This document provides an overview of the GlideinWMS matchmaking process within the CMS experiment at CERN, detailing its architecture and policies for resource provisioning. It explains the two levels of matchmaking, user job attributes, and various policies that govern resource allocation and job execution, including standard and overflow policies. Additionally, it discusses the complexities introduced by different user requirements and offers examples of job submission files.

1. glideinWMS for users
Matchmaking in glideinWMS
in CMS
by Igor Sfiligoi (UCSD)
CERN, Dec 2012 glideinWMS matchmaking 1

2. Scope of this talk
This talk provides a
high level description of how
glideinWMS matchmaking
works in CMS.
Reader is expected to be familiar with the CMS experiment environment
http://cms.web.cern.ch/
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3. glideinWMS architecture
● A reminder G.F.
+3
VO FE Grid
G.F.
+1
Execute node
Central manager Execute node
Submit node
Execute node
Negotiator
Submit node
Execute node
Submit node
Execute node
Schedd Condor
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4. Two levels of matchmaking
● First in the VO Frontend
● To decide where G.F.
to provision resources VO FE
+3
+1
G.F.
Grid
Execute node
● i.e. where Submit node
Central manager Execute node
Execute node
to send glideins
Negotiator
Submit node
Execute node
Submit node
Execute node
Schedd
Then in the
Condor
●
HTCondor Negotiator
● To decide The two
which Job gets the glidein Slot must have
compatible
policies
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5. Defining the policy
● The VO FE configures the glideins
● So it can define the Slot Requirements
● Preferred strategy to leave all policy
decisions in the VO FE hands, i.e. both
● VO FE matchmaking policy Easier keep them
in sync this way
● HTCondor matchmaking policy
● This implies
● Users should not define Job Requirements
● Instead, publish attributes describing requirements
http://www.slideshare.net/igor_sfiligoi/condor-week-12-attribute-matchmaking-move-req-out-of-user-hands
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6. CMS Production @ CERN
Policies
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7. Description
● The VO FE @ CERN serves
the production needs
● i.e. Reconstruction and MC production
● Job submission regulated by service managed
by a dedicated team,
so jobs are
● Targeted
● Well behaved
At least by and large
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8. Matchmaking policy
● Two dimensions
● Grid Site
● Single CPU vs HTPC
● The actual policy is the AND of both
● Both VO FE policy and HTCondor policy
defined in the VO FE instance configuration
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9. Matching on Grid site name
● User Jobs expected to publish the attribute
DESIRED_Sites String list
● e.g. +DESIRED_Sites = “T2_DE_DESY,T2_US_UCSD”
● The G.F. and the glideins advertising
GLIDEIN_CMSSite
● The matchmaking policy is
GLIDEIN_CMSSite ∈ DESIRED_Sites
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10. Matching on Job Type
● Use Jobs can publish the attribute
DESIRES_HTPC Integer representation of Boolean values
● e.g. +DESIRES_HTPS = 1
● If not defined, defaults to 0
● The G.F. And the glideins may advertise
GLIDEIN_Is_HTPC Boolean value
● If not defined, defaults to False
● The matchmaking policy is
(GLIDEIN_Is_HTPC==True)==(DESIRES_HTPC==1)
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11. Example submit file
Universe
Universe = vanilla
= vanilla
Executable = mcgen
Executable = mcgen
Arguments = -k 1543.3
Arguments = -k 1543.3
Output
Output = mcgen.out
= mcgen.out
Error
Error = mcgen.err
= mcgen.err
Log
Log = mcgen.log
= mcgen.log
+DESIRED_Sites = “T2_DE_DESY,T2_US_UCSD”
+DESIRED_Sites = “T2_DE_DESY,T2_US_UCSD”
+DESIRES_HTPC = 0
+DESIRES_HTPC = 0
Requirements = True
Requirements = True
Queue 1
Queue 1
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12. CMS AnaOps @ UCSD
Policies
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13. Description
● VO FE @ UCSD serves CMS analysis users
● User Jobs much more chaotic
● Most users don't really understand their needs
● Must protect from accidental errors
● Yet keep the system flexible
● Net result
● More complex policy
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14. Two different policies
● The AnaOps FE actually has two policies
● The Regular policy
● The Overflow policy
● The Regular policy tries to match resources
● Based on User desires
● The Overflow policy “outsmarts” the Users
● Will violate User desires without breaking the Jobs
● The aim is to finish user jobs sooner
● User can opt-out, if he wishes
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15. The Regular M.M. policy
● Four+one dimensions
● Grid Site
● Single CPU vs HTPC
● Memory usage
● Job duration
Due to preemption
● Number of Job Starts
● The actual policy is the AND of both
● Both VO FE policy and HTCondor policy
defined in the VO FE instance configuration
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16. Grid site selection
● This is both similar and different compared to
the Production FE @CERN
● Serves the same purpose, but supports three
different ways to select a site
– Due to historical evolution
● The three options are
● GLIDEIN_CMSSite ∈ DESIRED_Sites
Planning to extend to
