lkml.org 
[lkml]   [2011]   [Jan]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [RFC][PATCH 08/17] sched: Drop the rq argument to sched_class::select_task_rq()
    On 01/03, Peter Zijlstra wrote:
    >
    > On Wed, 2010-12-29 at 22:31 +0800, Yong Zhang wrote:
    > > > - /*
    > > > - * select_task_rq() can race against ->cpus_allowed
    > > > - */
    > > > - if (cpumask_test_cpu(dest_cpu, &p->cpus_allowed) &&
    > > > - likely(cpu_active(dest_cpu)) && migrate_task(p, rq)) {
    > > > + if (likely(cpu_active(dest_cpu)) && need_migrate_task(p)) {
    > >
    > > If we drop rq_lock, need_migrate_task() maybe return true but
    > > p is already running on other cpu. Thus we do a wrong migration
    > > call.
    >
    > Yeah, too bad.. ;-) exec load balancing is more an optimistic thing
    > anyway, if it got rebalanced under out feet we don't care.

    I don't understand this need_migrate_task() at all (with or without
    the patch). This task is current/running, it should always return T.

    I guess, migrate_task() was needed before to initialize migration_req.

    Oleg.



    \
     
     \ /
      Last update: 2011-01-03 16:09    [W:0.040 / U:33.196 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site