Commit 61fa30d37740a434e8de1b48f6e9a40903e97443
1 parent
5b8d931f
Mine.
Showing
1 changed file
with
26 additions
and
49 deletions
usage.tex
| ... | ... | @@ -2,33 +2,17 @@ |
| 2 | 2 | \label{sec-usage} |
| 3 | 3 | |
| 4 | 4 | To motivate the need for a value measure, we return to the questions posed in |
| 5 | -the introduction. We explore each in more depth, providing a more detailed | |
| 6 | -description of how a value measure could be used. These use cases also help | |
| 7 | -us develop requirements for our metric, which are summarized at the end of | |
| 8 | -this section. We begin by exploring the basic question at the heart of the | |
| 9 | -problem: what is the value delivered by an app? | |
| 5 | +the introduction and explore each in more depth. These use cases also help us | |
| 6 | +develop requirements for our measure, which are summarized at the end of this | |
| 7 | +section. We begin by exploring the basic question at the heart of the | |
| 8 | +problem: what is the value of an app? | |
| 10 | 9 | |
| 11 | -\subsection{What is Value?} | |
| 12 | - | |
| 13 | -\begin{comment} | |
| 14 | - | |
| 15 | -\begin{quote} | |
| 16 | -I shall not today attempt further to define the kinds of material I | |
| 17 | -understand to be embraced within that shorthand description; and perhaps I | |
| 18 | -could never succeed in intelligibly doing so. But I know it when I see it, | |
| 19 | -and the motion picture involved in this case is not that.\\ | |
| 20 | ----Justice Potter Stewart~\cite{jacobellisvohio}. | |
| 21 | -\end{quote} | |
| 22 | - | |
| 23 | -\end{comment} | |
| 10 | +\subsection{What is App Value?} | |
| 24 | 11 | |
| 25 | 12 | All smartphone users intuitively realize that smartphone apps differ in |
| 26 | 13 | value---an email client, for example, is probably more valuable than a app |
| 27 | -that makes farting sounds, and a chat client is probably more valuable than a | |
| 28 | -chat client that only sends the message ``yo''. In Supreme Court Justice | |
| 29 | -Potter Steward's famous formulation, they know value when they see it. But is | |
| 30 | -it possible to quantify these subjective distinctions and produce a value | |
| 31 | -measure? | |
| 14 | +that makes farting sounds. But is it possible to quantify these subjective | |
| 15 | +distinctions and produce a value measure? | |
| 32 | 16 | |
| 33 | 17 | To argue that this is possible we present two experiments that elucidate |
| 34 | 18 | smartphone app value in the form of both ordinal and cardinal utilities, |
| ... | ... | @@ -49,19 +33,15 @@ battery percentages to each app you use. |
| 49 | 33 | % |
| 50 | 34 | We plan to engage smartphone users in studies to explore in more detail which |
| 51 | 35 | of these approaches is more effective, comparing them by comparing users' |
| 52 | -levels of satisfaction under each scenario. As an alternate formulation of | |
| 53 | -the second experiment to make it more similar to the first, the adversary | |
| 54 | -could remove the apps consuming the least energy up to a given target. | |
| 55 | - | |
| 56 | -For our value measure we are hopeful that users will prove capable of | |
| 57 | -assigning cardinal utilities to apps---as in the second experiment---since | |
| 58 | -this matches most directly with our proposed value measure and could provide | |
| 59 | -ground truth for a value measure computed automatically. The second | |
| 60 | -experiment also engages users directly in the task of allocating energy, | |
| 61 | -which is one way that a value measure could be used. However, if ordinal | |
| 62 | -utilities prove more intuitive we can still compare the ordering generated by | |
| 63 | -our value metric with the ordering generated by users, although the specific | |
| 64 | -values of the measure will still require justification. | |
| 36 | +levels of satisfaction under each scenario. For our value measure we are | |
| 37 | +hopeful that users will prove capable of assigning cardinal utilities to | |
| 38 | +apps---as in the second experiment---since this matches most directly with | |
| 39 | +our proposed value measure and could provide ground truth for a value measure | |
| 40 | +computed automatically. The second experiment also engages users directly in | |
| 41 | +the task of allocating energy, which is one way that a value measure could be | |
| 42 | +used. However, if ordinal utilities prove more intuitive we can still compare | |
