32 files changed, 892 insertions, 906 deletions

diff --git a/Documentation/scheduler/sched-arch.txt b/Documentation/scheduler/sched-arch.txt
index 28aa1075e291..b1b8587b86f0 100644
--- a/Documentation/scheduler/sched-arch.txt
+++ b/Documentation/scheduler/sched-arch.txt
@@ -17,16 +17,6 @@ you must `#define __ARCH_WANT_UNLOCKED_CTXSW` in a header file
 Unlocked context switches introduce only a very minor performance
 penalty to the core scheduler implementation in the CONFIG_SMP case.
 
-2. Interrupt status
-By default, the switch_to arch function is called with interrupts
-disabled. Interrupts may be enabled over the call if it is likely to
-introduce a significant interrupt latency by adding the line
-`#define __ARCH_WANT_INTERRUPTS_ON_CTXSW` in the same place as for
-unlocked context switches. This define also implies
-`__ARCH_WANT_UNLOCKED_CTXSW`. See arch/arm/include/asm/system.h for an
-example.
-
-
 CPU idle
 ========
 Your cpu_idle routines need to obey the following rules:
diff --git a/arch/Kconfig b/arch/Kconfig
index 1a7b468abf4a..a62965d057f6 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -304,4 +304,13 @@ config HAVE_RCU_USER_QS
           are already protected inside rcu_irq_enter/rcu_irq_exit() but
           preemption or signal handling on irq exit still need to be protected.
 
+config HAVE_VIRT_CPU_ACCOUNTING
+        bool
+
+config HAVE_IRQ_TIME_ACCOUNTING
+        bool
+        help
+          Archs need to ensure they use a high enough resolution clock to
+          support irq time accounting and then call enable_sched_clock_irqtime().
+
 source "kernel/gcov/Kconfig"
diff --git a/arch/ia64/Kconfig b/arch/ia64/Kconfig
index 310cf5781fad..3c720ef6c32d 100644
--- a/arch/ia64/Kconfig
+++ b/arch/ia64/Kconfig
@@ -25,6 +25,7 @@ config IA64
         select HAVE_GENERIC_HARDIRQS
         select HAVE_MEMBLOCK
         select HAVE_MEMBLOCK_NODE_MAP
+        select HAVE_VIRT_CPU_ACCOUNTING
         select ARCH_DISCARD_MEMBLOCK
         select GENERIC_IRQ_PROBE
         select GENERIC_PENDING_IRQ if SMP
@@ -340,17 +341,6 @@ config FORCE_MAX_ZONEORDER
         default "17" if HUGETLB_PAGE
         default "11"
 
-config VIRT_CPU_ACCOUNTING
-        bool "Deterministic task and CPU time accounting"
-        default n
-        help
-          Select this option to enable more accurate task and CPU time
-          accounting.  This is done by reading a CPU counter on each
-          kernel entry and exit and on transitions within the kernel
-          between system, softirq and hardirq state, so there is a
-          small performance impact.
-          If in doubt, say N here.
-
 config SMP
         bool "Symmetric multi-processing support"
         select USE_GENERIC_SMP_HELPERS
diff --git a/arch/ia64/include/asm/switch_to.h b/arch/ia64/include/asm/switch_to.h
index cb2412fcd17f..d38c7ea5eea5 100644
--- a/arch/ia64/include/asm/switch_to.h
+++ b/arch/ia64/include/asm/switch_to.h
@@ -30,13 +30,6 @@ extern struct task_struct *ia64_switch_to (void *next_task);
 extern void ia64_save_extra (struct task_struct *task);
 extern void ia64_load_extra (struct task_struct *task);
 
-#ifdef CONFIG_VIRT_CPU_ACCOUNTING
-extern void ia64_account_on_switch (struct task_struct *prev, struct task_struct *next);
-# define IA64_ACCOUNT_ON_SWITCH(p,n) ia64_account_on_switch(p,n)
-#else
-# define IA64_ACCOUNT_ON_SWITCH(p,n)
-#endif
-
 #ifdef CONFIG_PERFMON
   DECLARE_PER_CPU(unsigned long, pfm_syst_info);
 # define PERFMON_IS_SYSWIDE() (__get_cpu_var(pfm_syst_info) & 0x1)
@@ -49,7 +42,6 @@ extern void ia64_account_on_switch (struct task_struct *prev, struct task_struct
          || PERFMON_IS_SYSWIDE())
 
 #define __switch_to(prev,next,last) do {                                                         \
-        IA64_ACCOUNT_ON_SWITCH(prev, next);                                                      \
         if (IA64_HAS_EXTRA_STATE(prev))                                                          \
                 ia64_save_extra(prev);                                                           \
         if (IA64_HAS_EXTRA_STATE(next))                                                          \
diff --git a/arch/ia64/kernel/time.c b/arch/ia64/kernel/time.c
index ecc904b33c5f..80ff9acc5edf 100644
--- a/arch/ia64/kernel/time.c
+++ b/arch/ia64/kernel/time.c
@@ -83,32 +83,36 @@ static struct clocksource *itc_clocksource;
 
 extern cputime_t cycle_to_cputime(u64 cyc);
 
+static void vtime_account_user(struct task_struct *tsk)
+{
+        cputime_t delta_utime;
+        struct thread_info *ti = task_thread_info(tsk);
+
+        if (ti->ac_utime) {
+                delta_utime = cycle_to_cputime(ti->ac_utime);
+                account_user_time(tsk, delta_utime, delta_utime);
+                ti->ac_utime = 0;
+        }
+}
+
 /*
  * Called from the context switch with interrupts disabled, to charge all
  * accumulated times to the current process, and to prepare accounting on
  * the next process.
  */
-void ia64_account_on_switch(struct task_struct *prev, struct task_struct *next)
+void vtime_task_switch(struct task_struct *prev)
 {
         struct thread_info *pi = task_thread_info(prev);
-        struct thread_info *ni = task_thread_info(next);
-        cputime_t delta_stime, delta_utime;
-        __u64 now;
+        struct thread_info *ni = task_thread_info(current);
 
-        now = ia64_get_itc();
-
-        delta_stime = cycle_to_cputime(pi->ac_stime + (now - pi->ac_stamp));
         if (idle_task(smp_processor_id()) != prev)
-                account_system_time(prev, 0, delta_stime, delta_stime);
+                vtime_account_system(prev);
         else
-                account_idle_time(delta_stime);
+                vtime_account_idle(prev);