| Message ID | 20230403052233.1880567-8-ankur.a.arora@oracle.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | x86/clear_huge_page: multi-page clearing | expand |
On Sun, Apr 02, 2023 at 10:22:31PM -0700, Ankur Arora wrote: > Define TIF_ALLOW_RESCHED to allow threads to mark themselves as allowing > rescheduling in the irqexit path with PREEMPTION_NONE/_VOLUNTARY. > > This is meant to be used for long running tasks where it is > not convenient to periodically call cond_resched(). > > Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> > Signed-off-by: Ankur Arora <ankur.a.arora@oracle.com> > --- > arch/x86/include/asm/thread_info.h | 2 ++ > include/linux/sched.h | 29 +++++++++++++++++++++++++++++ > 2 files changed, 31 insertions(+) > > diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h > index f1cccba52eb9..8c18b9eaeec4 100644 > --- a/arch/x86/include/asm/thread_info.h > +++ b/arch/x86/include/asm/thread_info.h > @@ -100,6 +100,7 @@ struct thread_info { > #define TIF_BLOCKSTEP 25 /* set when we want DEBUGCTLMSR_BTF */ > #define TIF_LAZY_MMU_UPDATES 27 /* task is updating the mmu lazily */ > #define TIF_ADDR32 29 /* 32-bit address space on 64 bits */ > +#define TIF_RESCHED_ALLOW 30 /* can reschedule if needed */ > > #define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME) > #define _TIF_SIGPENDING (1 << TIF_SIGPENDING) > @@ -122,6 +123,7 @@ struct thread_info { > #define _TIF_BLOCKSTEP (1 << TIF_BLOCKSTEP) > #define _TIF_LAZY_MMU_UPDATES (1 << TIF_LAZY_MMU_UPDATES) > #define _TIF_ADDR32 (1 << TIF_ADDR32) > +#define _TIF_RESCHED_ALLOW (1 << TIF_RESCHED_ALLOW) > > /* flags to check in __switch_to() */ > #define _TIF_WORK_CTXSW_BASE \ > diff --git a/include/linux/sched.h b/include/linux/sched.h > index 63d242164b1a..1e7536e6d9ce 100644 > --- a/include/linux/sched.h > +++ b/include/linux/sched.h > @@ -2229,6 +2229,35 @@ static __always_inline bool need_resched(void) > return unlikely(tif_need_resched()); > } > > +/* > + * Define this in common code to avoid include hell. > + */ > +static __always_inline bool resched_allowed(void) > +{ > +#ifndef TIF_RESCHED_ALLOW > + return false; > +#else > + return unlikely(test_tsk_thread_flag(current, TIF_RESCHED_ALLOW)); > +#endif > +} > + > +static inline void allow_resched(void) > +{ > + /* > + * allow_resched() allows preemption via the irqexit context. > + * To ensure that we stick around on the current runqueue, > + * disallow migration. > + */ > + migrate_disable(); > + set_tsk_thread_flag(current, TIF_RESCHED_ALLOW); > +} > + > +static inline void disallow_resched(void) > +{ > + clear_tsk_thread_flag(current, TIF_RESCHED_ALLOW); > + migrate_enable(); > +} Why the migrate_disable(), that comment doesn't help much.
diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h index f1cccba52eb9..8c18b9eaeec4 100644 --- a/arch/x86/include/asm/thread_info.h +++ b/arch/x86/include/asm/thread_info.h @@ -100,6 +100,7 @@ struct thread_info { #define TIF_BLOCKSTEP 25 /* set when we want DEBUGCTLMSR_BTF */ #define TIF_LAZY_MMU_UPDATES 27 /* task is updating the mmu lazily */ #define TIF_ADDR32 29 /* 32-bit address space on 64 bits */ +#define TIF_RESCHED_ALLOW 30 /* can reschedule if needed */ #define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME) #define _TIF_SIGPENDING (1 << TIF_SIGPENDING) @@ -122,6 +123,7 @@ struct thread_info { #define _TIF_BLOCKSTEP (1 << TIF_BLOCKSTEP) #define _TIF_LAZY_MMU_UPDATES (1 << TIF_LAZY_MMU_UPDATES) #define _TIF_ADDR32 (1 << TIF_ADDR32) +#define _TIF_RESCHED_ALLOW (1 << TIF_RESCHED_ALLOW) /* flags to check in __switch_to() */ #define _TIF_WORK_CTXSW_BASE \ diff --git a/include/linux/sched.h b/include/linux/sched.h index 63d242164b1a..1e7536e6d9ce 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -2229,6 +2229,35 @@ static __always_inline bool need_resched(void) return unlikely(tif_need_resched()); } +/* + * Define this in common code to avoid include hell. + */ +static __always_inline bool resched_allowed(void) +{ +#ifndef TIF_RESCHED_ALLOW + return false; +#else + return unlikely(test_tsk_thread_flag(current, TIF_RESCHED_ALLOW)); +#endif +} + +static inline void allow_resched(void) +{ + /* + * allow_resched() allows preemption via the irqexit context. + * To ensure that we stick around on the current runqueue, + * disallow migration. + */ + migrate_disable(); + set_tsk_thread_flag(current, TIF_RESCHED_ALLOW); +} + +static inline void disallow_resched(void) +{ + clear_tsk_thread_flag(current, TIF_RESCHED_ALLOW); + migrate_enable(); +} + /* * Wrappers for p->thread_info->cpu access. No-op on UP. */
Define TIF_ALLOW_RESCHED to allow threads to mark themselves as allowing rescheduling in the irqexit path with PREEMPTION_NONE/_VOLUNTARY. This is meant to be used for long running tasks where it is not convenient to periodically call cond_resched(). Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Ankur Arora <ankur.a.arora@oracle.com> --- arch/x86/include/asm/thread_info.h | 2 ++ include/linux/sched.h | 29 +++++++++++++++++++++++++++++ 2 files changed, 31 insertions(+)