Messages in this thread Patch in this message | | | From | Vincent Guittot <> | Subject | [PATCH v2 3/4] sched/fair: Wait before decaying max_newidle_lb_cost | Date | Fri, 15 Oct 2021 14:46:53 +0200 |
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Decay max_newidle_lb_cost only when it has not been updated for a while and ensure to not decay a recently changed value.
Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org> --- include/linux/sched/topology.h | 2 +- kernel/sched/fair.c | 8 +++++--- kernel/sched/topology.c | 2 +- 3 files changed, 7 insertions(+), 5 deletions(-)
diff --git a/include/linux/sched/topology.h b/include/linux/sched/topology.h index 8f0f778b7c91..9c8878f201ab 100644 --- a/include/linux/sched/topology.h +++ b/include/linux/sched/topology.h @@ -98,7 +98,7 @@ struct sched_domain { /* idle_balance() stats */ u64 max_newidle_lb_cost; - unsigned long next_decay_max_lb_cost; + unsigned long last_decay_max_lb_cost; u64 avg_scan_cost; /* select_idle_sibling */ diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 6b8065b72847..2967d13737b7 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -10265,10 +10265,10 @@ static void rebalance_domains(struct rq *rq, enum cpu_idle_type idle) * Decay the newidle max times here because this is a regular * visit to all the domains. Decay ~1% per second. */ - if (time_after(jiffies, sd->next_decay_max_lb_cost)) { + if (time_after(jiffies, sd->last_decay_max_lb_cost + HZ)) { sd->max_newidle_lb_cost = (sd->max_newidle_lb_cost * 253) / 256; - sd->next_decay_max_lb_cost = jiffies + HZ; + sd->last_decay_max_lb_cost = jiffies; need_decay = 1; } max_cost += sd->max_newidle_lb_cost; @@ -10912,8 +10912,10 @@ static int newidle_balance(struct rq *this_rq, struct rq_flags *rf) t1 = sched_clock_cpu(this_cpu); domain_cost = t1 - t0; - if (domain_cost > sd->max_newidle_lb_cost) + if (domain_cost > sd->max_newidle_lb_cost) { sd->max_newidle_lb_cost = domain_cost; + sd->last_decay_max_lb_cost = jiffies; + } curr_cost += domain_cost; t0 = t1; diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c index c56faae461d9..edd71649d579 100644 --- a/kernel/sched/topology.c +++ b/kernel/sched/topology.c @@ -1572,7 +1572,7 @@ sd_init(struct sched_domain_topology_level *tl, .last_balance = jiffies, .balance_interval = sd_weight, .max_newidle_lb_cost = 0, - .next_decay_max_lb_cost = jiffies, + .last_decay_max_lb_cost = jiffies, .child = child, #ifdef CONFIG_SCHED_DEBUG .name = tl->name, -- 2.17.1
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