lkml.org 
[lkml]   [2002]   [Jan]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: The O(1) scheduler breaks UML
    On Mon, 14 Jan 2002, Ingo Molnar wrote:

    >
    > On Sun, 13 Jan 2002, Davide Libenzi wrote:
    >
    > > > So, is it possible to enable IRQs across the call to _switch_to?
    > >
    > > Yes, this should work :
    > >
    > > if (likely(prev != next)) {
    > > rq->nr_switches++;
    > > rq->curr = next;
    > > next->cpu = prev->cpu;
    > > spin_unlock_irq(&rq->lock);
    > > context_switch(prev, next);
    > > } else
    > > spin_unlock_irq(&rq->lock);
    >
    > this change is incredibly broken on SMP - eg. what protects 'prev' from
    > being executed on another CPU prematurely. It's even broken on UP:
    > interrupt context that changes current->need_resched needs to be aware of
    > nonatomic context switches. See my previous mail.

    yup, true. no more schedule_tail()



    - Davide


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

    \
     
     \ /
      Last update: 2005-03-22 13:15    [W:0.020 / U:9.184 seconds]
    ©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site