Re: [Eas-dev] [PATCH 2/3] sched/fair: Refactor nohz blocked load udpates

Hi Brendan,

On 23 October 2017 at 15:32, Brendan Jackman brendan.jackman@arm.com wrote:

By moving the call to update_blocked_averages outside of rebalance_domains, we can avoid the use of CPU_MAX_IDLE_TYPES as a marker for aborting the load balance.

Vincent, if you agree with this I'll squash it into the parent before posting to LKML

Looks good to me

Vincent

---

kernel/sched/fair.c | 36 ++++++++++++------------------------ 1 file changed, 12 insertions(+), 24 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index cf27fa6548af..9085caf49c76 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -8816,19 +8816,6 @@ static void rebalance_domains(struct rq *rq, enum cpu_idle_type idle) int need_serialize, need_decay = 0; u64 max_cost = 0;

•   update_blocked_averages(cpu);
  

-#ifdef CONFIG_NO_HZ_COMMON

•   if ((idle == CPU_MAX_IDLE_TYPES) ||
  

•                   test_bit(NOHZ_STATS_KICK, nohz_flags(cpu))) {
  

•           /*
  

•            * We only want to update blocked load and shares which has
  

•            * just been done above
  

•            */
  

•           return;
  

•   }
  

-#endif

•   rcu_read_lock();
    for_each_domain(cpu, sd) {
            /*
  

@@ -8954,15 +8941,6 @@ static void nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle) nohz.next_update = jiffies + msecs_to_jiffies(LOAD_AVG_PERIOD); rcu_read_unlock();

•   /*
  

•    * This idle load balance softirq has been triggered only to update the
  

•    * blocked load and shares of ilde CPUs. Set the idle state to an
  

•    * undefined state to the load balance will be aborted just after the
  

•    * update of blocked load
  

•    */
  

•   if (test_bit(NOHZ_STATS_KICK, nohz_flags(this_cpu)))
  

•           idle = CPU_MAX_IDLE_TYPES;
  

•   for_each_cpu(balance_cpu, nohz.idle_cpus_mask) {
            if (balance_cpu == this_cpu || !idle_cpu(balance_cpu))
                    continue;
  

@@ -8989,7 +8967,15 @@ static void nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle) cpu_load_update_idle(rq); rq_unlock_irq(rq, &rf);

•                   rebalance_domains(rq, idle);
  

•                   update_blocked_averages(balance_cpu);
  

•                   /*
  

•                    * This idle load balance softirq may have been
  

•                    * triggered only to update the blocked load and shares
  

•                    * of idle CPUs (which we have just done for
  

•                    * balance_cpu). In that case skip the actual balance.
  

•                    */
  

•                   if (!test_bit(NOHZ_STATS_KICK, nohz_flags(this_cpu)))
  

•                           rebalance_domains(rq, idle);
            }
  
            if (time_after(next_balance, rq->next_balance)) {
  

@@ -9123,7 +9109,9 @@ static __latent_entropy void run_rebalance_domains(struct softirq_action *h) * and abort nohz_idle_balance altogether if we pull some load. */ nohz_idle_balance(this_rq, idle);

•   rebalance_domains(this_rq, idle);
  

•   update_blocked_averages(this_rq->cpu);
  

•   if (!test_bit(NOHZ_STATS_KICK, nohz_flags(this_rq->cpu)))
  

•           rebalance_domains(this_rq, idle);
  

#ifdef CONFIG_NO_HZ_COMMON clear_bit(NOHZ_STATS_KICK, nohz_flags(this_rq->cpu));

#endif

2.14.1