WebCore: Architectural Support for Mobile Web Browsing Yuhao Zhu, Vijay Janapa Reddi Department of Electrical and Computer Engineering The University of Texas at Austin ISCA MainTalk — June 18th, 2014
The Fundamental Challenges How to achieve high performance with low energy? 4 Achieving High Performance Demanded by End-User Conserving Energy Due to Limited Battery Capacity Conflicting requirements
The Fundamental Challenges How to achieve high performance with low energy? 4 Achieving High Performance Demanded by End-User Conserving Energy Due to Limited Battery Capacity Conflicting requirements A mobile architecture
The Fundamental Challenges How to achieve high performance with low energy? 4 Achieving High Performance Demanded by End-User Conserving Energy Due to Limited Battery Capacity Conflicting requirements A mobile architecture WebCore:
Agenda of Today’s Talk ▸Motivation of our work: energy-efficiency of the mobile Web ▸How does WebCore improve the energy-efficiency? ▹Customization ▹Specialization 7
Agenda of Today’s Talk ▸Motivation of our work: energy-efficiency of the mobile Web ▸How does WebCore improve the energy-efficiency? ▹Customization ▹Specialization ▸Evaluation Results 7
Agenda of Today’s Talk ▸Motivation of our work: energy-efficiency of the mobile Web ▸How does WebCore improve the energy-efficiency? ▹Customization ▹Specialization ▸Evaluation Results ▸Related Work 7
Agenda of Today’s Talk ▸Motivation of our work: energy-efficiency of the mobile Web ▸How does WebCore improve the energy-efficiency? ▹Customization ▹Specialization ▸Evaluation Results ▸Related Work 8
▸Why customization?!? ▸What is a proper general purpose baseline architecture? ▹Out-of-order (Silvermont, A15) or in-order (Saltwell, A7)? Customization: Find the Ideal General Purpose Baseline Architecture
▸Why customization?!? ▸What is a proper general purpose baseline architecture? ▹Out-of-order (Silvermont, A15) or in-order (Saltwell, A7)? ▹Are existing general purpose mobile designs ideal? Customization: Find the Ideal General Purpose Baseline Architecture
▸Why customization?!? ▸What is a proper general purpose baseline architecture? ▹Out-of-order (Silvermont, A15) or in-order (Saltwell, A7)? ▹Are existing general purpose mobile designs ideal? ▸Exhaustive design space exploration Customization: Find the Ideal General Purpose Baseline Architecture
▸Why customization?!? ▸What is a proper general purpose baseline architecture? ▹Out-of-order (Silvermont, A15) or in-order (Saltwell, A7)? ▹Are existing general purpose mobile designs ideal? ▸Exhaustive design space exploration Customization: Find the Ideal General Purpose Baseline Architecture
▸Why customization?!? ▸What is a proper general purpose baseline architecture? ▹Out-of-order (Silvermont, A15) or in-order (Saltwell, A7)? ▹Are existing general purpose mobile designs ideal? ▸Exhaustive design space exploration Customization: Find the Ideal General Purpose Baseline Architecture
Design Space Exploration (DSE) Setup ▸Integrated power (McPAT) and performance x86 full-system simulator (Marss86) ▸WebKit engine in the Chromium Web browser 10
Design Space Exploration (DSE) Setup ▸Integrated power (McPAT) and performance x86 full-system simulator (Marss86) ▸WebKit engine in the Chromium Web browser 10
▹PCs calculated from webpage-inherent and µarch-dependent features (~400 in total) Design Space Exploration (DSE) Setup 11 ▸Webpages selection using PCA
▹PCs calculated from webpage-inherent and µarch-dependent features (~400 in total) ▹PCs calculated from webpage-inherent and µarch-dependent features (~400 in total) Design Space Exploration (DSE) Setup 11 ▸Webpages selection using PCA 10-4 10-3 10-2 10-1 100 101 PC2 (log) -5 0 5 PC1 dominated by # webpage elements