| 43 | +the ordering generated by our measure with the ordering generated by users, | |
| 44 | +although the values of the measure will still require justification. | |
| 65 | 45 | |
| 66 | 46 | In either case, we believe that these experiments do suggest the existence of |
| 67 | 47 | quantifiable value for smartphone apps. We are not claiming, however, that |
| ... | ... | @@ -90,15 +70,14 @@ consumption. Unless it is terribly written, the chat client will consume less |
| 90 | 70 | energy. But this does not mean that it is efficient, or that the |
| 91 | 71 | videoconferencing app is not. Ultimately, all the energy consumption |
| 92 | 72 | comparison truly reveals is that the two apps do different things---which we |
| 93 | -knew. | |
| 73 | +already knew. | |
| 94 | 74 | |
| 95 | 75 | Using energy consumption alone even makes apples-to-apples of the same app |
| 96 | 76 | difficult. Given an app that consumes twice as much energy on Alice's |
| 97 | 77 | smartphone than on Bob's, the question of why is left unanswered by pure |
| 98 | 78 | energy measures. Even if usage time can be used to normalize the comparison |
| 99 | 79 | to the power consumed, power consumption alone cannot incorporate differences |
| 100 | -due to the different app features used by Alice and Bob or the different ways | |
| 101 | -that they have configured the app. | |
| 80 | +due to the different app features or configurations used by Alice and Bob. | |
| 102 | 81 | |
| 103 | 82 | By computing value and, thus, energy efficiency, we can overcome these |
| 104 | 83 | weaknesses. A value measure should allow us to compare the efficiency of two |
| ... | ... | @@ -108,10 +87,10 @@ video players. Comparisons within the same app category should allow users to |
| 108 | 87 | select the most efficient email client or web browser. Aggregating results |
| 109 | 88 | over all users, differences in app energy efficiency should reflect how well |
| 110 | 89 | the app is written and how well it predicts and adapts to users, not just |
| 111 | -differences in the core features it provides. And when comparing two users | |
| 112 | -using the same app, differences in energy efficiency should reflect different | |
| 113 | -configurations or differences in how efficiently at app provides certain | |
| 114 | -features, not just that one user is using one feature and another is not. | |
| 90 | +differences in the core features it provides. When comparing two users using | |
| 91 | +the same app, differences in efficiency should reflect different | |
| 92 | +configurations or differences in how efficiently the app provides certain | |
| 93 | +features. | |
| 115 | 94 | |
| 116 | 95 | \subsection{Evaluating App Changes} |
| 117 | 96 | |
| ... | ... | @@ -150,9 +129,9 @@ allocates a rate to each app and enforces that rate by slowing or stopping |
| 150 | 129 | the app when it exceeds its |
| 151 | 130 | allocation~\cite{odyssey-osr99,cinder-eurosys11,Zeng:2003,pixie-sensys08}. |
| 152 | 131 | However, all of these previous efforts have ignored the critical question of |
| 153 | -\textbf{how rates should be set}. No matter how effective the enforcement | |
| 154 | -mechanisms are, systems that rely on rates will fail if they provide the same | |
| 155 | -rate to Skype and Snapchat, or to a very efficient app and an energy virus. | |
| 132 | +how rates should be set. No matter how effective the enforcement mechanisms | |
| 133 | +are, systems that rely on rates will fail if they provide the same rate to | |
| 134 | +Skype and Snapchat, or to a very efficient app and an energy virus. | |
| 156 | 135 | |
| 157 | 136 | A measure of value can be used alone or in conjunction with energy consumption |
| 158 | 137 | to help prioritize limited energy resources. The simplest approach is to |
| ... | ... | @@ -186,10 +165,8 @@ inputs, requiring that it be calculable given data from a single user. |
| 186 | 165 | app generate value and what parts do not. |
| 187 | 166 | |
| 188 | 167 | \item It should be able to be efficiently computed to not overly consume the |
| 189 | -very resource that it is designed to help manage. | |
| 168 | +resources that it is designed to help manage. | |
| 190 | 169 | |
| 191 | 170 | \item It should be derived with little to no input from the user. |
| 192 | 171 | |
| 193 | 172 | \end{itemize} |
| 194 | -% | |
| 195 | -We continue by discussing possible inputs to such a metric. | ... | ... |