score: Fix CPU time used by executing threads

The CPU time used of a thread was previously maintained per-processor
mostly during _Thread_Dispatch().  However, on SMP configurations the
actual processor of a thread is difficult to figure out since thread
dispatching is a highly asynchronous process (e.g. via inter-processor
interrupts).  Only the intended processor of a thread is known to the
scheduler easily.  Do the CPU usage accounting during thread heir
updates in the context of the scheduler operations.  Provide the
function _Thread_Get_CPU_time_used() to get the CPU usage of a thread
using proper locks to get a consistent value.

Close #2627.

1 files changed, 3 insertions, 20 deletions

diff --git a/cpukit/libmisc/cpuuse/cpuusagetop.c b/cpukit/libmisc/cpuuse/cpuusagetop.c
index 6355e4e636..9b928588c7 100644
--- a/cpukit/libmisc/cpuuse/cpuusagetop.c
+++ b/cpukit/libmisc/cpuuse/cpuusagetop.c
@@ -218,12 +218,14 @@ static void
 task_usage(Thread_Control* thread, void* arg)
 {
   rtems_cpu_usage_data* data = (rtems_cpu_usage_data*) arg;
-  Timestamp_Control     usage = thread->cpu_time_used;
+  Timestamp_Control     usage;
   Timestamp_Control     current = data->zero;
   int                   j;
 
   data->stack_size += thread->Start.Initial_stack.size;
 
+  _Thread_Get_CPU_time_used(thread, &usage);
+
   for (j = 0; j < data->last_task_count; j++)
   {
     if (thread == data->last_tasks[j])
@@ -497,25 +499,6 @@ rtems_cpuusage_top_thread (rtems_task_argument arg)
       current_usage = data->current_usage[i];
 
       /*
-       * If this is the currently executing thread, account for time since
-       * the last context switch.
-       */
-      if (_Thread_Get_time_of_last_context_switch(thread, &last))
-      {
-        Timestamp_Control used;
-        Timestamp_Control now;
-
-        /*
-         * Get the current uptime and assume we are not pre-empted to
-         * measure the time from the last switch this thread and now.
-         */
-        _TOD_Get_uptime(&now);
-        _Timestamp_Subtract(&last, &now, &used);
-        _Timestamp_Add_to(&usage, &used);
-        _Timestamp_Add_to(&current_usage, &used);
-      }
-
-      /*
        * Print the information
        */
       print_time(data, &usage, 19);