Feasibility Study
Eat All You Can in an All-You-Can-Eat Buffet
Ratul Mahajan Jitendra Padhye Ramya Raghavendra Brian Zill
Microsoft Research
Abstract — In contrast to the efficiency-centric designs that are more prevalent today, we advocate a view of system design based on a holistic view of available resources. This view is embodied in what we call the Buffet principle: continue using additional resources as long as the marginal benefit is more than the marginal cost of using the resources. We illustrate through several examples how this seemingly obvious principle is not adhered to by many common designs and how its application can lead to qualitatively different and better performing designs. We also discuss the broad considerations that apply to designing systems that use the Buffet principle.
1. INTRODUCTION
Alice is hungry and walks into a restaurant that is serving an all-you-can-eat buffet. She wants to eat enough food so that she can avoid hunger until the next meal. Should she eat based on expected time until the next meal, or should she eat as much as she can? In this context, the second strategy is clearly superior. With the first strategy, any misestimation in the time until the next meal (or a faster than anticipated digestive rate due to increased activity levels) would lead to hunger. The second strategy provides the best possible protection against hunger that is limited only by the space in Alice’s stomach. And it represents no additional cost over the first strategy. Surprisingly, system design often follows the first strategy today. For instance, consider the task of adding FEC (forward error correction) bits to transmissions over a noisy channel such as wireless. In current designs, the number of added bits tends to be a function of the anticipated bit error rate [2, 4, 18], and independent of the available spectrum resources. This method protects against packet loss as long as the bit error rate is below the anticipated rate, but fails when it is higher or
Ratul Mahajan Jitendra Padhye Ramya Raghavendra Brian Zill
Microsoft Research
Abstract — In contrast to the efficiency-centric designs that are more prevalent today, we advocate a view of system design based on a holistic view of available resources. This view is embodied in what we call the Buffet principle: continue using additional resources as long as the marginal benefit is more than the marginal cost of using the resources. We illustrate through several examples how this seemingly obvious principle is not adhered to by many common designs and how its application can lead to qualitatively different and better performing designs. We also discuss the broad considerations that apply to designing systems that use the Buffet principle.
1. INTRODUCTION
Alice is hungry and walks into a restaurant that is serving an all-you-can-eat buffet. She wants to eat enough food so that she can avoid hunger until the next meal. Should she eat based on expected time until the next meal, or should she eat as much as she can? In this context, the second strategy is clearly superior. With the first strategy, any misestimation in the time until the next meal (or a faster than anticipated digestive rate due to increased activity levels) would lead to hunger. The second strategy provides the best possible protection against hunger that is limited only by the space in Alice’s stomach. And it represents no additional cost over the first strategy. Surprisingly, system design often follows the first strategy today. For instance, consider the task of adding FEC (forward error correction) bits to transmissions over a noisy channel such as wireless. In current designs, the number of added bits tends to be a function of the anticipated bit error rate [2, 4, 18], and independent of the available spectrum resources. This method protects against packet loss as long as the bit error rate is below the anticipated rate, but fails when it is higher or
References: 6. CONCLUSIONS We proposed a different perspective on system design. This perspective advocates a more holistic view of available resources rather than blindly focusing on their efficient use. It can summarized using the Buffet principle which states that we should continue using additional resources as long as the marginal benefit is more than the marginal cost of using the resources. Instead of being 6