Re: [PATCH] x86/fred: Optimize the FRED entry by prioritizing high-probability event dispatching

[Xin Li]

On 1/16/2025 9:18 PM, Ethan Zhao wrote:
> > Just swap the 2 arguments, and it should be:
> > +    switch_likely (etype, EVENT_TYPE_OTHER) {
> after swapped the parameters as following:
> +#define switch_likely(v,l) \
> + switch((__typeof__(v))__builtin_expect((v),(l)))
> +
>   __visible noinstr void fred_entry_from_user(struct pt_regs *regs)
>   {
>          unsigned long error_code = regs->orig_ax;
> +       unsigned short etype = regs->fred_ss.type & 0xf;
>
>          /* Invalidate orig_ax so that syscall_get_nr() works correctly */
>          regs->orig_ax = -1;
>
> -       switch (regs->fred_ss.type) {
> +       switch_likely (etype, (EVENT_TYPE_EXTINT == etype || 
> EVENT_TYPE_OTHER == etype)) {

This is not what I suggested, the (l) argument should be only one
constant; __builtin_expect() doesn't allow 2 different constants.