using systemtap to analyze performance and funconal problems · this is only a short (non...

Whatdoesmymachinereallydo?

UsingSystemtaptoanalyzeperformanceandfunc9onalproblems

Studentpresenta9on@CernSchoolofCompu9ng2009MalteNuhn<malte.nuhn(at)rwth‐aachen.de>

Thisisonlyashort(nontechnical)appe9zer.Alotoftechnicaldetailswerehidden

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MonitoringGrid‐Jobs

•  LHCCompu9ngGrid•  Workernodesthatexecutejobs

•  8jobspermachine,novirtualiza9on

•  Ques9on:– Whattrafficisproducedbywhichjob?

Job1Job2Job3

Network ?8/26/09 3Systemtap‐CernSchoolofCompu9ng‐MalteNuhn

Networktrafficpernode:

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NetworkTraffi

c(M

byte/sec)

Time(sec)

Networktrafficpernode:

5Systemtap‐CernSchoolofCompu9ng‐MalteNuhn8/26/09

NetworkTraffi

c(M

byte/sec)

Time(sec)

Wanttoknowmoredetails

Whyisitsodifficulttolookatthedetailsofmymachine?

•  YouarerunningLinux•  LinuxisOpenSource•  Youevenownyourhardware

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Hmm...

©Constan<neShulyupin‐hCp://www.makelinux.net/kernel_map8/26/09 7Systemtap‐CernSchoolofCompu9ng‐MalteNuhn

ProbingtheKernel#1

Differentapproaches:Longtermstabilityvs.vividdevelopment8/26/09 8Systemtap‐CernSchoolofCompu9ng‐MalteNuhn

ProbingtheKernel#2

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Probingframework:Systemtap

•  Systemtapisyourfriend:– Copeswithallthedanger– Providesasimplescrip9nglanguage– Translatesscriptsintoasecurekernelmodules– Providesmaintained„Tapsets“foreverydayuse!

– Myopinion:Itisnotjustanother„geek“toy!Linuxhasalwayslackedsuchatool!

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Networktrafficpernode:

11Systemtap‐CernSchoolofCompu9ng‐MalteNuhn8/26/09

NetworkTraffi

c(M

byte/sec)

Time(sec)

Networktrafficpernode:

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NetworkTraffi

c(M

byte/sec)

Time(sec)

Networktrafficperjob:

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NetworkTraffi

c(M

byte/sec)

Time(sec)

Seeindividualjobs

Networktrafficperjob:

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NetworkTraffi

c(M

byte/sec)

Time(sec)

Seeindividualjobs

Detailednetworktrafficforonejob:

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NetworkTraffi

c(M

byte/sec)

Time(sec)

SeecontactedHosts

Summary:Systemtap

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Addi9onalinforma9on

Systemtap:•  hhp://sourceware.org/systemtap/•  hhp://www.redbooks.ibm.com/abstracts/redp4469.html

•  #systemtaponirc.freenode.net

LinuxKernel:•  hhp://kernelnewbies.org/

8/26/09 Systemtap‐CernSchoolofCompu9ng‐MalteNuhn 17