From: Andi Kleen Date: Mon, 26 Jun 2006 11:59:11 +0000 (+0200) Subject: [PATCH] i386/x86-64/ia64: Move polling flag into thread_info_status X-Git-Tag: v2.6.18-rc1~612^2~19 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=495ab9c045e1b0e5c82951b762257fe1c9d81564;p=linux-2.6 [PATCH] i386/x86-64/ia64: Move polling flag into thread_info_status During some profiling I noticed that default_idle causes a lot of memory traffic. I think that is caused by the atomic operations to clear/set the polling flag in thread_info. There is actually no reason to make this atomic - only the idle thread does it to itself, other CPUs only read it. So I moved it into ti->status. Converted i386/x86-64/ia64 for now because that was the easiest way to fix ACPI which also manipulates these flags in its idle function. Cc: Nick Piggin Cc: Tony Luck Cc: Len Brown Signed-off-by: Andi Kleen Signed-off-by: Linus Torvalds --- diff --git a/arch/i386/kernel/apm.c b/arch/i386/kernel/apm.c index 9e819eb682..7c5729d1fd 100644 --- a/arch/i386/kernel/apm.c +++ b/arch/i386/kernel/apm.c @@ -764,9 +764,9 @@ static int apm_do_idle(void) int idled = 0; int polling; - polling = test_thread_flag(TIF_POLLING_NRFLAG); + polling = !!(current_thread_info()->status & TS_POLLING); if (polling) { - clear_thread_flag(TIF_POLLING_NRFLAG); + current_thread_info()->status &= ~TS_POLLING; smp_mb__after_clear_bit(); } if (!need_resched()) { @@ -774,7 +774,7 @@ static int apm_do_idle(void) ret = apm_bios_call_simple(APM_FUNC_IDLE, 0, 0, &eax); } if (polling) - set_thread_flag(TIF_POLLING_NRFLAG); + current_thread_info()->status |= TS_POLLING; if (!idled) return 0; diff --git a/arch/i386/kernel/process.c b/arch/i386/kernel/process.c index 525432e3fe..6946b06e27 100644 --- a/arch/i386/kernel/process.c +++ b/arch/i386/kernel/process.c @@ -102,7 +102,7 @@ void default_idle(void) local_irq_enable(); if (!hlt_counter && boot_cpu_data.hlt_works_ok) { - clear_thread_flag(TIF_POLLING_NRFLAG); + current_thread_info()->status &= ~TS_POLLING; smp_mb__after_clear_bit(); while (!need_resched()) { local_irq_disable(); @@ -111,7 +111,7 @@ void default_idle(void) else local_irq_enable(); } - set_thread_flag(TIF_POLLING_NRFLAG); + current_thread_info()->status |= TS_POLLING; } else { while (!need_resched()) cpu_relax(); @@ -174,7 +174,7 @@ void cpu_idle(void) { int cpu = smp_processor_id(); - set_thread_flag(TIF_POLLING_NRFLAG); + current_thread_info()->status |= TS_POLLING; /* endless idle loop with no priority at all */ while (1) { diff --git a/arch/ia64/kernel/process.c b/arch/ia64/kernel/process.c index 355d57970b..b045c27913 100644 --- a/arch/ia64/kernel/process.c +++ b/arch/ia64/kernel/process.c @@ -272,9 +272,9 @@ cpu_idle (void) /* endless idle loop with no priority at all */ while (1) { if (can_do_pal_halt) - clear_thread_flag(TIF_POLLING_NRFLAG); + current_thread_info()->status &= ~TS_POLLING; else - set_thread_flag(TIF_POLLING_NRFLAG); + current_thread_info()->status |= TS_POLLING; if (!need_resched()) { void (*idle)(void); diff --git a/arch/x86_64/kernel/process.c b/arch/x86_64/kernel/process.c index d6fa41459c..b596837a15 100644 --- a/arch/x86_64/kernel/process.c +++ b/arch/x86_64/kernel/process.c @@ -110,7 +110,7 @@ static void default_idle(void) { local_irq_enable(); - clear_thread_flag(TIF_POLLING_NRFLAG); + current_thread_info()->status &= ~TS_POLLING; smp_mb__after_clear_bit(); while (!need_resched()) { local_irq_disable(); @@ -119,7 +119,7 @@ static void default_idle(void) else local_irq_enable(); } - set_thread_flag(TIF_POLLING_NRFLAG); + current_thread_info()->status |= TS_POLLING; } /* @@ -202,8 +202,7 @@ static inline void play_dead(void) */ void cpu_idle (void) { - set_thread_flag(TIF_POLLING_NRFLAG); - + current_thread_info()->status |= TS_POLLING; /* endless idle loop with no priority at all */ while (1) { while (!need_resched()) { diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c index 3b97a5eae9..74173ce6aa 100644 --- a/drivers/acpi/processor_idle.c +++ b/drivers/acpi/processor_idle.c @@ -206,11 +206,11 @@ acpi_processor_power_activate(struct acpi_processor *pr, static void acpi_safe_halt(void) { - clear_thread_flag(TIF_POLLING_NRFLAG); + current_thread_info()->status &= ~TS_POLLING; smp_mb__after_clear_bit(); if (!need_resched()) safe_halt(); - set_thread_flag(TIF_POLLING_NRFLAG); + current_thread_info()->status |= TS_POLLING; } static atomic_t c3_cpu_count; @@ -330,10 +330,10 @@ static void acpi_processor_idle(void) * Invoke the current Cx state to put the processor to sleep. */ if (cx->type == ACPI_STATE_C2 || cx->type == ACPI_STATE_C3) { - clear_thread_flag(TIF_POLLING_NRFLAG); + current_thread_info()->status &= ~TS_POLLING; smp_mb__after_clear_bit(); if (need_resched()) { - set_thread_flag(TIF_POLLING_NRFLAG); + current_thread_info()->status |= TS_POLLING; local_irq_enable(); return; } @@ -371,7 +371,7 @@ static void acpi_processor_idle(void) t2 = inl(acpi_fadt.xpm_tmr_blk.address); /* Re-enable interrupts */ local_irq_enable(); - set_thread_flag(TIF_POLLING_NRFLAG); + current_thread_info()->status |= TS_POLLING; /* Compute time (ticks) that we were actually asleep */ sleep_ticks = ticks_elapsed(t1, t2) - cx->latency_ticks - C2_OVERHEAD; @@ -411,7 +411,7 @@ static void acpi_processor_idle(void) /* Re-enable interrupts */ local_irq_enable(); - set_thread_flag(TIF_POLLING_NRFLAG); + current_thread_info()->status |= TS_POLLING; /* Compute time (ticks) that we were actually asleep */ sleep_ticks = ticks_elapsed(t1, t2) - cx->latency_ticks - C3_OVERHEAD; diff --git a/include/asm-i386/thread_info.h b/include/asm-i386/thread_info.h index 8420ed1249..fdbc7f422e 100644 --- a/include/asm-i386/thread_info.h +++ b/include/asm-i386/thread_info.h @@ -140,8 +140,7 @@ register unsigned long current_stack_pointer asm("esp") __attribute_used__; #define TIF_SYSCALL_AUDIT 7 /* syscall auditing active */ #define TIF_SECCOMP 8 /* secure computing */ #define TIF_RESTORE_SIGMASK 9 /* restore signal mask in do_signal() */ -#define TIF_POLLING_NRFLAG 16 /* true if poll_idle() is polling TIF_NEED_RESCHED */ -#define TIF_MEMDIE 17 +#define TIF_MEMDIE 16 #define _TIF_SYSCALL_TRACE (1<thread_info->status & TS_POLLING) #endif /* __KERNEL__ */ diff --git a/include/asm-ia64/thread_info.h b/include/asm-ia64/thread_info.h index e5392c4d30..8bc9869e57 100644 --- a/include/asm-ia64/thread_info.h +++ b/include/asm-ia64/thread_info.h @@ -27,6 +27,7 @@ struct thread_info { __u32 flags; /* thread_info flags (see TIF_*) */ __u32 cpu; /* current CPU */ __u32 last_cpu; /* Last CPU thread ran on */ + __u32 status; /* Thread synchronous flags */ mm_segment_t addr_limit; /* user-level address space limit */ int preempt_count; /* 0=premptable, <0=BUG; will also serve as bh-counter */ struct restart_block restart_block; @@ -103,4 +104,8 @@ struct thread_info { /* like TIF_ALLWORK_BITS but sans TIF_SYSCALL_TRACE or TIF_SYSCALL_AUDIT */ #define TIF_WORK_MASK (TIF_ALLWORK_MASK&~(_TIF_SYSCALL_TRACE|_TIF_SYSCALL_AUDIT)) +#define TS_POLLING 1 /* true if in idle loop and not sleeping */ + +#define tsk_is_polling(t) ((t)->thread_info->status & TS_POLLING) + #endif /* _ASM_IA64_THREAD_INFO_H */ diff --git a/include/asm-x86_64/thread_info.h b/include/asm-x86_64/thread_info.h index 4ac0e0a369..b5e88216fd 100644 --- a/include/asm-x86_64/thread_info.h +++ b/include/asm-x86_64/thread_info.h @@ -101,7 +101,7 @@ static inline struct thread_info *stack_thread_info(void) #define TIF_IRET 5 /* force IRET */ #define TIF_SYSCALL_AUDIT 7 /* syscall auditing active */ #define TIF_SECCOMP 8 /* secure computing */ -#define TIF_POLLING_NRFLAG 16 /* true if poll_idle() is polling TIF_NEED_RESCHED */ +/* 16 free */ #define TIF_IA32 17 /* 32bit process */ #define TIF_FORK 18 /* ret_from_fork */ #define TIF_ABI_PENDING 19 @@ -115,7 +115,6 @@ static inline struct thread_info *stack_thread_info(void) #define _TIF_IRET (1<thread_info->status & TS_POLLING) #endif /* __KERNEL__ */ diff --git a/kernel/sched.c b/kernel/sched.c index f06d059ede..7d1027a4dd 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -818,6 +818,11 @@ static void deactivate_task(struct task_struct *p, runqueue_t *rq) * the target CPU. */ #ifdef CONFIG_SMP + +#ifndef tsk_is_polling +#define tsk_is_polling(t) test_tsk_thread_flag(t, TIF_POLLING_NRFLAG) +#endif + static void resched_task(task_t *p) { int cpu; @@ -833,9 +838,9 @@ static void resched_task(task_t *p) if (cpu == smp_processor_id()) return; - /* NEED_RESCHED must be visible before we test POLLING_NRFLAG */ + /* NEED_RESCHED must be visible before we test polling */ smp_mb(); - if (!test_tsk_thread_flag(p, TIF_POLLING_NRFLAG)) + if (!tsk_is_polling(p)) smp_send_reschedule(cpu); } #else