[RFC][PATCH 0/5] preempt_count rework

Peter Zijlstra
2013-08-14T13:35:06Z

These patches optimize preempt_enable by firstly folding the preempt and
need_resched tests into one -- this should work for all architectures. And
secondly by providing per-arch preempt_count implementations; with x86 using
per-cpu preempt_count for fastest access.

These patches have so far only been compiled for defconfig-x86_64 +
CONFIG_PREEMPT=y and boot tested with kvm -smp 4 upto wanting to mount root.

It still needs asm volatile("call preempt_schedule": : :"memory"); as per
Andi's other patches to avoid the C calling convention cluttering the
preempt_enable() sites.

---
arch/alpha/include/asm/Kbuild | 1 +
arch/arc/include/asm/Kbuild | 1 +
arch/arm/include/asm/Kbuild | 1 +
arch/arm64/include/asm/Kbuild | 1 +
arch/avr32/include/asm/Kbuild | 1 +
arch/blackfin/include/asm/Kbuild | 1 +
arch/c6x/include/asm/Kbuild | 1 +
arch/cris/include/asm/Kbuild | 1 +
arch/frv/include/asm/Kbuild | 1 +
arch/h8300/include/asm/Kbuild | 1 +
arch/hexagon/include/asm/Kbuild | 1 +
arch/ia64/include/asm/Kbuild | 1 +
arch/m32r/include/asm/Kbuild | 1 +
arch/m68k/include/asm/Kbuild | 1 +
arch/metag/include/asm/Kbuild | 1 +
arch/microblaze/include/asm/Kbuild | 1 +
arch/mips/include/asm/Kbuild | 1 +
arch/mn10300/include/asm/Kbuild | 1 +
arch/openrisc/include/asm/Kbuild | 1 +
arch/parisc/include/asm/Kbuild | 1 +
arch/powerpc/include/asm/Kbuild | 1 +
arch/s390/include/asm/Kbuild | 1 +
arch/score/include/asm/Kbuild | 1 +
arch/sh/include/asm/Kbuild | 1 +
arch/sparc/include/asm/Kbuild | 1 +
arch/tile/include/asm/Kbuild | 1 +
arch/um/include/asm/Kbuild | 1 +
arch/unicore32/include/asm/Kbuild | 1 +
arch/x86/include/asm/thread_info.h | 5 ++---
arch/x86/kernel/asm-offsets.c | 1 -
arch/x86/kernel/cpu/common.c | 5 +++++
arch/x86/kernel/entry_32.S | 7 ++-----
arch/x86/kernel/entry_64.S | 4 +---
arch/x86/kernel/process_32.c | 10 ++++++++++
arch/x86/kernel/process_64.c | 10 ++++++++++
arch/xtensa/include/asm/Kbuild | 1 +
include/linux/preempt.h | 49 ++++++++++++++++++++++++++++++++++++++-----------
include/linux/sched.h | 2 +-
include/linux/thread_info.h | 1 +
include/trace/events/sched.h | 2 +-
init/main.c | 2 +-
kernel/context_tracking.c | 3 +--
kernel/cpu/idle.c | 10 ++++++++++
kernel/sched/core.c | 31 +++++++++++++++++++------------
kernel/softirq.c | 4 ++--
kernel/timer.c | 8 ++++----
lib/smp_processor_id.c | 3 +--
47 files changed, 138 insertions(+), 48 deletions(-)