▹PCs calculated from webpage-inherent and µarch-dependent features (~400 in total) ▹PCs calculated from webpage-inherent and µarch-dependent features (~400 in total) ▹PCs calculated from webpage-inherent and µarch-dependent features (~400 in total) Design Space Exploration (DSE) Setup 11 ▸Webpages selection using PCA 10-4 10-3 10-2 10-1 100 101 PC2 (log) -5 0 5 PC1 dominated by IPC
Design Space Exploration (DSE) Findings ▸Out-of-order µarchitecture is much more flexible 12 ▸In-order cores are acceptable if end-users can tolerate latency
Agenda of Today’s Talk ▸Motivation of our work: energy-efficiency of the mobile Web ▸How does WebCore improve the energy-efficiency? ▹Customization ▹Specialization -Mitigate instruction delivery: Style resolution unit (SRU) -Improving data feeding: Browser engine cache ▸Evaluation Results ▸Related Work 16
L1 D-cache WebCore Specialization Overview 17 Customized core IF ID MEM WB ALU MUL FPU SRU Style_apply(Id); Hardware Layer API Layer Browser Engine Cache
DOM_LD(Id, &attr); DOM_ST(Id, &attr); L1 D-cache WebCore Specialization Overview 17 Customized core IF ID MEM WB ALU MUL FPU SRU Style_apply(Id); Hardware Layer API Layer Browser Engine Cache
DOM_LD(Id, &attr); DOM_ST(Id, &attr); L1 D-cache WebCore Specialization Overview 17 Customized core IF ID MEM WB ALU MUL FPU SRU Style_apply(Id); Hardware Layer API Layer Runtime Layer Browser Engine Cache
Agenda of Today’s Talk ▸Motivation of our work: energy-efficiency of the mobile Web ▸How does WebCore improve the energy-efficiency? ▹Customization ▹Specialization -Mitigate instruction delivery: Style resolution unit (SRU) -Improving data feeding: Browser engine cache ▸Evaluation Results ▸Related Work 18
▸Style kernel is the most critical kernel Style Resolution Unit 19 for (each rule in matchedRules) { for (each property in rule) { switch (property.id) { case Font: Style[Font] = Handler(property.value, DOMNode); break; case N: ...}}}
▸Style kernel is the most critical kernel Style Resolution Unit 19 for (each rule in matchedRules) { for (each property in rule) { switch (property.id) { case Font: Style[Font] = Handler(property.value, DOMNode); break; case N: ...}}}
▸Style kernel is the most critical kernel Style Resolution Unit 19 for (each rule in matchedRules) { for (each property in rule) { switch (property.id) { case Font: Style[Font] = Handler(property.value, DOMNode); break; case N: ...}}} Rule-level Parallelism (RLP)
▸Style kernel is the most critical kernel Style Resolution Unit 19 for (each rule in matchedRules) { for (each property in rule) { switch (property.id) { case Font: Style[Font] = Handler(property.value, DOMNode); break; case N: ...}}} Rule-level Parallelism (RLP)
▸Style kernel is the most critical kernel Style Resolution Unit 19 for (each rule in matchedRules) { for (each property in rule) { switch (property.id) { case Font: Style[Font] = Handler(property.value, DOMNode); break; case N: ...}}} Rule-level Parallelism (RLP) Property-level Parallelism (PLP)
▸Style kernel is the most critical kernel Style Resolution Unit 19 for (each rule in matchedRules) { for (each property in rule) { switch (property.id) { case Font: Style[Font] = Handler(property.value, DOMNode); break; case N: ...}}} Rule-level Parallelism (RLP) Property-level Parallelism (PLP) ▸Exploiting the parallelism to increase the arithmetic intensity and reduce instruction footprint
Property 1 Property 1 Property 2 Property 2 Property 3 Property 3 id value id value id value Final Style Info ▸A running example from www.cnn.com Style Resolution Unit (2) Rule Property 1 Property 1 Property 2 Property 2 Rule id value id value 1 padding 0 margin 0 2 padding 6 px width 36 px Style Rules padding 0 width 6 px 36 px margin 0 High priority
