lkml.org 
[lkml]   [2017]   [Mar]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[RFC v5 5/9] sched/deadline: do not reclaim the whole CPU bandwidth
    Date
    From: Luca Abeni <luca.abeni@santannapisa.it>

    Original GRUB tends to reclaim 100% of the CPU time... And this
    allows a CPU hog to starve non-deadline tasks.
    To address this issue, allow the scheduler to reclaim only a
    specified fraction of CPU time.

    Signed-off-by: Luca Abeni <luca.abeni@santannapisa.it>
    Tested-by: Daniel Bristot de Oliveira <bristot@redhat.com>
    ---
    kernel/sched/core.c | 6 ++++++
    kernel/sched/deadline.c | 7 ++++++-
    kernel/sched/sched.h | 6 ++++++
    3 files changed, 18 insertions(+), 1 deletion(-)

    diff --git a/kernel/sched/core.c b/kernel/sched/core.c
    index 20c62e7..efa88eb 100644
    --- a/kernel/sched/core.c
    +++ b/kernel/sched/core.c
    @@ -6716,6 +6716,12 @@ static void sched_dl_do_global(void)
    raw_spin_unlock_irqrestore(&dl_b->lock, flags);

    rcu_read_unlock_sched();
    + if (dl_b->bw == -1)
    + cpu_rq(cpu)->dl.deadline_bw_inv = 1 << 8;
    + else
    + cpu_rq(cpu)->dl.deadline_bw_inv =
    + to_ratio(global_rt_runtime(),
    + global_rt_period()) >> 12;
    }
    }

    diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
    index 6035311..e964051 100644
    --- a/kernel/sched/deadline.c
    +++ b/kernel/sched/deadline.c
    @@ -212,6 +212,11 @@ void init_dl_rq(struct dl_rq *dl_rq)
    #else
    init_dl_bw(&dl_rq->dl_bw);
    #endif
    + if (global_rt_runtime() == RUNTIME_INF)
    + dl_rq->deadline_bw_inv = 1 << 8;
    + else
    + dl_rq->deadline_bw_inv =
    + to_ratio(global_rt_runtime(), global_rt_period()) >> 12;
    }

    #ifdef CONFIG_SMP
    @@ -871,7 +876,7 @@ extern bool sched_rt_bandwidth_account(struct rt_rq *rt_rq);
    */
    u64 grub_reclaim(u64 delta, struct rq *rq)
    {
    - return (delta * rq->dl.running_bw) >> 20;
    + return (delta * rq->dl.running_bw * rq->dl.deadline_bw_inv) >> 20 >> 8;
    }

    /*
    diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
    index 57bb79b..141549b 100644
    --- a/kernel/sched/sched.h
    +++ b/kernel/sched/sched.h
    @@ -565,6 +565,12 @@ struct dl_rq {
    * task blocks
    */
    u64 running_bw;
    +
    + /*
    + * Inverse of the fraction of CPU utilization that can be reclaimed
    + * by the GRUB algorithm.
    + */
    + u64 deadline_bw_inv;
    };

    #ifdef CONFIG_SMP
    --
    2.7.4
    \
     
     \ /
      Last update: 2017-03-23 20:53    [W:6.042 / U:0.272 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site