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GWpilot: a personal pilot system

This paper discusses the common problems in grid computation and introduces GWpilot, a personal pilot system that offers advantages such as reducing grid complexity, improving task dispatching, and increasing compatibility. The implementation and features of GWpilot are also described, along with its suitability for distributed applications.

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GWpilot: a personal pilot system

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  1. GWpilot: a personal pilot system A.J. Rubio-Montero, E. Huedo and R. Mayo-García EGI Technical Forum 2012 Prague – 20 Sep 2012

  2. Outline • Common problems in Grid computation • Pilot Jobs • GWpilot • Advantages • Utilisation • Design and improvements • Suitability • DKEsG • Revision • Description of the calculation performed • Performance measurements • Some results • Conclusions EGI TF 2012 – Prague, 20 Sep 2012

  3. Common problems in Grid Computation • Variable overheads: queue waiting times, overload... • Variable error rate: connection cuts, jobs arbitrary aborted… • Diverse configurations: complexity, unexpected types of WN… • To increase performance by means of scheduling, the resources must be completely characterised, but it is impossible with generic middleware: • Design defects: GLUE specification is incomplete: no broadband, latency, queue policy, average waiting time, resource profile… • Miss-configurations and lacks of maintenance • Solutions • Self-scheduling • Models • Heuristics • Statistics • Pilot jobs EGI TF 2012 – Prague, 20 Sep 2012

  4. Pilot Factory CE pilot pilot LRMS queue Pilot Jobs: basics Coordinator Server task task task task task monitoring pilot task task SLOT APPROPIATION task task task pilot EGI TF 2012 – Prague, 20 Sep 2012

  5. Pilot jobs: benefits • Reduce the Grid complexity: • direct use and characterization of assigned WNs • direct monitoring user tasks. • Fix task dispatching overheads • remove the waiting time in remote queues • remove middleware overheads and errors (CREAM,GRAM) • Reduce task error rate: middleware, hardware or connectivity • Increase compatibility • creating special configurations • Implementing legacy communication protocols • Allows the implementation of advanced scheduling techniques EGI TF 2012 – Prague, 20 Sep 2012

  6. Pilot Jobs: Implementations • Centralized frameworks: daunting maintenance, deployment and customization. • AliEn and PanDa (suitable for HEP users) • DIRAC • glideinWMS • EDGeS (XtremWeb) and GridBot (BOINC) • Application-oriented: mono-user, mono-application. • DIANE • They are not exploiting all the scheduling advantages provided by pilot jobs or they lack compatibility or adaptability aspects • Alternative  GWpilot EGI TF 2012 – Prague, 20 Sep 2012

  7. GWpilot: features • Easy-to-install and standalone from remote middleware • Highly customizable and tuneable, even by unskilled users • Multi-user with fair-share policies • Compatible with previously ported applications • Interoperable with diverse Grid infrastructures • Lightweight and scalable, achieving nearly optimal performance • Advanced scheduling policies for any kind of tasks EGI TF 2012 – Prague, 20 Sep 2012

  8. GWpilot: simplicity of use and configuration • GWpilot makes the use of pilot jobs automatic and unattended both to users and developers: # cat ls_template.jt EXECUTABLE = /bin/ls STDOUT_FILE = logs/ls.out.${ARCH}.${JOB_ID} STDERR_FILE = logs/ls.err.${ARCH}.${JOB_ID} REQUIREMENTS = LRMS_NAME = "jobmanager-pilot" RANK = CPU_MHZ # gwsubmit -t ls_template.jt Users have only to fix this requirement in their tasks • Usual configuration parameters • maximum of submitted pilots • dispatching suspension timeout (maximum time spent at remote LRMS) • pilot pulling interval against GWpilot and number of retries # cat gwd.conf … IM_MAD = pilot_im:gw_im_mad_pilot::dummy:pilot_em EM_MAD = pilot_em:gw_em_mad_pilot:-m 550 –t 18000 -i 45 -f 20 :rsl_nsh … EGI TF 2012 – Prague, 20 Sep 2012

  9. HTTPS pull GWpilot: integrated into GridWay metascheduler task task task Applications pilots More accurate estimation of free slots BES JSDL CLI DRMAA GWpilot Factory Scheduler GridWay Core Allows submitting a % more pilots than the estimated free slots MSD2 GLUE CREAM GRAM GWpilot Server BDII CREAM CE site-BDII pilot site-BDII GLOBUS CE task pilot EGI TF 2012 – Prague, 20 Sep 2012

