphical interface.
7.3.2 QoS Enabled Privileges
The privileges enabled via QoS settings may be broken into one of the following categories- Special Prioritization
- Service Access and Constraints
- Override Policies and Policy Exemptions
7.3.2.1 Special Prioritization
| Attribute Name | Description |
| FSTARGET | |
| PRIORITY | Assign priority to all jobs requesting particular QoS |
| QTTARGET | |
| QTWEIGHT | |
| XFTARGET | |
| XFWEIGHT |
Example:
---
QOSCFG[geo] PRIORITY=10000
---
7.3.2.2 Service Access and Constraints
The QoS facility can ne used to enable special service and/or disable default services. All services are enabled/disabled by setting the QoS QFLAGS attribute.
| Flag Name | Description |
| DEDICATED | jobs should not share compute resources with any other job. These jobs will only run on nodes which are idle and will not allow other jobs to use resources on allocated nodes even if additional resources are available. |
| NOBF | job cannot be considered for backfilled |
| NORESERVATION | job should never reserve resources regardless of priority |
| PREEMPTEE | job may be preempted by higher priority PREEMPTOR jobs |
| PREEMPTOR | job may preempt lower priority PREEMPTEE jobs |
| RESERVEALWAYS | job should create resource reservation regardless of job priority |
| RESTARTPREEMPT | jobs can preempt restartable jobs by essentially requeueing them if this allows the QOS job to start earlier |
| USERESERVED[:<RESID>] | job may only utilize resources within accessible reservations. If <RESID> is specified, job may only utilize resources within the specified reservation. |
Example:
---
QOSCFG[hiprio] QFLAGS=NOBF:PREEMPTEE
---
Example 2:
---
QOSCFG[chem-b] QFLAGS=USERESERVED:chemistry
---
7.3.2.3 Policy Exemptions
Individual QoS's may be assigned override policies which will set new policy limits regardless of user, group, account, or queue limits. Particularly, the following policies may be overridden:
MAXJOB
MAXPROC
MAXNODE
Example:
---
QOSCFG[staff] MAXJOB=48
---
In addition to overriding policies, QoS's may also be used to allow particular jobs to ignore policies by setting the QoS FLAG attribute
QOS Flags
IGNJOBPERUSER
IGNPROCPERUSER
IGNPSPERUSER
IGNJOBQUEUEDPERUSER
IGNJOBPERGROUP
IGNPROCPERGROUP
IGNPSPERGROUP
IGNJOBQUEUEDPERGROUP
IGNJOBPERACCOUNT
IGNPROCPERACCOUNT
IGNPSPERACCOUNT
IGNJOBQUEUEDPERACCOUNT
IGNSYSMAXPROC
IGNSYSMAXTIME
IGNSYSMAXPS
IGNSRMAXTIME
jobs should ignore standing reservation MAXTIME constraints
IGNUSER
jobs should ignore all user throttling policies
IGNGROUP
jobs should ignore all group throttling policies
IGNACCOUNT
jobs should ignore all account throttling policies
IGNSYSTEM
jobs should ignore all system throttling policies
IGNALL
jobs should ignore all user, group, and account throttling policies
Example
---
QOSCFG[express] QFLAGS=IGNSYSTEM
---
7.3.3 Managing QoS Access
While defining the privileges allowed within a QoS is managed using the QOSCFG parameter, actual access to the QoS is enabled via credential specific *CFG parameters. Specifically, the USERCFG, GROUPCFG, ACCOUNTCFG, and CLASSCFG parameters allow QoS access lists and QoS defaults to be defined. To enable QoS access, the QLIST and/or QDEF attributes of the appropriate user, group, account, or queue should be specified as in the example below:
Example:
--- # user john's jobs can access QOS geo, chem, or staff with geo as default USERCFG[john] QDEF=geo QLIST=geo,chem,staff # group system jobs can access the development qos GROUPCFG[systems] QDEF=development # class batch jobs can access the normal qos CLASSCFG[batch] QDEF=normal ---
NOTE: By default, jobs may request a QoS if access to that QoS is allowed by any of the job's credentials. (i.e., in the example above, a job from user john submitted to the class batch could request QoS's geo, chem, staff, or normal)
See also:
N/A