lkml.org 
[lkml]   [2021]   [Oct]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH v2 3/4] sched/fair: Wait before decaying max_newidle_lb_cost
Date
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
\
 
 \ /
  Last update: 2021-10-15 14:50    [W:0.083 / U:0.384 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site