Dynamically accelerating client-side web applications through decoupled execution

Abstract

Abstract-The emergence and wide adoption of web applications have moved the client-side component, often written in JavaScript, to the forefront of computing on the web. Web application developers try to move more computation to the client side to avoid unnecessary network traffic and make the applications more responsive. Therefore, JavaScript applications are becoming larger and more computation intensive. Trace-based just-in-time compilation have been proposed to address the performance bottleneck in these applications. In this paper, we exploit the extra processing power in multicore systems to further improve the performance of trace-based execution of JavaScript programs. In trace-based engines, a considerable portion of execution time is spent on running guards which are operations inserted in the native code to check if the properties assumed by the compiled code actually hold during execution. We introduce ParaGuard to off-load these guards to another thread, while speculatively executing the main trace. In a manner similar to what happens in current trace-based JITs, if a check fails, ParaGuard aborts the native trace execution and reverts back to interpreting the JavaScript bytecode. We also propose several optimizations including guard branch aggregation and profile-based snapshot elimination to further improve the performance of our technique. We show that ParaGuard can achieve an average of 15% performance improvement over current trace-based compilers using an extra processor on commodity multicore processors.

Enhancing the performance of assisted execution runtime systems through hardware/software techniques

“…Runtime systems benefit from the assisted execution model if application threads often require support to perform time-consuming operations [22,31]. Under these hypothesis, devoting hardware threads to perform runtime operations rather than main computation may provide higher performance than using all available hardware resources to run application threads.…”

“…Moreover, even for systems with limited runtime overhead, the theoretical speedup computed with the Amdahl's Law may not justify the use of all available cores/hardware threads. Both programming model runtime overhead and the Amdahl's Law limit on the theoretical speedup suggest the use of assisted execution models [11], in which some of the computing elements (cores or hardware threads) are used to support computation rather than being devoted to running additional application threads [22,31]. The intuition behind assisted execution models is that some of the computing elements can accelerate sequential part of the application and/or relieve application threads from handling runtime functionalities, therefore pushing further the theoretical Amdahl's Law's speedup.…”

Improving JavaScript performance by deconstructing the type system

“…Another proposal extends the ISA to load and check the type with a single instruction [9]. Finally, ParaGuard [19] and ParaScript [18] propose hardware support for parallel execution of JavaScript programs. The former offloads the runtime checks to another thread while the main thread continues with the execution of the user code; the latter uses speculative parallelization to support loop-level parallelization of JavaScript programs.…”

Reducing Memory in Software-Based Thread-Level Speculation for JavaScript Virtual Machine Execution of Web Applications

“…Thread-Level Speculation in JavaScript and for web applications Mehrara and Mahlke [12] target trace-based JIT-compiled JavaScript code, where the most common execution flow is compiled into an execution trace. Run-time checks (guards) are inserted to check whether control flow etc.…”