1. Predicting the Quality of Service of a Peer-to-Peer Desktop Grid Marcus Carvalho OurGrid Project Federal University of Campina Grande, Brazil

5. Prediction of P2P Grid’s Quality of Service How many resources will be available for a peer in a P2P Desktop Grid at future instants of time? 4 Problem Predicting the QoS of a P2P Grid We propose a prediction model based on system behaviour and grid information

6. Network of Favours A = 1 C = 0 B = 2 C = 4 A = 0 C = 0 Predicting the QoS of a P2P Grid B = 1 C = 2 Peer A Peer B Resources proportionally shared A = 0 B = 0 A = 2 B = 0 Peer C Task Queue Balances Task Resource 5

7. Network of Favours A = 0 C = 2 B = 0 C = 0 A = 0 C = 0 B = 0 C = 2 Peer A Peer B Resources equally shared A = 0 B = 0 Peer C Task Queue Balances Task Resource 6 Predicting the QoS of a P2P Grid

8. Predicting the QoS of a P2P Grid 7 Prediction model Resources equally shared Resources proportionally shared Proportion of local peer’s balance for peer d Estimation of resources obtained from a peer d attime t = We need to estimate the functions’ values for a prediction target time tp in the future myBalanced(t)othersBalancedt+myBalanced(t) ∙ idleResourcesdt idleResourcesd(t)consumers (t) If any consumer has positive balance tc otherwise tp2 tp3 tp1

9. We assume that information at the current time tc is available Estimating local peer’s balance update myBalancedtc is known myBalancedt=myBalancedt−1−obtaineddestimatet−1 for t≥tc We estimate the other functions as constant idleResourcesdt=idleResourcesd(tc) othersBalancedt=othersBalanced(tc) consumerst=consumers(tc) Predicting the QoS of a P2P Grid 8 Prediction model tp2 tp3 tp1 tc

10. Obtained Ratio OR= obtainedrequested Estimated Ratio ER=min⁡( estimatedrequested ,100% ) Prediction Error 𝜉 = ER − OR Predicting the QoS of a P2P Grid 9 Evaluation - Metrics

11. Workload NorduGrid trace (Grid Workload Archive) 6 months 40 sites (peers) Prediction target times (tp) All consumption windows of each peer Δtp = {0, 2, 4, 6, ..., te−tc} minutes Predicting the QoS of a P2P Grid 10 Evaluation - Scenarios tc te Δtp3 Δtp1 tp3 tp1 tp2 Δtp2

12. Resources per peer r = {20, 40, 60, 80} Same # resources for all peers OR (obtainedrequested) variation over time: Predicting the QoS of a P2P Grid 11 Evaluation - Scenarios resources per peer r = 20 resources per peer r =40 resources per peer r =60 resources per peer r =80

13. Predicting the QoS of a P2P Grid 12 Prediction Results resources per peer r = 20 resources per peer r =40 resources per peer r =60 resources per peer r =80

14. Predicting the QoS of a P2P Grid 13 Prediction Results

15. P2P Desktop Grids have volatile resources and a competitive environment Uncertainty on the Quality of Service It is possible to have good estimations on the number of resources available for a peer in the grid Predictions based on system behaviour and grid information Predicting the QoS of a P2P Grid 14 Conclusion

16. Prediction based on partial and inaccurate grid information Explicitly model the idleness of resources Evaluation with different workloads Predicting the QoS of a P2P Grid 15 Future work

17. Predicting the QoS of a P2P Grid 16 Thank you! Questions ? Marcus Carvalho marcus@lsd.ufcg.edu.br http://www.ourgrid.org