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kernel/timeouts: add description of timeouts queued on the same tick

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Change-Id: I24ba889e3174b903ccea5309ad45e2b4d1755fe1
Signed-off-by: Benjamin Walsh <walsh.benj@gmail.com>
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Benjamin Walsh 2017-02-12 10:22:05 -05:00 • committed by Anas Nashif
commit 5d35dba73d
1 changed files with 15 additions and 0 deletions
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15
kernel/include/timeout_q.h
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@ -176,6 +176,21 @@ static inline void _dump_timeout_q(void)
* *
* Cannot handle timeout == 0 and timeout == K_FOREVER. * Cannot handle timeout == 0 and timeout == K_FOREVER.
* *
* If the new timeout is expiring on the same system clock tick as other
* timeouts already present in the _timeout_q, it is be _prepended_ to these
* timeouts. This allows exiting the loop sooner, which is good, since
* interrupts are locked while trying to find the insert point. Note that the
* timeouts are then processed in the _reverse order_ if they expire on the
* same tick.
*
* This should not cause problems to applications, unless they really expect
* two timeouts queued very close to one another to expire in the same order
* they were queued. This could be changed at the cost of potential longer
* interrupt latency.
*
* NOTE: The current implementation of the legacy semaphore feature depends on
* the timeouts being queued in reverse order.
*
* Must be called with interrupts locked. * Must be called with interrupts locked.
*/ */