Commit 61fa30d37740a434e8de1b48f6e9a40903e97443

Authored by Geoffrey Challen
1 parent 5b8d931f

Mine.

Showing 1 changed file with 26 additions and 49 deletions
usage.tex
@@ -2,33 +2,17 @@ @@ -2,33 +2,17 @@
2 \label{sec-usage} 2 \label{sec-usage}
3 3
4 To motivate the need for a value measure, we return to the questions posed in 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 All smartphone users intuitively realize that smartphone apps differ in 12 All smartphone users intuitively realize that smartphone apps differ in
26 value---an email client, for example, is probably more valuable than a app 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 To argue that this is possible we present two experiments that elucidate 17 To argue that this is possible we present two experiments that elucidate
34 smartphone app value in the form of both ordinal and cardinal utilities, 18 smartphone app value in the form of both ordinal and cardinal utilities,
@@ -49,19 +33,15 @@ battery percentages to each app you use. @@ -49,19 +33,15 @@ battery percentages to each app you use.
49 % 33 %
50 We plan to engage smartphone users in studies to explore in more detail which 34 We plan to engage smartphone users in studies to explore in more detail which
51 of these approaches is more effective, comparing them by comparing users' 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 In either case, we believe that these experiments do suggest the existence of 46 In either case, we believe that these experiments do suggest the existence of
67 quantifiable value for smartphone apps. We are not claiming, however, that 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 @@ -90,15 +70,14 @@ consumption. Unless it is terribly written, the chat client will consume less
90 energy. But this does not mean that it is efficient, or that the 70 energy. But this does not mean that it is efficient, or that the
91 videoconferencing app is not. Ultimately, all the energy consumption 71 videoconferencing app is not. Ultimately, all the energy consumption
92 comparison truly reveals is that the two apps do different things---which we 72 comparison truly reveals is that the two apps do different things---which we
93 -knew. 73 +already knew.
94 74
95 Using energy consumption alone even makes apples-to-apples of the same app 75 Using energy consumption alone even makes apples-to-apples of the same app
96 difficult. Given an app that consumes twice as much energy on Alice's 76 difficult. Given an app that consumes twice as much energy on Alice's
97 smartphone than on Bob's, the question of why is left unanswered by pure 77 smartphone than on Bob's, the question of why is left unanswered by pure
98 energy measures. Even if usage time can be used to normalize the comparison 78 energy measures. Even if usage time can be used to normalize the comparison
99 to the power consumed, power consumption alone cannot incorporate differences 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 By computing value and, thus, energy efficiency, we can overcome these 82 By computing value and, thus, energy efficiency, we can overcome these
104 weaknesses. A value measure should allow us to compare the efficiency of two 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 @@ -108,10 +87,10 @@ video players. Comparisons within the same app category should allow users to
108 select the most efficient email client or web browser. Aggregating results 87 select the most efficient email client or web browser. Aggregating results
109 over all users, differences in app energy efficiency should reflect how well 88 over all users, differences in app energy efficiency should reflect how well
110 the app is written and how well it predicts and adapts to users, not just 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 \subsection{Evaluating App Changes} 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 @@ -150,9 +129,9 @@ allocates a rate to each app and enforces that rate by slowing or stopping
150 the app when it exceeds its 129 the app when it exceeds its
151 allocation~\cite{odyssey-osr99,cinder-eurosys11,Zeng:2003,pixie-sensys08}. 130 allocation~\cite{odyssey-osr99,cinder-eurosys11,Zeng:2003,pixie-sensys08}.
152 However, all of these previous efforts have ignored the critical question of 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 A measure of value can be used alone or in conjunction with energy consumption 136 A measure of value can be used alone or in conjunction with energy consumption
158 to help prioritize limited energy resources. The simplest approach is to 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. @@ -186,10 +165,8 @@ inputs, requiring that it be calculable given data from a single user.
186 app generate value and what parts do not. 165 app generate value and what parts do not.
187 166
188 \item It should be able to be efficiently computed to not overly consume the 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 \item It should be derived with little to no input from the user. 170 \item It should be derived with little to no input from the user.
192 171
193 \end{itemize} 172 \end{itemize}
194 -%  
195 -We continue by discussing possible inputs to such a metric.