Enabling Grids for E- sciencE EGEE and gLite are registered trademarks EGEE-III INFSO-RI-222667...

Enabling Grids for E-sciencE

www.eu-egee.org

EGEE and gLite are registered trademarks EGEE-III INFSO-RI-222667

Analysis of Overhead and waiting times in the EGEE Production Grids

Max BergerThomas ZangerlThomas FahringerUniversity of Innsbruck


EGEE-III INFSO-RI-222667

Overview

• EGEE• Definitions• Scheduling Latency• Information Service Latency• Conclusions



EGEE

• EGEE: Enabling Grids for E-SciencE• Largest Grid Infrastructure in the World• 140 Institutions, 300 Sites, 50 Countries,

10.000 users, 80.000 CPU cores• Production Grid Infrastructure• Uses the gLite middleware• Organized in Virtual Organizations (VO)



VOCE

• VOCE: VO for Central Europe• Part of the EGEE Project• 18 Sites participate• “Liberal” Usage Policy

– Users must be from the CE Region– Any Research can be done



Definitions

• Scheduling LatencyDelay between Job Submission and actual execution in seconds

• Information Service (IS) LatencyDelay between actual occurrence of an event and its notification for the user



Experiment Description

• Test jobs where submitted to VOCE VO• Between Aug 08 and Oct 08• Approx. every 30 minutes• Measured status change notifications• Real status changes through callbacks• Jobs where canceled after 45 mins

scheduling time



Scheduling Latency / Week



Scheduling Latency / Day



Scheduling Latency (cont.)

• Mean: 121 seconds• Median: 91 seconds• Most of the time short, but exceptions can take a very

long time• No significant changes over the week

– Suggested “Weekend-Effect” was not provable

• No significant changes over the day– The Grid is in use all the time

• Clustering of values• This value is much lower than values shown in related

work!– Real execution start vs. notified execution start



Scheduling Latency Histogram



Scheduling Latency / Site



Information Service Latency



IS Latency (cont.)

• Mean: 208 seconds• Median: 198 seconds• IS is organized in layers• Each layer polls the underlying layer• Polling interval defines time needed



IS Latency (cont.)



Conclusions

• Production Grid are different from Research Grids!• Scheduling Latency is not predictable

• Depends on the Site

• Additional overhead in the Information Service• IS Overhead > Scheduling Latency• Information is relevant for deciding

• Size of workload• Scheduling of activities in workflows

Enabling Grids for E- sciencE EGEE and gLite are registered trademarks EGEE-III INFSO-RI-222667...

Documents

Transcript of Enabling Grids for E- sciencE EGEE and gLite are registered trademarks EGEE-III INFSO-RI-222667...