[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 <npiggin@novell.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Len Brown <len.brown@intel.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

9 files changed, 37 insertions, 25 deletions

diff --git a/arch/i386/kernel/apm.c b/arch/i386/kernel/apm.c
index 9e819eb68229..7c5729d1fd06 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 525432e3fef7..6946b06e2784 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 355d57970ba3..b045c279136c 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 d6fa41459c80..b596837a1527 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 3b97a5eae9e8..74173ce6aaf4 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 8420ed12491e..fdbc7f422ea5 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<<TIF_SYSCALL_TRACE)
 #define _TIF_NOTIFY_RESUME      (1<<TIF_NOTIFY_RESUME)
@@ -153,7 +152,6 @@ register unsigned long current_stack_pointer asm("esp") __attribute_used__;
 #define _TIF_SYSCALL_AUDIT      (1<<TIF_SYSCALL_AUDIT)
 #define _TIF_SECCOMP            (1<<TIF_SECCOMP)
 #define _TIF_RESTORE_SIGMASK    (1<<TIF_RESTORE_SIGMASK)
-#define _TIF_POLLING_NRFLAG     (1<<TIF_POLLING_NRFLAG)
 
 /* work to do on interrupt/exception return */
 #define _TIF_WORK_MASK \
@@ -170,6 +168,9 @@ register unsigned long current_stack_pointer asm("esp") __attribute_used__;
  * have to worry about atomic accesses.
  */
 #define TS_USEDFPU              0x0001  /* FPU was used by this task this quantum (SMP) */
+#define TS_POLLING              0x0002  /* True if in idle loop and not sleeping */
+
+#define tsk_is_polling(t) ((t)->thread_info->status & TS_POLLING)
 
 #endif /* __KERNEL__ */
 
diff --git a/include/asm-ia64/thread_info.h b/include/asm-ia64/thread_info.h
index e5392c4d30c6..8bc9869e5765 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 4ac0e0a36934..b5e88216fd80 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<<TIF_IRET)
 #define _TIF_SYSCALL_AUDIT      (1<<TIF_SYSCALL_AUDIT)
 #define _TIF_SECCOMP            (1<<TIF_SECCOMP)
-#define _TIF_POLLING_NRFLAG     (1<<TIF_POLLING_NRFLAG)
 #define _TIF_IA32               (1<<TIF_IA32)
 #define _TIF_FORK               (1<<TIF_FORK)
 #define _TIF_ABI_PENDING        (1<<TIF_ABI_PENDING)
@@ -137,6 +136,9 @@ static inline struct thread_info *stack_thread_info(void)
  */
 #define TS_USEDFPU              0x0001  /* FPU was used by this task this quantum (SMP) */
 #define TS_COMPAT               0x0002  /* 32bit syscall active */
+#define TS_POLLING              0x0004  /* true if in idle loop and not sleeping */
+
+#define tsk_is_polling(t) ((t)->thread_info->status & TS_POLLING)
 
 #endif /* __KERNEL__ */
 
diff --git a/kernel/sched.c b/kernel/sched.c
index f06d059edef5..7d1027a4dd21 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