[lkml]   [2003]   [Aug]   [18]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
    SubjectRe: [PATCH] O16int for interactivity

    Timothy Miller wrote:

    > Con Kolivas wrote:
    >>> A hardware timer interrupt happens at timeslice granularity. If the
    >>> interrupt occurs, but the timeslice is not expired, then NORMALLY, the
    >>> ISR would just return right back to the running task, but sometimes, it
    >>> might decided to end the timeslice early and run some other task.
    >>> Right?
    >> No, the timeslice granularity is a hard cut off where a task gets
    >> rescheduled and put at the back of the queue again. If there is no
    >> other task of equal or better priority it will just start again.
    > Hmmm... I'm still having trouble making sense of this.
    > So, it seems that you're saying that all tasks, regardless of
    > timeslice length, are interrupted every 10ms (at 100hz).

    Interrupted - in that scheduler_tick is run, yes. They don't get switched.

    > If another task exists at a higher priority, then it gets run at
    > that point.

    Well loosely, yes. Actually, it happens if the task exists and is "running",
    and has timeslice left. That only happens in scheduler_tick when the
    task has finished its timeslice and the priority arrays are about to be
    switched. The required conditions for preemption can also occur when a task
    is being woken up, (after sleeping or newly forked).

    > However, if there is more than one task at a given priority level,
    > then they will not round-robin until the current task has used up all
    > of its timeslice (some integer multiple of 10ms).

    Thats right. Although I think Con or Ingo recently changed this in mm

    > Am I finally correct, or do I still have it wrong? :)

    Sounds right to me.

    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to
    More majordomo info at
    Please read the FAQ at

     \ /
      Last update: 2005-03-22 13:47    [W:0.023 / U:59.500 seconds]
    ©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site