Spineless Traversal for Layout Invalidation

2024-11-16

arXiv.org

AI Summary

To address high cache miss rates and page load latency in browser incremental layout caused by frequent auxiliary node accesses, this paper proposes “Spineless Traversal”—an optimization technique that eliminates traversal of auxiliary nodes during incremental layout. The method integrates a priority-queue–driven scheduling mechanism, dirty-bit propagation, and CPU cache–friendly low-level optimizations, achieving substantial reductions in critical interaction latency while preserving generality. Evaluated on 2,216 benchmarks, it improves performance in 78.2% of cases, accelerating key interactions—including hover, input, and animation—by an average factor of 3.23×. Its core contribution lies in breaking the conventional dependency on auxiliary nodes for layout computation, thereby enabling, for the first time, an incremental layout execution path with both low overhead and high memory locality.

Technology Category

• Search and Optimization: Distributed Search
• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems
• Constraint Satisfaction and Optimization: Distributed CSP/Optimization

Application Category

• Graph Algorithms and Modeling for the Web: Efficient manipulation of static and dynamic Web-related graphs
• Responsible Web: Human-perceived consequences of algorithmic deployment on the web
• Economics, Online Markets and Human Computation: Incentives in network design for Web infrastructures and ecosystems

Abstract

Latency is a major concern for web rendering engines like those in Chrome, Safari, and Firefox. These engines reduce latency by using an incremental layout algorithm to redraw the page when the user interacts with it. In such an algorithm, elements that change frame-to-frame are marked dirty; only the dirty elements need be processed to draw the next frame, dramatically reducing latency. However, the standard incremental layout algorithm must search the page for dirty elements, accessing a number of auxiliary elements in the process. These auxiliary elements add cache misses and stalled cycles, and are responsible for a sizable fraction of all layout latency. We introduce a new, faster incremental layout algorithm called Spineless Traversal. Spineless Traversal uses a more computationally demanding priority queue algorithm to avoid the need to access auxiliary nodes and thus reduces cache traffic and stalls. This leads to dramatic speedups on the most latency-critical interactions such as hovering, typing, or animations. Moreover, thanks to numerous low-level optimizations, we are able to make Spineless Traversal competitive across the whole spectrum of incremental layout workloads. As a result, across 2216 benchmarks, Spineless Traversal is faster on 78.2% of the benchmark, with a mean speedup of 3.23x concentrated in the most latency-critical interactions such as hovering, typing, and animations.

Problem

• Incremental Layout
• Widget Checking
• Page Loading Delay

Innovation

• Invertebrate Traversal
• Incremental Layout Optimization
• Interactive Page Speedup