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    SubjectRe: [PATCH] scheduler: domain: correctly initialize 'next_balance' in 'nohz' idle balancer
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    On Wed, 2012-03-07 at 14:44 -0800, Diwakar Tundlam wrote:
    > scheduler: domain: init next_balance in nohz_idle_balancer with jiffies

    That's already in the subject, no need to repeat that in the body.

    > The 'next_balance' field of 'nohz' idle balancer must be initialized
    > to jiffies. Since jiffies is initialized to negative 300 seconds the
    > 'nohz' idle balancer does not run for the first 300s (5mins) after
    > bootup. If no new processes are spawed or no idle cycles happen, the
    > load on the cpus will remain unbalanced for that duration.
    >
    > Signed-off-by: Diwakar Tundlam <dtundlam@nvidia.com>
    > ---
    > 1 files changed, 1 insertions(+), 0 deletions(-)
    >
    > diff -up sched/fair.c{.orig,}
    > --- sched/fair.c.orig 2012-03-07 08:33:03.000000000 -0800
    > +++ sched/fair.c 2012-03-07 13:50:30.787265795 -0800

    This doesn't work, patches should apply with -p1. I just read
    Documentation/SubmittingPatches and I must admit to that not being very
    clear.

    In any case, I can recommend to using quilt or git to create patches.

    I've hand edited the patch for now, but in future please learn to use
    either of these tools.

    Final patch for re{f,v}erence.. :-)
    ---
    Subject: scheduler: domain: correctly initialize 'next_balance' in 'nohz' idle balancer
    From: Diwakar Tundlam <dtundlam@nvidia.com>
    Date: Wed, 7 Mar 2012 14:44:26 -0800

    The 'next_balance' field of 'nohz' idle balancer must be initialized
    to jiffies. Since jiffies is initialized to negative 300 seconds the
    'nohz' idle balancer does not run for the first 300s (5mins) after
    bootup. If no new processes are spawed or no idle cycles happen, the
    load on the cpus will remain unbalanced for that duration.

    Signed-off-by: Diwakar Tundlam <dtundlam@nvidia.com>
    Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
    Link: http://lkml.kernel.org/r/1DD7BFEDD3147247B1355BEFEFE4665237994F30EF@HQMAIL04.nvidia.com
    ---
    kernel/sched/fair.c | 1 +
    1 file changed, 1 insertion(+)

    --- a/kernel/sched/fair.c
    +++ b/kernel/sched/fair.c
    @@ -5603,6 +5603,7 @@ __init void init_sched_fair_class(void)
    open_softirq(SCHED_SOFTIRQ, run_rebalance_domains);

    #ifdef CONFIG_NO_HZ
    + nohz.next_balance = jiffies;
    zalloc_cpumask_var(&nohz.idle_cpus_mask, GFP_NOWAIT);
    cpu_notifier(sched_ilb_notifier, 0);
    #endif


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