● GLIDEIN_SEs ∈ DESIRED_SEs (GLIDEIN_SEs ∩ DESIRED_SEs) ≠∅
● GLIDEIN_Gatekeeper ∈ DESIRED_Gatekeepers
● The actual policy is the OR of the three
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17. Job type selection
● Just like @ CERN
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18. Memory Usage
● Most Grid sites put strict limits on the amount of
memory that can be used
● Will kill glideins if they exceed the limit
● G.F. and glideins advertise the Entry-specific limit
GLIDEIN_MaxMemMBs
● Jobs can explicitly declare the needed memory
request_memory Native Condor attribute, no + needed
● Condor will also measure it at run time Use a combination
of these to calculate
– ImageSize – Virtual memory used the actual JobMemory
– ResidentSetSize – True memory usage
● Policy: JobMemory <= GLIDEIN_MaxMemMBs
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19. Job Duration 1/2
● Glideins have a limited lifetime
● Must fit within the limits of the Grid site's queue
● Glideins publish the deadline
GLIDEIN_ToDie
– Jobs must finish before reaching the deadline
● Final user job lifetime unpredictable
● Depends on the type of computing done
● User should indicate the expected job lifetime
– Else we have to assume reasonable defaults
Not many users set
this value(s) right now
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20. Job Duration 2/2
● The same type of computation may take
different amount of time
● e.g. Based on the type of input
● Jobs can declare two attributes
● NormMaxWallTimeMins – Expected limit
● MaxWallTimeMins – Absolute max limit
● The matchmaking logic is
● Use NormMaxWallTimeMins for
Based on simple assumption
the first job startup that the job was killed for
hitting the deadline.
● Use MaxWallTimeMins for all others
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21. Cut on number of re-starts
● Not really a user configurable property
● More an emergency break
● In a properly configured system,
should never be triggered
● But unexpected problems happen
● So better limit the damage
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22. The Overflow Use case
● User Jobs specify a list of sites,
because the data they need is there
● With recent versions of CMSSW, jobs can
access the data from remote
● With a small performance penalty
● We can thus schedule jobs “anywhere”
● As long as the needed data is
at a Site that has joined the xrootd federation
● But only if no CPU available “close to the data”
– And not too far, either
http://indico.cern.ch/contributionDisplay.py?contribId=381&sessionId=5&confId=149557
http://indico.cern.ch/contributionDisplay.py?contribId=232&sessionId=8&confId=149557
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23. The Overflow M.M. policy
● Violate only the “Site selection” rule
● Keep all the others
● Plus, add one+one more:
● An opt-out mechanism
● Delayed matching
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24. New Site M.M. policy
● The user specified attribute is used
to flag the job as “Overflowable”
● i.e. the job will match if and only if
(DESIRED_<site>s ∩ SUPPORTED_<site>s) ≠∅
Still support all 3 types of site identification
● Matching jobs can then run on any glidein
● Additional limits can be put in place by the FE,
but mostly invisible to the user
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25. The opt-out mechanism
● The Overflow policy
considers all jobs by default
● But Users may want to opt-out some of the Jobs
– Sometimes it is just a need
(to get deterministic results, e.g. for testing a site)
● To opt-out, the user defines
+CMS_ALLOW_OVERFLOW = False
● The FE will not consider such jobs for Overflowing
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26. Delayed matching
● As said initially,
Jobs should preferentially run close to the data
● Overflow should only consider jobs
“that cannot find resources close to the data”
● We implemented it based on time
● Jobs are matched only
if waiting in the queue for more than 6 hours
Users cannot influence it
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27. Example submit file
Universe
Universe = vanilla
= vanilla
Executable = myana
Executable = myana
Arguments = -k 1543.3
Arguments = -k 1543.3
Output
Output = myana.out
= myana.out
Error
Error = myana.err
= myana.err
Log
Log = myana.log
= myana.log
request_memory = 1500
request_memory = 1500
+DESIRED_SEs = "dc2-grid-64.brunel.ac.uk,stormfe1.pi.infn.it"
+DESIRED_SEs = "dc2-grid-64.brunel.ac.uk,stormfe1.pi.infn.it"
+NormMaxWallTimeMins = 7200
+NormMaxWallTimeMins = 7200
+MaxWallTimeMins = 14400
+MaxWallTimeMins = 14400
+DESIRES_HTPC = 0
+DESIRES_HTPC = 0
+CMS_ALLOW_OVERFLOW = True
+CMS_ALLOW_OVERFLOW = True
Requirements = True
Requirements = True
Queue 1
Queue 1
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28. The End
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29. Pointers
● glideinWMS Home Page
http://tinyurl.com/glideinWMS
● HTCondor Home Page
http://research.cs.wisc.edu/htcondor/
● HTCondor support
htcondor-users@cs.wisc.edu
htcondor-admin@cs.wisc.edu
● glideinWMS support
glideinwms-support@fnal.gov
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30. Acknowledgments
● The creation of this document was sponsored
by grants from the US NSF and US DOE,
and by the University of California system
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