From: Luca Abeni <luca.ab...@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.ab...@santannapisa.it> Tested-by: Daniel Bristot de Oliveira <bris...@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