  10. GWpilot: suitability for distributed applications • Could give a boost to your computational challenges !!! • Legacy applications previously ported to GridWay or to DRMAA/BES/JSDL standards can directly benefit from GWpilot. • Examples: • Truba/MaRaTra • VMEC • ISDEP • FAFNER-2 • gGEM • DKEsG : Drift Kinetic Equation solver for Grid EGI TF 2012 – Prague, 20 Sep 2012

  11. DKEsG: calculating NC transport of Fusion devices Fluxes through the surfaces generated by the magnetic field lines: NC transport coefficients The DKEsG Workflow*1 Updated with Spong’s DKEs code*2 DRMAA-enabled producer-consumer workflow: chunking tasks and polling time for BoT states are customizable *1 A. J. Rubio-Montero et al. “Drift Kinetic Equation Solver for Grid (DKEsG),” IEEE Trans.Plasma Sci., 38( 9). 2010. *2 D. A. Spong, “Generation and damping of neoclassical plasma flows in stellarators,” Phys. Plasmas, 12(5), 2005. EGI TF 2012 – Prague, 20 Sep 2012

  12. Experiment: DKEsG parameter scan with the TJ-II standard configuration r[2…141] X EFIELD[-250…250:10] X CMUL[(1…9)10(-7…0)] = 514,080independent tasks (1 to 12 min proportional to radius) 420 tasks 5 tasks X BoT 103,236 independent BoTs 6.58 years on Intel Xeon X5365 3GHz (64bit) EGI TF 2012 – Prague, 20 Sep 2012

  13. Resources used and configuration bounds Max pilots submitted by GWpilot • DKEsG only submits 500 BoTs • BoT Susp. timeout: 60 secs Used for submitting pilots GISELA infrastructure (prod.vo.eu-eela.eu) Discarded 32bits, duplicate and CERN resources. • Limited to 100 jobs per resource • queues overloaded with 15% more pilots • suspension timeout: 5 hours • Other configuration parameters: • Pilot pulling interval : 45 seconds with 20 retries. • DKEsG polling time: 15 secs. • Resources are ranked/prioritised based on CPU speed EGI TF 2012 – Prague, 20 Sep 2012

  14. Experiment: measured computational results Pilots die when a BoT is running inside Suspended BoTs because they have been assigned to death pilots Only 0.4% failing BoTs Many overloaded sites 62% failing grid jobs Makespan: 94 h: 27 m: 31 s. 610 times fasterthan sequential Total time wasted at remote queues: 1 year and 20 days. Not appreciable by the user. EGI TF 2012 – Prague, 20 Sep 2012

  15. Experiment: turnaround measurements The number of available pilots are lower than 500 DKEsG cannot supply enough BoTs Pilot overhead is always between 41-43 secs  Scalability of GWpilot Accumulated turnaround overhead is only 6.21%. If only GridWay were used the resultant one* would be 61.48% * A.J. Rubio-Montero et al, “Executions of a Drift Kinetic Ecuation solver on Grid,”in PDP 2010, Pisa, Italy. EGI TF 2012 – Prague, 20 Sep 2012

  16. Plasma results: bootstrap current (D13) of the outer radial plasma position in TJ-II (negative polarization) This surface needs: 3672 DKEsG-Mono tasks = 663 CPU hours consumed from the Grid Boostrap current tends to zero As expected, the coefficients are even in the electric field. • The collisionless asymptotic value (which depends on the configuration) is recovered. • Larger uncertainties appear in the long mean free path regime. EGI TF 2012 – Prague, 20 Sep 2012

  17. Plasma results: normalized NC transport coefficients (L33) from the resistivity enhancement (positive polarization) • CMUL and EFIELD parameters decrease monotonically as K increases. • By solving the integration in K, there is a continuous reutilization of the data included in the database EGI TF 2012 – Prague, 20 Sep 2012

  18. Conclusions • Summary • GWpilot is suitable to easily improve the performance of several kinds of fusion codes. • New features have been implemented in GridWay and DKEsG. • DKEsG execution shows impressive improvements in terms of makespan and turnaround. • Future work • Continue the DKEsG calculations in order to build an extensive database for several fusion devices that allows the user to read the monoenergetic coefficients and to obtain the final fluxes without performing again the calculations. • We are evaluating GWpilot with other applications from other scientific areas. • More information at: • www.ciemat.es/portal.do?IDR=343&TR=C • www.gridway.org EGI TF 2012 – Prague, 20 Sep 2012

  19. Thanks for your attention EGI TF 2012 – Prague, 20 Sep 2012

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