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Latency (µs)<br />

30<br />

25<br />

20<br />

15<br />

10<br />

5<br />

0<br />

0 s<br />

Autonomic Workload Management for Multi-core Processor <strong>Systems</strong> 59<br />

4 ms<br />

8 ms<br />

12 ms<br />

Fig. 7. Packet latency across various traffic scenarios<br />

16 ms<br />

20 ms<br />

24 ms<br />

28 ms<br />

Static Opt.<br />

DVFS R2C<br />

Auto Global<br />

system-wide average frequency which is larger than that <strong>of</strong> the pipel<strong>in</strong>ed and autonomic<br />

systems, which split the load across all three CPUs. This also <strong>in</strong>creases the<br />

delta value for workload (recall equation 4 from section 2.3.3) <strong>of</strong> the run-tocompletion<br />

system, which further worsens the system’s objective value.<br />

Figure 7 shows the impact that the autonomic enhancements have on the packet latency,<br />

a global system behavior <strong>of</strong> which the autonomic evaluator is neither aware,<br />

nor has a direct <strong>in</strong>fluence over. At the beg<strong>in</strong>n<strong>in</strong>g <strong>of</strong> each burst, the packet latency <strong>of</strong><br />

the autonomic system shows a brief <strong>in</strong>crease as the system adapts itself to the change<br />

<strong>in</strong> workload. Thereafter, the autonomic enhancements optimize the system such that<br />

the packet latency rema<strong>in</strong>s nearly constant at 10 µs across all traffic scenarios. Dur<strong>in</strong>g<br />

the sixth burst, where the packet latency rises slightly above this value, the autonomic<br />

system cont<strong>in</strong>ues to search for a more preferable system configuration, but is <strong>in</strong>terrupted<br />

prior to f<strong>in</strong>d<strong>in</strong>g one by the follow<strong>in</strong>g burst.<br />

4 Conclusion and Future Work<br />

In this paper, we have demonstrated the applicability <strong>of</strong> self-organization concepts<br />

and HW-based mach<strong>in</strong>e learn<strong>in</strong>g techniques for the run-time b<strong>in</strong>d<strong>in</strong>g <strong>of</strong> SW tasks to<br />

homogeneous multi-core processors. SW application developers can follow established<br />

design flows for functional partition<strong>in</strong>g <strong>of</strong> applications <strong>in</strong>to sub-functions<br />

(tasks) without be<strong>in</strong>g forced to consider the underly<strong>in</strong>g parallel MP-SoC HW architecture.<br />

LCT-based hardware evaluators take care <strong>of</strong> balanc<strong>in</strong>g CPU workloads<br />

among available process<strong>in</strong>g resources, without requir<strong>in</strong>g a special programm<strong>in</strong>g language<br />

or fundamental OS modifications. It has been shown that the autonomic system<br />

is capable <strong>of</strong> parameteriz<strong>in</strong>g a pipel<strong>in</strong>ed architecture so that it performs similarly to a<br />

comparable, DVFS-enabled run to completion architecture. The result<strong>in</strong>g system<br />

comb<strong>in</strong>es the benefits <strong>of</strong> both architecture types, while delegat<strong>in</strong>g solution <strong>of</strong> the<br />

disadvantages, most notably the difficulty <strong>of</strong> efficiently distribut<strong>in</strong>g the workload <strong>of</strong> a<br />

pipel<strong>in</strong>ed system, to the autonomic layer.<br />

Further work is planned for the completion <strong>of</strong> an FPGA hardware prototype to verify<br />

the presented simulation results <strong>in</strong> a functional MP-SoC, and to show that resource<br />

overheads are as small as prelim<strong>in</strong>ary synthesis results seem to <strong>in</strong>dicate. We also plan<br />

to fully <strong>in</strong>vestigate the stability <strong>of</strong> the result<strong>in</strong>g system, although our simulations so

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