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Threads of PRIORITY_REALTIME and above are no longer subject to being switched away based upon aging of lower priority threads. Now, recommend a thread switch in wakeup_thread of any thread of higher priority is ready to run.

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git-svn-id: svn://svn.rockbox.org/rockbox/trunk@25666 a1c6a512-1295-4272-9138-f99709370657
This commit is contained in:
Michael Sevakis 2010-04-18 09:43:59 +00:00
parent 1a10c75c03
commit d6cd1bc58e
1 changed files with 18 additions and 10 deletions
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28
firmware/thread.c
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@ -2062,16 +2062,23 @@ void switch_thread(void)
/* This ridiculously simple method of aging seems to work
* suspiciously well. It does tend to reward CPU hogs (under
* yielding) but that's generally not desirable at all. On the
* plus side, it, relatively to other threads, penalizes excess
* yielding which is good if some high priority thread is
* performing no useful work such as polling for a device to be
* ready. Of course, aging is only employed when higher and lower
* priority threads are runnable. The highest priority runnable
* thread(s) are never skipped. */
* yielding) but that's generally not desirable at all. On
* the plus side, it, relatively to other threads, penalizes
* excess yielding which is good if some high priority thread
* is performing no useful work such as polling for a device
* to be ready. Of course, aging is only employed when higher
* and lower priority threads are runnable. The highest
* priority runnable thread(s) are never skipped unless a
* lower-priority process has aged sufficiently. Priorities
* of REALTIME class are run strictly according to priority
* thus are not subject to switchout due to lower-priority
* processes aging; they must give up the processor by going
* off the run list. */
if (LIKELY(priority <= max) ||
IF_NO_SKIP_YIELD( thread->skip_count == -1 || )
(diff = priority - max, ++thread->skip_count > diff*diff))
(priority > PRIORITY_REALTIME &&
(diff = priority - max,
++thread->skip_count > diff*diff)))
{
cores[core].running = thread;
break;
@ -2226,8 +2233,9 @@ unsigned int wakeup_thread(struct thread_entry **list)
current = bl->wakeup_protocol(thread);
}
if (current != NULL && thread->priority < current->priority
IF_COP( && thread->core == current->core ))
if (current != NULL &&
IF_COP( thread->core == current->core && )
find_first_set_bit(cores[current->core].rtr.mask) < current->priority)
{
/* Woken thread is higher priority and exists on the same CPU core;
* recommend a task switch. Knowing if this is an interrupt call