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Correct elapsed time calculation

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Elapsed time calculation must always be be the current time minus a time in the past.  Not vice versa.

Also corrects and improves some comments.
This commit is contained in:
Gregory Nutt 2021-03-19 09:02:18 -06:00 committed by Xiang Xiao
parent 5b7dfa0213
commit 2208aabbc6
1 changed files with 26 additions and 13 deletions
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39
sched/sched/sched_sporadic.c
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@ -390,8 +390,8 @@ static int sporadic_replenish_start(FAR struct replenishment_s *repl)
* Start the delay prior to providing the replenishment.
*
* Input Parameters:
* tcb - Current thread's tCB
* repl - Replenishment timer to be used
* period - Delay to the timer expiration
* replenish - The replenish time to be applied after the delay
*
* Returned Value:
@ -487,11 +487,11 @@ static void sporadic_budget_expire(wdparm_t arg)
uint32_t unrealized;
/* The unrealized time is the interval from when the thread was
* suspended (or which the budget interval was started in the case
* suspended (or when the budget interval was started in the case
* that the thread was delayed for the entire interval).
*/
unrealized = sporadic->eventtime - clock_systime_ticks();
unrealized = clock_systime_ticks() - sporadic->eventtime;
if (unrealized > 0)
{
/* Allocate a new replenishment timer. This will limit us to the
@ -501,12 +501,19 @@ static void sporadic_budget_expire(wdparm_t arg)
repl = sporadic_alloc_repl(sporadic);
if (repl != NULL)
{
/* The delay is one half of the scheduler cycle relative to
* the suspend time. Hence, we subtract the unrealized amount.
*/
uint32_t period;
/* Calculate the delay to when replenishment interval begins.
* That time is one half of the scheduler cycle relative to
* the suspend time. The delay relative to the current time
* is then:
*
* repl_time = susp_time + repl_interval / 2;
* delay = repl_time - curr_time
* delay = susp_time - curr_time + repl_interval / 2
* delay = repl_interval / 2 - unrealized
*/
DEBUGASSERT(unrealized <= (sporadic->repl_period >> 1));
period = (sporadic->repl_period >> 1) - unrealized;
@ -1066,13 +1073,19 @@ int nxsched_resume_sporadic(FAR struct tcb_s *tcb)
repl = sporadic_alloc_repl(sporadic);
if (repl != NULL)
{
/* The delay is one half of the scheduler cycle relative
* to the suspend time. Hence, we subtract the unrealized.
* amount.
*/
uint32_t period;
/* Calculate the delay to when replenishment interval
* begins. That time is one half of the scheduler cycle
* relative to the suspend time. The delay relative to
* the current time is then:
*
* repl_time = susp_time + repl_interval / 2;
* delay = repl_time - curr_time
* delay = susp_time - curr_time + repl_interval / 2
* delay = repl_interval / 2 - unrealized
*/
DEBUGASSERT(unrealized <= (sporadic->repl_period >> 1));
period = (sporadic->repl_period >> 1) - unrealized;
@ -1102,7 +1115,7 @@ int nxsched_resume_sporadic(FAR struct tcb_s *tcb)
* Name: nxsched_suspend_sporadic
*
* Description:
* Called to when a thread with sporadic scheduling is suspended. In this
* Called when a thread with sporadic scheduling is suspended. In this
* case, there will be unaccounted for time from the time that the last
* when the task is resumed. All that we need to do here is remember
* that time that we were suspended.