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Architecture of Computing Systems (Lecture Notes in Computer ...

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170 M.F. Dolz et al.<br />

On the other hand, 73.3% <strong>of</strong> the jobs was executed on group 1, 0% requested<br />

group 2, 16.99% requested group 3, and 9.7% requested the Altix server.<br />

– The average execution time <strong>of</strong> the jobs was 1 day, 2 hours and 53 m<strong>in</strong>utes.<br />

We evaluated the follow<strong>in</strong>g policies:<br />

– No Policy (NP): This configuration represents a conventional cluster without<br />

the energy sav<strong>in</strong>g module on which nodes are permanently active.<br />

– Policy 1 (P1):<br />

• Activation/deactivation conditions:<br />

1. Job without resources (Turn on).<br />

2. Idle time <strong>of</strong> a node (Turn <strong>of</strong>f): Max. idle time: 60 seconds.<br />

• Node selection algorithm: Ordered.<br />

• Strict level: No strict.<br />

– Policy 2 (P2): This is the same configuration as P1, except for the Strict<br />

level which is changed from “No strict” to “Strict” level.<br />

– Policy 3 (P3): This is the same configuration as P1, except for the Strict<br />

level which is changed from “No strict” to “Strict and sequential” level.<br />

Table 1 reports the follow<strong>in</strong>g results obta<strong>in</strong>ed with the simulator:<br />

–Latency: Average time s<strong>in</strong>ce jobs are submitted till their execution is completed.<br />

This value thus <strong>in</strong>cludes the time a job is enqueued as well as its<br />

execution time.<br />

– Power on time (%): Average fraction <strong>of</strong> the total time that the nodes <strong>of</strong><br />

the cluster rema<strong>in</strong> turned on.<br />

–Totaltime: Elapsed time s<strong>in</strong>ce the first job is submitted till the last job<br />

completes its execution.<br />

– Total consumption: Total consumption <strong>in</strong> MWatts-hour (MWh). (We have<br />

considered that a node consumes on average 250 Watts/hour.)<br />

The results <strong>in</strong> the table show that the NP policy, where all the nodes are powered<br />

on all the time, yields an average response time (latency) per job over 339 h,<br />

and consumes consumes 65.37 MWh to execute the 10,415 jobs. The application<br />

<strong>of</strong> policy P1 (“No strict” level) roughly <strong>in</strong>creases the job latency to 461 h, but<br />

now the percentage <strong>of</strong> time that nodes are powered on is only 42.9%, and the<br />

power consumption is reduced to 29.51 MWh.<br />

Table 1. Execution time and energy sav<strong>in</strong>gs obta<strong>in</strong>ed for different policies<br />

Policy Latency Power on Total time Total<br />

time consumption<br />

NP 339 h, 44 m, 18 s 100.0% 4,022 h, 39 m, 50 s 65.37<br />

P1 461 h, 54 m, 0 s 42.9% 4,022 h, 49 m, 15 s 29.51<br />

P2 12,387 h, 56 m, 34 s 5.8% 29,962 h, 2 m, 41 s 46.50<br />

P3 36,556 h, 28 m, 9 s 2.2% 86,712 h, 51 m, 31 s 85.73

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