On Thu, 2017-06-22 at 10:30 -0700, Linus Torvalds wrote: > So if you want to do this optimization, I'd argue that you should just > do it inside the copy_user_enhanced_fast_string() function itself, the > same way we already handle the really small case specially in > copy_user_generic_string(). > > And do *not* use the unrolled code, which isn't used for small copies > anyway - rewrite the "copy_user_generic_unrolled" function in that > same asm file to have the non-unrolled cases (label "17" and forward) > accessible, so that you don't bother re-testing the size.
Thank you for the feedback. I'm quite new to the core x86 land; the rep stosb cost popped out while messing with the networking. I'll try to dig into the asm. Regards, Paolo