diff options
| author | Vincent Guittot <vincent.guittot@linaro.org> | 2021-10-19 14:35:35 +0200 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2021-10-31 11:11:38 +0100 |
| commit | e60b56e46b384cee1ad34e6adc164d883049c6c3 (patch) | |
| tree | fbef67008a7ce5d24913b43f5df56d3629ed3de5 /kernel | |
| parent | 9d783c8dd112ad4b619e74e4bf57d2be0b400693 (diff) | |
| download | linux-e60b56e46b384cee1ad34e6adc164d883049c6c3.tar.gz | |
sched/fair: Wait before decaying max_newidle_lb_cost
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> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com> Acked-by: Mel Gorman <mgorman@suse.de> Link: https://lore.kernel.org/r/20211019123537.17146-4-vincent.guittot@linaro.org
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/sched/fair.c | 36 | ||||
| -rw-r--r-- | kernel/sched/topology.c | 2 |
2 files changed, 28 insertions, 10 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index c4c36865321b..e50fd751e1df 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -10239,6 +10239,30 @@ void update_max_interval(void) max_load_balance_interval = HZ*num_online_cpus()/10; } +static inline bool update_newidle_cost(struct sched_domain *sd, u64 cost) +{ + if (cost > sd->max_newidle_lb_cost) { + /* + * Track max cost of a domain to make sure to not delay the + * next wakeup on the CPU. + */ + sd->max_newidle_lb_cost = cost; + sd->last_decay_max_lb_cost = jiffies; + } else if (time_after(jiffies, sd->last_decay_max_lb_cost + HZ)) { + /* + * Decay the newidle max times by ~1% per second to ensure that + * it is not outdated and the current max cost is actually + * shorter. + */ + sd->max_newidle_lb_cost = (sd->max_newidle_lb_cost * 253) / 256; + sd->last_decay_max_lb_cost = jiffies; + + return true; + } + + return false; +} + /* * It checks each scheduling domain to see if it is due to be balanced, * and initiates a balancing operation if so. @@ -10262,14 +10286,9 @@ static void rebalance_domains(struct rq *rq, enum cpu_idle_type idle) for_each_domain(cpu, sd) { /* * Decay the newidle max times here because this is a regular - * visit to all the domains. Decay ~1% per second. + * visit to all the domains. */ - if (time_after(jiffies, sd->next_decay_max_lb_cost)) { - sd->max_newidle_lb_cost = - (sd->max_newidle_lb_cost * 253) / 256; - sd->next_decay_max_lb_cost = jiffies + HZ; - need_decay = 1; - } + need_decay = update_newidle_cost(sd, 0); max_cost += sd->max_newidle_lb_cost; /* @@ -10911,8 +10930,7 @@ 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) - sd->max_newidle_lb_cost = domain_cost; + update_newidle_cost(sd, domain_cost); curr_cost += domain_cost; t0 = t1; diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c index e81246787560..30169c7685b6 100644 --- a/kernel/sched/topology.c +++ b/kernel/sched/topology.c @@ -1568,7 +1568,7 @@ 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, |