This post explores optimizing Ruby's Foreign Function Interface (FFI) performance by using tiny Just-In-Time (JIT) compilers. The author demonstrates how generating specialized machine code for specific FFI calls can drastically reduce overhead compared to the generic FFI invocation process. They present a proof-of-concept implementation using Rust and inline assembly, showcasing significant speed improvements, especially for repeated calls with the same argument types. While acknowledging limitations and areas for future development, like handling different calling conventions and more complex types, the post concludes that tiny JITs offer a promising path toward a much faster Ruby FFI.
The blog post argues for a standardized, cross-platform OS API specifically designed for timers. Existing timer mechanisms, like POSIX's timerfd and Windows' CreateWaitableTimer, while useful, differ significantly across operating systems, complicating cross-platform development. The author proposes a new API with a consistent interface that abstracts away these platform-specific details. This ideal API would allow developers to create, arm, and disarm timers, specifying absolute or relative deadlines with optional periodic behavior, all while handling potential issues like early wake-ups gracefully. This would simplify codebases and improve portability for applications relying on precise timing across different operating systems.
The Hacker News comments discuss the complexities of cross-platform timer APIs, largely agreeing with the article's premise. Several commenters highlight the difficulties introduced by different operating systems' power management features, impacting timer accuracy and reliability. Specific challenges like signal coalescing and the lack of a unified interface for monotonic timers are mentioned. Some propose workarounds like busy-waiting for short durations or using platform-specific code for optimal performance. The need for a standardized API is reiterated, with suggestions for what such an API should offer, including considerations for power efficiency and different timer resolutions. One commenter points to the challenges of abstracting away hardware differences completely, suggesting the ideal solution may involve a combination of OS-level improvements and application-specific strategies.
Summary of Comments ( 109 )
https://news.ycombinator.com/item?id=43030388
The Hacker News comments on "Tiny JITs for a Faster FFI" express skepticism about the practicality of tiny JITs in real-world scenarios. Several commenters question the performance gains, citing the overhead of the JIT itself and the potential for optimization by the host language's runtime. They argue that a well-optimized native library, or even careful use of the host language's FFI, could often outperform a tiny JIT. One commenter notes the difficulties of debugging and maintaining such a system, and another raises security concerns related to executing untrusted code. The overall sentiment leans towards established optimization techniques rather than introducing a new layer of complexity with a tiny JIT.
The Hacker News post "Tiny JITs for a Faster FFI" has generated a moderate discussion with several interesting comments. Many of the comments revolve around the trade-offs and nuances of using Just-In-Time (JIT) compilation for Foreign Function Interfaces (FFIs).
One commenter points out the performance benefits observed when using a simple JIT for Lua's FFI, highlighting a significant speedup. They further discuss the inherent costs associated with traditional FFIs, such as argument marshaling and context switching, which a JIT can mitigate. The commenter's experience adds practical weight to the article's premise.
Another comment thread delves into the complexities of implementing a truly portable JIT given the variations in Application Binary Interfaces (ABIs) across different operating systems and architectures. This discussion highlights the challenge of creating a "tiny" and efficient JIT compiler that remains universally applicable. One participant suggests focusing on specific, commonly used platforms initially to simplify the development process.
A separate commenter mentions the potential security implications of JIT compilation, particularly in scenarios involving untrusted code. They emphasize the need for careful consideration of security risks when incorporating JIT techniques into an FFI, especially when dealing with external libraries or user-provided code. This comment serves as a valuable reminder of the security considerations associated with dynamic code generation.
Another comment discusses the existing use of small JITs in various projects like WebKit, suggesting that the concept presented in the article is not entirely novel. They link to a relevant talk about a register-based virtual machine with a JIT compiler used for JavaScriptCore, providing further context for those interested in existing implementations.
Some comments briefly touch upon alternative approaches to optimizing FFIs, such as using code generation during build time or employing specialized libraries. While these suggestions are not explored in detail, they offer additional perspectives on addressing FFI performance bottlenecks.
Finally, one comment questions the necessity of a JIT compiler in some cases, arguing that careful optimization of the FFI itself can often achieve comparable performance gains without the complexity of dynamic code generation. This counterpoint adds balance to the discussion and encourages consideration of alternative optimization strategies.
Overall, the comments on Hacker News provide valuable insights into the potential benefits, challenges, and trade-offs associated with using tiny JIT compilers for FFIs. They expand upon the article's core ideas by exploring practical experiences, security considerations, existing implementations, and alternative optimization techniques.