lkml.org 
[lkml]   [2000]   [Mar]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: new IRQ scalability changes in 2.3.48
    Andrea Arcangeli wrote:
    > >Note: In many cases, spinlock_irqsave doesn't need to do the
    > >spinlock_depth thing on UP. [..]
    >
    > It doesn't need that in SMP either.

    An interrupt on another process can wake up a task and set
    current->need_resched on this processor.

    > >[..] However, not all cases: the code in the
    > >lock region might wake up another task.
    >
    > If you wakeup another task you don't risk to get rescheduled before you
    > drop the lock.

    Waking up another task may set current->need_resched. But it can't
    actually reschedule until reaching the spin_unlock_irqsave. At that
    point or some low-latency time later, you need to reschedule to get low
    latency.

    -- Jamie

    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.rutgers.edu
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2005-03-22 13:57    [W:0.020 / U:59.368 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site