lkml.org 
[lkml]   [2012]   [Apr]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 30/41] sched: Update rq clock on nohz CPU before migrating tasks
    Date
    Because the sched_class::put_prev_task() callback of rt and fair
    classes are referring to the rq clock to update their runtime
    statistics. A CPU running in tickless mode may carry a stale value.
    We need to update it there.

    Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
    Cc: Alessio Igor Bogani <abogani@kernel.org>
    Cc: Andrew Morton <akpm@linux-foundation.org>
    Cc: Avi Kivity <avi@redhat.com>
    Cc: Chris Metcalf <cmetcalf@tilera.com>
    Cc: Christoph Lameter <cl@linux.com>
    Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
    Cc: Geoff Levand <geoff@infradead.org>
    Cc: Gilad Ben Yossef <gilad@benyossef.com>
    Cc: Hakan Akkan <hakanakkan@gmail.com>
    Cc: Ingo Molnar <mingo@kernel.org>
    Cc: Kevin Hilman <khilman@ti.com>
    Cc: Max Krasnyansky <maxk@qualcomm.com>
    Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Stephen Hemminger <shemminger@vyatta.com>
    Cc: Steven Rostedt <rostedt@goodmis.org>
    Cc: Sven-Thorsten Dietrich <thebigcorporation@gmail.com>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    ---
    kernel/sched/core.c | 6 ++++++
    kernel/sched/sched.h | 6 ++++++
    2 files changed, 12 insertions(+), 0 deletions(-)

    diff --git a/kernel/sched/core.c b/kernel/sched/core.c
    index d24da6b..a7e611a 100644
    --- a/kernel/sched/core.c
    +++ b/kernel/sched/core.c
    @@ -5166,6 +5166,12 @@ static void migrate_tasks(unsigned int dead_cpu)
    /* Ensure any throttled groups are reachable by pick_next_task */
    unthrottle_offline_cfs_rqs(rq);

    + /*
    + * ->put_prev_task() need to have an up-to-date value
    + * of rq->clock[_task]
    + */
    + update_nohz_rq_clock(rq);
    +
    for ( ; ; ) {
    /*
    * There's this thread running, bail when that's the only
    diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
    index b89f254..b463e82 100644
    --- a/kernel/sched/sched.h
    +++ b/kernel/sched/sched.h
    @@ -957,6 +957,12 @@ static inline void dec_nr_running(struct rq *rq)

    extern void update_rq_clock(struct rq *rq);

    +static inline void update_nohz_rq_clock(struct rq *rq)
    +{
    + if (cpuset_cpu_adaptive_nohz(cpu_of(rq)))
    + update_rq_clock(rq);
    +}
    +
    extern void activate_task(struct rq *rq, struct task_struct *p, int flags);
    extern void deactivate_task(struct rq *rq, struct task_struct *p, int flags);

    --
    1.7.5.4


    \
     
     \ /
      Last update: 2012-05-01 02:21    [W:0.044 / U:29.960 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site