Re: [rfc patch] i386: don't save eflags on task switch

Andi Kleen
2006-11-05T05:41:36Z

> For me, when compiled with -O2, it results in
>
> 84
> 88
> 132
>
> which basically says: a "rdtsc->rdtsc" is 84 cycles, putting a "pushfl" in
> between is another _4_ cycles, and putting a "popfl" in between is about
> another 48 cycles.

This means we should definitely change restore_flags() to only STI,
never popf

-Andi