[patch 0/3] x86/process: Optimize __switch_to_extra()

From: Thomas Gleixner
Date: Thu Dec 15 2016 - 11:47:27 EST


GCC generates lousy code in __switch_to_extra(). Aside of that some of the
operations there are implemented suboptimal.

This series, inspired by a patch from Kyle, helps the compiler to be less
stupid by explicitely giving the hints to optimize and replaces the open
coded bit toggle mechanisms with proper helper functions.

The resulting change in text size:

64bit 32bit
Before: 3726 9388
After: 3646 9324
Delta: 80 152

The number of conditional jumps is also reduced:

64bit 32bit
Before: 8 13
After: 5 10

Thanks,

tglx

---
include/asm/processor.h | 12 ++++++++
include/asm/tlbflush.h | 10 ++++++
kernel/process.c | 70 +++++++++++++++++++-----------------------------
3 files changed, 51 insertions(+), 41 deletions(-)