Re: [PATCH] x86/uaccess: use unrolled string copy for short strings

[Alan Cox]

> > diff --git a/arch/x86/include/asm/uaccess_64.h b/arch/x86/include/asm/uaccess_64.h
> > index c5504b9..16a8871 100644
> > --- a/arch/x86/include/asm/uaccess_64.h
> > +++ b/arch/x86/include/asm/uaccess_64.h
> > @@ -28,6 +28,9 @@ copy_user_generic(void *to, const void *from, unsigned len)
> >  {
> >         unsigned ret;
> >
> > +       if (len <= 64)
> > +               return copy_user_generic_unrolled(to, from, len);
> > +

Given this gets inlined surely that should bracketed with an ifdef
against optimizing for space.

Also you give one set of benchmarks but how do they look on different
processors - AMD v Intel, Atom v Core, Ryzen v older AMD etc ?

Alan