Property 1 Property 1 Property 2 Property 2 Property 3 Property 3 id value id value id value Final Style Info ▸A running example from www.cnn.com Style Resolution Unit (2) Rule Property 1 Property 1 Property 2 Property 2 Rule id value id value 1 padding 0 margin 0 2 padding 6 px width 36 px Style Rules padding 0 width 6 px 36 px margin 0 High priority
Property 1 Property 1 Property 2 Property 2 Property 3 Property 3 id value id value id value Final Style Info ▸A running example from www.cnn.com Style Resolution Unit (2) Rule Property 1 Property 1 Property 2 Property 2 Rule id value id value 1 padding 0 margin 0 2 padding 6 px width 36 px Style Rules padding 0 width 6 px 36 px margin 0 High priority
Property 1 Property 1 Property 2 Property 2 Property 3 Property 3 id value id value id value Final Style Info ▸A running example from www.cnn.com Style Resolution Unit (2) Rule Property 1 Property 1 Property 2 Property 2 Rule id value id value 1 padding 0 margin 0 2 padding 6 px width 36 px Style Rules padding 0 width 6 px 36 px margin 0 High priority
Property 1 Property 1 Property 2 Property 2 Property 3 Property 3 id value id value id value Final Style Info ▸A running example from www.cnn.com Style Resolution Unit (2) Rule Property 1 Property 1 Property 2 Property 2 Rule id value id value 1 padding 0 margin 0 2 padding 6 px width 36 px Style Rules padding 0 width 6 px 36 px margin 0 High priority
Property 1 Property 1 Property 2 Property 2 Property 3 Property 3 id value id value id value Final Style Info ▸A running example from www.cnn.com Style Resolution Unit (2) Rule Property 1 Property 1 Property 2 Property 2 Rule id value id value 1 padding 0 margin 0 2 padding 6 px width 36 px Style Rules padding 0 width 6 px 36 px margin 0 High priority
Property 1 Property 1 Property 2 Property 2 Property 3 Property 3 id value id value id value Final Style Info ▸A running example from www.cnn.com Style Resolution Unit (2) Rule Property 1 Property 1 Property 2 Property 2 Rule id value id value 1 padding 0 margin 0 2 padding 6 px width 36 px Style Rules padding 0 width 6 px 36 px ▸Order Matters in RLP ▸Order Does Not Matter in PLP margin 0 High priority
Property 1 Property 1 Property 2 Property 2 Property 3 Property 3 id value id value id value Final Style Info ▸A running example from www.cnn.com Style Resolution Unit (2) Rule Property 1 Property 1 Property 2 Property 2 Rule id value id value 1 padding 0 margin 0 2 padding 6 px width 36 px Style Rules padding 0 width 6 px 36 px ▸Order Matters in RLP ▸Order Does Not Matter in PLP margin 0 High priority
Property 1 Property 1 Property 2 Property 2 Property 3 Property 3 id value id value id value Final Style Info ▸A running example from www.cnn.com Style Resolution Unit (2) Rule Property 1 Property 1 Property 2 Property 2 Rule id value id value 1 padding 0 margin 0 2 padding 6 px width 36 px Style Rules padding 0 width 6 px 36 px ▸Order Matters in RLP ▸Order Does Not Matter in PLP margin 0 High priority
... ... Rule j ... ... Prop l ... ... Rule i.id ... Prop m ... Prop k ... Rule j.id ... ... ... ... ... start end start end Rule i Prop k Prop m Prop m Prop l Style l Style m Style k Style Resolution Unit (3) 21 ▸Order Matters in RLP ▸Order Does Not Matter in PLP
... ... Rule j ... ... Prop l ... ... Rule i.id ... Prop m ... Prop k ... Rule j.id ... ... ... ... ... start end start end Rule i Prop k Prop m Prop m Prop l Style l Style m Style k Style Resolution Unit (3) 21 Input Scratchpad Memory ▸Order Matters in RLP ▸Order Does Not Matter in PLP
