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author | Linus Torvalds <torvalds@linux-foundation.org> | 2013-11-12 10:20:12 +0900 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-11-12 10:20:12 +0900 |
commit | 39cf275a1a18ba3c7eb9b986c5c9b35b57332798 (patch) | |
tree | 40b119ca9d2fbaf8128d3fa25f4c64669002b0c0 /arch/x86/include/asm/preempt.h | |
parent | ad5d69899e52792671c1aa6c7360464c7edfe09c (diff) | |
parent | e5137b50a0640009fd63a3e65c14bc6e1be8796a (diff) | |
download | linux-stable-39cf275a1a18ba3c7eb9b986c5c9b35b57332798.tar.gz linux-stable-39cf275a1a18ba3c7eb9b986c5c9b35b57332798.tar.bz2 linux-stable-39cf275a1a18ba3c7eb9b986c5c9b35b57332798.zip |
Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler changes from Ingo Molnar:
"The main changes in this cycle are:
- (much) improved CONFIG_NUMA_BALANCING support from Mel Gorman, Rik
van Riel, Peter Zijlstra et al. Yay!
- optimize preemption counter handling: merge the NEED_RESCHED flag
into the preempt_count variable, by Peter Zijlstra.
- wait.h fixes and code reorganization from Peter Zijlstra
- cfs_bandwidth fixes from Ben Segall
- SMP load-balancer cleanups from Peter Zijstra
- idle balancer improvements from Jason Low
- other fixes and cleanups"
* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (129 commits)
ftrace, sched: Add TRACE_FLAG_PREEMPT_RESCHED
stop_machine: Fix race between stop_two_cpus() and stop_cpus()
sched: Remove unnecessary iteration over sched domains to update nr_busy_cpus
sched: Fix asymmetric scheduling for POWER7
sched: Move completion code from core.c to completion.c
sched: Move wait code from core.c to wait.c
sched: Move wait.c into kernel/sched/
sched/wait: Fix __wait_event_interruptible_lock_irq_timeout()
sched: Avoid throttle_cfs_rq() racing with period_timer stopping
sched: Guarantee new group-entities always have weight
sched: Fix hrtimer_cancel()/rq->lock deadlock
sched: Fix cfs_bandwidth misuse of hrtimer_expires_remaining
sched: Fix race on toggling cfs_bandwidth_used
sched: Remove extra put_online_cpus() inside sched_setaffinity()
sched/rt: Fix task_tick_rt() comment
sched/wait: Fix build breakage
sched/wait: Introduce prepare_to_wait_event()
sched/wait: Add ___wait_cond_timeout() to wait_event*_timeout() too
sched: Remove get_online_cpus() usage
sched: Fix race in migrate_swap_stop()
...
Diffstat (limited to 'arch/x86/include/asm/preempt.h')
-rw-r--r-- | arch/x86/include/asm/preempt.h | 100 |
1 files changed, 100 insertions, 0 deletions
diff --git a/arch/x86/include/asm/preempt.h b/arch/x86/include/asm/preempt.h new file mode 100644 index 000000000000..8729723636fd --- /dev/null +++ b/arch/x86/include/asm/preempt.h @@ -0,0 +1,100 @@ +#ifndef __ASM_PREEMPT_H +#define __ASM_PREEMPT_H + +#include <asm/rmwcc.h> +#include <asm/percpu.h> +#include <linux/thread_info.h> + +DECLARE_PER_CPU(int, __preempt_count); + +/* + * We mask the PREEMPT_NEED_RESCHED bit so as not to confuse all current users + * that think a non-zero value indicates we cannot preempt. + */ +static __always_inline int preempt_count(void) +{ + return __this_cpu_read_4(__preempt_count) & ~PREEMPT_NEED_RESCHED; +} + +static __always_inline void preempt_count_set(int pc) +{ + __this_cpu_write_4(__preempt_count, pc); +} + +/* + * must be macros to avoid header recursion hell + */ +#define task_preempt_count(p) \ + (task_thread_info(p)->saved_preempt_count & ~PREEMPT_NEED_RESCHED) + +#define init_task_preempt_count(p) do { \ + task_thread_info(p)->saved_preempt_count = PREEMPT_DISABLED; \ +} while (0) + +#define init_idle_preempt_count(p, cpu) do { \ + task_thread_info(p)->saved_preempt_count = PREEMPT_ENABLED; \ + per_cpu(__preempt_count, (cpu)) = PREEMPT_ENABLED; \ +} while (0) + +/* + * We fold the NEED_RESCHED bit into the preempt count such that + * preempt_enable() can decrement and test for needing to reschedule with a + * single instruction. + * + * We invert the actual bit, so that when the decrement hits 0 we know we both + * need to resched (the bit is cleared) and can resched (no preempt count). + */ + +static __always_inline void set_preempt_need_resched(void) +{ + __this_cpu_and_4(__preempt_count, ~PREEMPT_NEED_RESCHED); +} + +static __always_inline void clear_preempt_need_resched(void) +{ + __this_cpu_or_4(__preempt_count, PREEMPT_NEED_RESCHED); +} + +static __always_inline bool test_preempt_need_resched(void) +{ + return !(__this_cpu_read_4(__preempt_count) & PREEMPT_NEED_RESCHED); +} + +/* + * The various preempt_count add/sub methods + */ + +static __always_inline void __preempt_count_add(int val) +{ + __this_cpu_add_4(__preempt_count, val); +} + +static __always_inline void __preempt_count_sub(int val) +{ + __this_cpu_add_4(__preempt_count, -val); +} + +static __always_inline bool __preempt_count_dec_and_test(void) +{ + GEN_UNARY_RMWcc("decl", __preempt_count, __percpu_arg(0), "e"); +} + +/* + * Returns true when we need to resched and can (barring IRQ state). + */ +static __always_inline bool should_resched(void) +{ + return unlikely(!__this_cpu_read_4(__preempt_count)); +} + +#ifdef CONFIG_PREEMPT + extern asmlinkage void ___preempt_schedule(void); +# define __preempt_schedule() asm ("call ___preempt_schedule") + extern asmlinkage void preempt_schedule(void); +# ifdef CONFIG_CONTEXT_TRACKING + extern asmlinkage void ___preempt_schedule_context(void); +# define __preempt_schedule_context() asm ("call ___preempt_schedule_context") +# endif +#endif + +#endif /* __ASM_PREEMPT_H */ |