diff options
author | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2016-10-25 12:21:44 +0200 |
---|---|---|
committer | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2016-11-11 16:37:40 +0100 |
commit | c360192bf4a8dc72f102dd6a4e1bf8bd0b404cfa (patch) | |
tree | c54104bae43978dfe31e6fc2c9a4d996218379fd /arch/s390/include/asm/preempt.h | |
parent | s390/bitops: use atomic primitives for bitops (diff) | |
download | linux-c360192bf4a8dc72f102dd6a4e1bf8bd0b404cfa.tar.xz linux-c360192bf4a8dc72f102dd6a4e1bf8bd0b404cfa.zip |
s390/preempt: move preempt_count to the lowcore
Convert s390 to use a field in the struct lowcore for the CPU
preemption count. It is a bit cheaper to access a lowcore field
compared to a thread_info variable and it removes the depencency
on a task related structure.
bloat-o-meter on the vmlinux image for the default configuration
(CONFIG_PREEMPT_NONE=y) reports a small reduction in text size:
add/remove: 0/0 grow/shrink: 18/578 up/down: 228/-5448 (-5220)
A larger improvement is achieved with the default configuration
but with CONFIG_PREEMPT=y and CONFIG_DEBUG_PREEMPT=n:
add/remove: 2/6 grow/shrink: 59/4477 up/down: 1618/-228762 (-227144)
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/include/asm/preempt.h')
-rw-r--r-- | arch/s390/include/asm/preempt.h | 137 |
1 files changed, 137 insertions, 0 deletions
diff --git a/arch/s390/include/asm/preempt.h b/arch/s390/include/asm/preempt.h new file mode 100644 index 000000000000..b0776b2c8dcf --- /dev/null +++ b/arch/s390/include/asm/preempt.h @@ -0,0 +1,137 @@ +#ifndef __ASM_PREEMPT_H +#define __ASM_PREEMPT_H + +#include <asm/current.h> +#include <linux/thread_info.h> +#include <asm/atomic_ops.h> + +#ifdef CONFIG_HAVE_MARCH_Z196_FEATURES + +#define PREEMPT_ENABLED (0 + PREEMPT_NEED_RESCHED) + +static inline int preempt_count(void) +{ + return READ_ONCE(S390_lowcore.preempt_count) & ~PREEMPT_NEED_RESCHED; +} + +static inline void preempt_count_set(int pc) +{ + int old, new; + + do { + old = READ_ONCE(S390_lowcore.preempt_count); + new = (old & PREEMPT_NEED_RESCHED) | + (pc & ~PREEMPT_NEED_RESCHED); + } while (__atomic_cmpxchg(&S390_lowcore.preempt_count, + old, new) != old); +} + +#define init_task_preempt_count(p) do { } while (0) + +#define init_idle_preempt_count(p, cpu) do { \ + S390_lowcore.preempt_count = PREEMPT_ENABLED; \ +} while (0) + +static inline void set_preempt_need_resched(void) +{ + __atomic_and(~PREEMPT_NEED_RESCHED, &S390_lowcore.preempt_count); +} + +static inline void clear_preempt_need_resched(void) +{ + __atomic_or(PREEMPT_NEED_RESCHED, &S390_lowcore.preempt_count); +} + +static inline bool test_preempt_need_resched(void) +{ + return !(READ_ONCE(S390_lowcore.preempt_count) & PREEMPT_NEED_RESCHED); +} + +static inline void __preempt_count_add(int val) +{ + if (__builtin_constant_p(val) && (val >= -128) && (val <= 127)) + __atomic_add_const(val, &S390_lowcore.preempt_count); + else + __atomic_add(val, &S390_lowcore.preempt_count); +} + +static inline void __preempt_count_sub(int val) +{ + __preempt_count_add(-val); +} + +static inline bool __preempt_count_dec_and_test(void) +{ + return __atomic_add(-1, &S390_lowcore.preempt_count) == 1; +} + +static inline bool should_resched(int preempt_offset) +{ + return unlikely(READ_ONCE(S390_lowcore.preempt_count) == + preempt_offset); +} + +#else /* CONFIG_HAVE_MARCH_Z196_FEATURES */ + +#define PREEMPT_ENABLED (0) + +static inline int preempt_count(void) +{ + return READ_ONCE(S390_lowcore.preempt_count); +} + +static inline void preempt_count_set(int pc) +{ + S390_lowcore.preempt_count = pc; +} + +#define init_task_preempt_count(p) do { } while (0) + +#define init_idle_preempt_count(p, cpu) do { \ + S390_lowcore.preempt_count = PREEMPT_ENABLED; \ +} while (0) + +static inline void set_preempt_need_resched(void) +{ +} + +static inline void clear_preempt_need_resched(void) +{ +} + +static inline bool test_preempt_need_resched(void) +{ + return false; +} + +static inline void __preempt_count_add(int val) +{ + S390_lowcore.preempt_count += val; +} + +static inline void __preempt_count_sub(int val) +{ + S390_lowcore.preempt_count -= val; +} + +static inline bool __preempt_count_dec_and_test(void) +{ + return !--S390_lowcore.preempt_count && tif_need_resched(); +} + +static inline bool should_resched(int preempt_offset) +{ + return unlikely(preempt_count() == preempt_offset && + tif_need_resched()); +} + +#endif /* CONFIG_HAVE_MARCH_Z196_FEATURES */ + +#ifdef CONFIG_PREEMPT +extern asmlinkage void preempt_schedule(void); +#define __preempt_schedule() preempt_schedule() +extern asmlinkage void preempt_schedule_notrace(void); +#define __preempt_schedule_notrace() preempt_schedule_notrace() +#endif /* CONFIG_PREEMPT */ + +#endif /* __ASM_PREEMPT_H */ |