This fix adds a missing part in the [RFC 07/11].
It will be added in the next version.
Signed-off-by: Vincent Guittot vincent.guittot@linaro.org
---
kernel/sched_fair.c | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 044ffcc..b3a54f4 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -91,6 +91,8 @@ unsigned int __read_mostly
sysctl_sched_shares_window = 10000000UL;
static const struct sched_class fair_sched_class;
+static unsigned long __read_mostly max_load_balance_interval = HZ/10;
+
/**************************************************************
* CFS operations on generic schedulable entities:
*/
@@ -3887,8 +3889,6 @@ void select_nohz_load_balancer(int stop_tick)
static DEFINE_SPINLOCK(balancing);
-static unsigned long __read_mostly max_load_balance_interval = HZ/10;
-
/*
* Scale the max load_balance interval with the number of CPUs in the system.
* This trades load-balance latency on larger machines for less cross talk.
--
1.7.4.1
On 21 October 2011 18:57, Vincent Guittot
vincent.guittot@linaro.org wrote:
> With a lot of small tasks, the softirq sched is nearly never called
> when no_hz is enable. The load_balance is mainly called with
> the newly_idle mode which doesn't update the cpu_power.
> Add a next_update field which ensures a maximum update period when
> there is short activity
>
> Signed-off-by: Vincent Guittot
vincent.guittot@linaro.org
> ---
> include/linux/sched.h | 1 +
> kernel/sched_fair.c | 20 ++++++++++++++------
> 2 files changed, 15 insertions(+), 6 deletions(-)
>
> diff --git a/include/linux/sched.h b/include/linux/sched.h
> index 41d0237..8610921 100644
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -901,6 +901,7 @@ struct sched_group_power {
> * single CPU.
> */
> unsigned int power, power_orig;
> + unsigned long next_update;
> };
>
> struct sched_group {
> diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
> index bc8ee99..3961876 100644
> --- a/kernel/sched_fair.c
> +++ b/kernel/sched_fair.c
> @@ -2667,6 +2667,11 @@ static void update_group_power(struct sched_domain *sd, int cpu)
> struct sched_domain *child = sd->child;
> struct sched_group *group, *sdg = sd->groups;
> unsigned long power;
> + unsigned long interval;
> +
> + interval = msecs_to_jiffies(sd->balance_interval);
> + interval = clamp(interval, 1UL, max_load_balance_interval);
> + sdg->sgp->next_update = jiffies + interval;
>
> if (!child) {
> update_cpu_power(sd, cpu);
> @@ -2774,12 +2779,15 @@ static inline void update_sg_lb_stats(struct sched_domain *sd,
> * domains. In the newly idle case, we will allow all the cpu's
> * to do the newly idle load balance.
> */
> - if (idle != CPU_NEWLY_IDLE && local_group) {
> - if (balance_cpu != this_cpu) {
> - *balance = 0;
> - return;
> - }
> - update_group_power(sd, this_cpu);
> + if (local_group) {
> + if (idle != CPU_NEWLY_IDLE) {
> + if (balance_cpu != this_cpu) {
> + *balance = 0;
> + return;
> + }
> + update_group_power(sd, this_cpu);
> + } else if (time_after_eq(jiffies, group->sgp->next_update))
> + update_group_power(sd, this_cpu);
> }
>
> /* Adjust by relative CPU power of the group */
> --
> 1.7.4.1
>
>
