1. QoS in the Tier1 batch system(LSF)
Alessandro Italiano (INFN-CNAF)
Tier1 - Farming Group

2. QoS definition
From WikiPedia:
Quality of service is the ability to provide different priority to different applications and users in resource usage.
QoS mechanisms are not required if there is not resource contention

3. Tier1 scenario More than 20 different Experiments(Application)
Each Experiment has several computing activities with different priorities
Each year the Tier1 committee defines the highest amount of resources that each Experiment can use

4. From LSF Documentation
FairShare definition
From LSF Documentation
Fairshare scheduling divides the processing power of the LSF cluster among users to provide fair access to resources, so that no user or subgroup of users can monopolize the resources of the cluster

5. Hierarchical FairShare
a first level of QoS
Define dynamic priorities for every group/subgroup
Dynamically grants a resource quota to each group/subgroup
Used only where there is resource contention
Optimized resource usage

6. Hierarchical Fairshare: Parameters
Share assigned
Resource percentage assigned to every group e subgroup
Resource usage
Time Window
time slot used to compute the total amount of resources used by every group
Normalization factors
Dynamic priority formula:
Share
DP =
(ResourceUsage x Nf) + 1

7. Hierachical Fairshare: How it works
cms
rel share = 15
abs share = 4.5
cmsprd
rel share = 70
abs share = 21
cmssgm
alice
abs share = 4.05
alicesgm
rel share = 85
abs share = 22.95
Available Resources
CMS
share = 30
ALICE
share = 27
SHARE_INFO_FOR: SLC4_GLOBAL/
USER/GROUP SHARES PRIORITY STARTED RESERVED CPU_TIME RUN_TIMEgroup_test group_admin group_dteam group_egee group_ops group_magic group_ams group_ingv group_theophys group_biomed group_t1bio group_cdfcaf group_infngrid group_pamela group_lhcb u_cms group_babar u_atlas group_alice group_argo group_virgo

8. Hierarchical Fairshare: constraint
In case of no intra-VO resources contention, one user could use all the resources available to his experiment. In this way all the others users, also those belong to high priority group, could wait for a long time before to run a job

9. LSF SLA Second level of QoS
LSF Service Level Agreement are batch system
functionalities which can provide different
service level goals oriented.
There are four goals available:
Deadline: complete a specified #jobs in a time window
Velocity: maintain #jobs running in a time window. Used for short jobs
Throughput: complete #jobs per hour. Used for medium and long jobs
Combination of different goals

10. the specific SLA to each user or subgroup
LSF SLA: Constraint
You can’t configure a specific queue or user subgroup to use a SLA, because SLAs can be only invoked at submission time. To avoid this limitation the batch manager can easily provide an automatic hook in order to grant
the specific SLA to each user or subgroup

11. A detail which can improve QoS:
One queue for each Application in order to
customized execution environment and make easier the administration of application requirements
Run time resources limits
Dedicate computing resources
Use specific computing architectures
Queue administrator
Scheduling parameters
Pre and post execution script ……

12. How GRID can match the right service class ?
LSF QoS
Role: cms
QoS: Low Priority
Role: cmsprd
QoS: Medium Priority
Role: cmssgm
QoS: High Priority

13. Matching service class: Statically
GRID
LSF QoS
Role: cms
QoS: Low Priority
lcmaps configuration file
"/VO=cms/GROUP=/cms/ROLE=lcgadmin" cmssgm"/VO=cms/GROUP=/cms/ROLE=production" .cmsprd"/VO=cms/GROUP=/cms/HeavyIons/" .cms
Role: cmsprd
QoS: Medium Priority
Role: cmssgm
QoS: High Priority

14. Matching service class: Dynamically
GRID
LSF QoS
Role: cms
QoS: Low Priority
GPBox
Role: cmsprd
QoS: Medium Priority
Role: cmssgm
QoS: High Priority