pitrou commented on PR #35565: URL: https://github.com/apache/arrow/pull/35565#issuecomment-1551579583
Overall I'm rather lukewarm about the whole alignment concerns. "Alignment requirements" are generally extremely vague about _why_ the requirements actually exist. Sometimes it's about not crashing on niche CPUs (such as SPARC), sometimes it's about not crashing on little-used SIMD instructions ([x86 aligned loads](https://stackoverflow.com/questions/52147378/choice-between-aligned-vs-unaligned-x86-simd-instructions)), sometimes it's about avoiding undefined behaviour (which is mostly a language compliance concern, as far as alignment is concerned), sometimes it's about getting better performance (by avoiding memory accesses straddling cache lines or - worse - page boundaries). So ideally I think we should remove the entire code that reallocates buffers to fix their alignment, but short from that we should strive to be as conservative and granular as possible (see the suggestion I posted above). -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
