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Fix a very subtle bug that would cause a yielding thread to be scheduled twice in a row even if others were woken and one of them should be selected. Evaluate next thread _after_ waking checks to keep fairness.

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git-svn-id: svn://svn.rockbox.org/rockbox/trunk@16444 a1c6a512-1295-4272-9138-f99709370657
This commit is contained in:
Michael Sevakis 2008-02-28 17:40:18 +00:00
parent 7cbf70cbf2
commit bbe3f1f61c
1 changed files with 11 additions and 6 deletions
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17
firmware/thread.c
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@ -1590,14 +1590,10 @@ void switch_thread(struct thread_entry *old)
{ {
const unsigned int core = CURRENT_CORE; const unsigned int core = CURRENT_CORE;
struct thread_entry *thread = cores[core].running; struct thread_entry *thread = cores[core].running;
struct thread_entry *block = old;
if (old == NULL) if (block == NULL)
{
/* Move to next thread */
old = thread; old = thread;
cores[core].running = old->l.next;
}
/* else running list is already at next thread */
#ifdef RB_PROFILE #ifdef RB_PROFILE
profile_thread_stopped(old - threads); profile_thread_stopped(old - threads);
@ -1625,6 +1621,9 @@ void switch_thread(struct thread_entry *old)
#ifdef HAVE_PRIORITY_SCHEDULING #ifdef HAVE_PRIORITY_SCHEDULING
/* Select the new task based on priorities and the last time a process /* Select the new task based on priorities and the last time a process
* got CPU time. */ * got CPU time. */
if (block == NULL)
thread = thread->l.next;
for (;;) for (;;)
{ {
int priority = thread->priority; int priority = thread->priority;
@ -1645,6 +1644,12 @@ void switch_thread(struct thread_entry *old)
/* Reset the value of thread's last running time to the current time. */ /* Reset the value of thread's last running time to the current time. */
thread->last_run = current_tick; thread->last_run = current_tick;
#else
if (block == NULL)
{
thread = thread->l.next;
cores[core].running = thread;
}
#endif /* HAVE_PRIORITY_SCHEDULING */ #endif /* HAVE_PRIORITY_SCHEDULING */
/* And finally give control to the next thread. */ /* And finally give control to the next thread. */