On 2022/6/15 20:42, Matthew Wilcox wrote: > On Wed, Jun 15, 2022 at 03:44:06PM +0800, Miaohe Lin wrote: >>> We definitely don't need the unlikely here. >> >> Could you please give me a more detailed explanation? IIUC, the above if condition >> will only meet at a probability of 1/512. So unlikely tells the compiler to do some >> optimization around it. Or am I miss something? > > Only add unlikely() when the compiler can't figure out for itself that > it's unlikely. You should also check the generated code and/or > benchmark the results to be sure that it's actually an improvement. > Using unlikely() needs to be backed up with more than just a feeling. I see. Many thanks for clarifying. Will keep it in mind. :) > > . >