... ... Rule j ... ... Prop l ... ... Rule i.id ... Prop m ... Prop k ... Rule j.id ... ... ... ... ... start end start end Rule i Prop k Prop m Prop m Prop l Style l Style m Style k Style Resolution Unit (3) 21 Input Scratchpad Memory ▸Order Matters in RLP ▸Order Does Not Matter in PLP Higher Priority
... ... Rule j ... ... Prop l ... ... Rule i.id ... Prop m ... Prop k ... Rule j.id ... ... ... ... ... start end start end Rule i Prop k Prop m Prop m Prop l Style l Style m Style k Style Resolution Unit (3) 21 Input Scratchpad Memory Conflict Resolution ▸Order Matters in RLP ▸Order Does Not Matter in PLP Higher Priority
... ... Rule j ... ... Prop l ... ... Rule i.id ... Prop m ... Prop k ... Rule j.id ... ... ... ... ... start end start end Rule i Prop k Prop m Prop m Prop l Style l Style m Style k Style Resolution Unit (3) 21 Input Scratchpad Memory Conflict Resolution ▸Order Matters in RLP ▸Order Does Not Matter in PLP Higher Priority Prop m Prop m
... ... Rule j ... ... Prop l ... ... Rule i.id ... Prop m ... Prop k ... Rule j.id ... ... ... ... ... start end start end Rule i Prop k Prop m Prop m Prop l Style l Style m Style k Style Resolution Unit (3) 21 Input Scratchpad Memory Conflict Resolution ▸Order Matters in RLP ▸Order Does Not Matter in PLP Higher Priority Prop m
... ... Rule j ... ... Prop l ... ... Rule i.id ... Prop m ... Prop k ... Rule j.id ... ... ... ... ... start end start end Rule i Prop k Prop m Prop m Prop l Style l Style m Style k Style Resolution Unit (3) 21 Input Scratchpad Memory Conflict Resolution Compute Lanes ▸Order Matters in RLP ▸Order Does Not Matter in PLP Higher Priority
... ... Rule j ... ... Prop l ... ... Rule i.id ... Prop m ... Prop k ... Rule j.id ... ... ... ... ... start end start end Rule i Prop k Prop m Prop m Prop l Style l Style m Style k Style Resolution Unit (3) 21 Input Scratchpad Memory Output Scratchpad Memory Conflict Resolution Compute Lanes ▸Order Matters in RLP ▸Order Does Not Matter in PLP Higher Priority
Agenda of Today’s Talk ▸Motivation of our work: energy-efficiency of the mobile Web ▸How does WebCore improve the energy-efficiency? ▹Customization ▹Specialization ▸Evaluation Results ▸Related Work 22
Evaluations 25 0.55 0.688 0.825 0.963 1.1 1.6 1.8 2 2.2 2.4 Energy (J) Load Time (s) A15-like design Customization Specialization Cost of specialization: 0.59 mm2 area overhead Better than scaling- up approaches
Evaluations 25 0.55 0.688 0.825 0.963 1.1 1.6 1.8 2 2.2 2.4 Energy (J) Load Time (s) A15-like design Customization Specialization Cost of specialization: 0.59 mm2 area overhead Better than scaling- up approaches I$
Evaluations 25 0.55 0.688 0.825 0.963 1.1 1.6 1.8 2 2.2 2.4 Energy (J) Load Time (s) A15-like design Customization Specialization Cost of specialization: 0.59 mm2 area overhead Better than scaling- up approaches D$
Evaluations 25 0.55 0.688 0.825 0.963 1.1 1.6 1.8 2 2.2 2.4 Energy (J) Load Time (s) A15-like design Customization Specialization Cost of specialization: 0.59 mm2 area overhead Better than scaling- up approaches I+D$
Related Work 26 Hardware Software Focus on Performance Focus on Energy-Efficiency Parallelization Algorithm- level Zoomm Mozilla Servo System- level Optimizations Redundancy Removal Prefetching Big/little Scheduling
Conclusions 27 The Web browser has become a general purpose platform that supports a wide range of mobile Web applications Customization allows us to find the ideal general-purpose baseline architecture Hardware/software collaborative specialization leverages application knowledge to mitigate inefficiencies in general-purpose architectures
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