Hello,
On Thu, Dec 06, 2007 at 05:51:21PM +0100, Petr Tesarik wrote:
> The RSE synchronization will need a TIF_ flag, but all work-to-be-done
> bits are already used, so we'll have to multiplex TIF_NOTIFY_RESUME
> again.
>
Yes, I knew this was coming. I think it is okay to multiplex on
TIF_NOITFY_RESUME. However, I think it would be cleaner and likely
more efficient to add yet another TIF flags for perfmon instead of
adding the pfm_needs_checking field. That new TIF flag would not have
to be in the low 7 bits. It could be higher because it would not be
checked by the assembly code but rather in do_notify_resume_user().
The TIF limitation is just in the assembly code.
Any comments?
> Signed-off-by: Shaohua Li <shaohua.li@xxxxxxxxx>
> Signed-off-by: Petr Tesarik <ptesarik@xxxxxxx>
> ---
> arch/ia64/kernel/perfmon.c | 21 +++------------------
> arch/ia64/kernel/process.c | 9 +++++++++
> include/asm-ia64/thread_info.h | 9 ++++++---
> 3 files changed, 18 insertions(+), 21 deletions(-)
>
> diff --git a/arch/ia64/kernel/perfmon.c b/arch/ia64/kernel/perfmon.c
> index 73e7c2e..446e452 100644
> --- a/arch/ia64/kernel/perfmon.c
> +++ b/arch/ia64/kernel/perfmon.c
> @@ -586,21 +586,6 @@ pfm_put_task(struct task_struct *task)
> }
>
> static inline void
> -pfm_set_task_notify(struct task_struct *task)
> -{
> - struct thread_info *info;
> -
> - info = (struct thread_info *) ((char *) task + IA64_TASK_SIZE);
> - set_bit(TIF_PERFMON_WORK, &info->flags);
> -}
> -
> -static inline void
> -pfm_clear_task_notify(void)
> -{
> - clear_thread_flag(TIF_PERFMON_WORK);
> -}
> -
> -static inline void
> pfm_reserve_page(unsigned long a)
> {
> SetPageReserved(vmalloc_to_page((void *)a));
> @@ -3724,7 +3709,7 @@ pfm_restart(pfm_context_t *ctx, void *ar
>
> PFM_SET_WORK_PENDING(task, 1);
>
> - pfm_set_task_notify(task);
> + tsk_set_notify_resume(task);
>
> /*
> * XXX: send reschedule if task runs on another CPU
> @@ -5082,7 +5067,7 @@ pfm_handle_work(void)
>
> PFM_SET_WORK_PENDING(current, 0);
>
> - pfm_clear_task_notify();
> + tsk_clear_notify_resume(current);
>
> regs = task_pt_regs(current);
>
> @@ -5450,7 +5435,7 @@ pfm_overflow_handler(struct task_struct
> * when coming from ctxsw, current still points to the
> * previous task, therefore we must work with task and not current.
> */
> - pfm_set_task_notify(task);
> + tsk_set_notify_resume(task);
> }
> /*
> * defer until state is changed (shorten spin window). the context is locked
> diff --git a/arch/ia64/kernel/process.c b/arch/ia64/kernel/process.c
> index 2418289..94a92de 100644
> --- a/arch/ia64/kernel/process.c
> +++ b/arch/ia64/kernel/process.c
> @@ -155,6 +155,15 @@ show_regs (struct pt_regs *regs)
> show_stack(NULL, NULL);
> }
>
> +void tsk_clear_notify_resume(struct task_struct *tsk)
> +{
> +#ifdef CONFIG_PERFMON
> + if (tsk->thread.pfm_needs_checking)
> + return;
> +#endif
> + clear_ti_thread_flag(task_thread_info(tsk), TIF_NOTIFY_RESUME);
> +}
> +
> void
> do_notify_resume_user (sigset_t *unused, struct sigscratch *scr, long in_syscall)
> {
> diff --git a/include/asm-ia64/thread_info.h b/include/asm-ia64/thread_info.h
> index d16031e..5a2c479 100644
> --- a/include/asm-ia64/thread_info.h
> +++ b/include/asm-ia64/thread_info.h
> @@ -71,6 +71,9 @@ #define __HAVE_ARCH_TASK_STRUCT_ALLOCATO
> #define alloc_task_struct() ((struct task_struct *)__get_free_pages(GFP_KERNEL | __GFP_COMP, KERNEL_STACK_SIZE_ORDER))
> #define free_task_struct(tsk) free_pages((unsigned long) (tsk), KERNEL_STACK_SIZE_ORDER)
>
> +#define tsk_set_notify_resume(tsk) \
> + set_ti_thread_flag(task_thread_info(tsk), TIF_NOTIFY_RESUME)
> +extern void tsk_clear_notify_resume(struct task_struct *tsk);
> #endif /* !__ASSEMBLY */
>
> /*
> @@ -85,7 +88,7 @@ #define TIF_SYSCALL_TRACE 2 /* syscall t
> #define TIF_SYSCALL_AUDIT 3 /* syscall auditing active */
> #define TIF_SINGLESTEP 4 /* restore singlestep on return to user mode */
> #define TIF_RESTORE_SIGMASK 5 /* restore signal mask in do_signal() */
> -#define TIF_PERFMON_WORK 6 /* work for pfm_handle_work() */
> +#define TIF_NOTIFY_RESUME 6 /* resumption notification requested */
> #define TIF_POLLING_NRFLAG 16 /* true if poll_idle() is polling TIF_NEED_RESCHED */
> #define TIF_MEMDIE 17
> #define TIF_MCA_INIT 18 /* this task is processing MCA or INIT */
> @@ -97,7 +100,7 @@ #define _TIF_SYSCALL_AUDIT (1 << TIF_SYS
> #define _TIF_SINGLESTEP (1 << TIF_SINGLESTEP)
> #define _TIF_SYSCALL_TRACEAUDIT (_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT|_TIF_SINGLESTEP)
> #define _TIF_RESTORE_SIGMASK (1 << TIF_RESTORE_SIGMASK)
> -#define _TIF_PERFMON_WORK (1 << TIF_PERFMON_WORK)
> +#define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME)
> #define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
> #define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED)
> #define _TIF_POLLING_NRFLAG (1 << TIF_POLLING_NRFLAG)
> @@ -106,7 +109,7 @@ #define _TIF_DB_DISABLED (1 << TIF_DB_DI
> #define _TIF_FREEZE (1 << TIF_FREEZE)
>
> /* "work to do on user-return" bits */
> -#define TIF_ALLWORK_MASK (_TIF_SIGPENDING|_TIF_PERFMON_WORK|_TIF_SYSCALL_AUDIT|\
> +#define TIF_ALLWORK_MASK (_TIF_SIGPENDING|_TIF_NOTIFY_RESUME|_TIF_SYSCALL_AUDIT|\
> _TIF_NEED_RESCHED| _TIF_SYSCALL_TRACE|\
> _TIF_RESTORE_SIGMASK)
> /* like TIF_ALLWORK_BITS but sans TIF_SYSCALL_TRACE or TIF_SYSCALL_AUDIT */
>
> -
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--
-Stephane
-
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