Feb. 19, 2013
9:41 p.m.
On Wed, 20 Feb 2013 01:58:17 +0700, Mulyadi Santosa said:
On Tue, Feb 19, 2013 at 7:20 PM, David Shwatrz <dshwatrz@gmail.com> wrote:
Hi, kernel newbies,
We have: #define cpu_relax() asm volatile("rep; nop") in arch/x86/boot/boot.h.
Why don't we use the PAUSE assembler instruction here ?
Just guessing, maybe rep+nop could do better power saving because processor is considered as idle.
The 'rep; nop' is actually a placeholder - for some CPUs, a different opcode gets filled in during boot time. See arch/x86/kernel/alternative.c and arch/x86/include/asm/alternative.h for the gory details.