On Fri, Mar 07, 2025 at 07:57:48AM +0100, Jiri Slaby wrote: > On 06. 03. 25, 17:25, Kuan-Wei Chiu wrote: > > Several parts of the kernel contain redundant implementations of parity > > calculations for 16/32/64-bit values. Introduces generic > > parity16/32/64() helpers in bitops.h, providing a standardized > > and optimized implementation. > > > > Subsequent patches refactor various kernel components to replace > > open-coded parity calculations with the new helpers, reducing code > > duplication and improving maintainability. > > > > Co-developed-by: Yu-Chun Lin <eleanor15x@xxxxxxxxx> > > Signed-off-by: Yu-Chun Lin <eleanor15x@xxxxxxxxx> > > Signed-off-by: Kuan-Wei Chiu <visitorckw@xxxxxxxxx> > > --- > > In v3, I use parityXX() instead of the parity() macro since the > > parity() macro may generate suboptimal code and requires special hacks > > to make GCC happy. If anyone still prefers a single parity() macro, > > please let me know. > > What is suboptimal and where exactly it matters? Have you actually measured > it? I asked exactly this question at least 3 times, and have never received perf tests or asm listings - nothing. I've never received any comments from driver maintainers about how performance of the parity() is important for them, as well. With the absence of _any_ feedback, I'm not going to take this series, of course, for the reason: overengineering. With that said, the simplest way would be replacing parity8(u8) with parity(u64) 'one size fits all' thing. I even made a one extra step, suggesting a macro that would generate a better code for smaller types with almost no extra maintenance burden. This is another acceptable option to me. Thanks, Yury
