sched: Unify load_balance{,_newidle}()
load_balance() and load_balance_newidle() look remarkably similar, one key point they differ in is the condition on when to active balance. So split out that logic into a separate function. One side effect is that previously load_balance_newidle() used to fail and return -1 under these conditions, whereas now it doesn't. I've not yet fully figured out the whole -1 return case for either load_balance{,_newidle}(). Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@elte.hu>
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@ -2816,6 +2816,39 @@ find_busiest_queue(struct sched_group *group, enum cpu_idle_type idle,
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/* Working cpumask for load_balance and load_balance_newidle. */
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/* Working cpumask for load_balance and load_balance_newidle. */
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static DEFINE_PER_CPU(cpumask_var_t, load_balance_tmpmask);
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static DEFINE_PER_CPU(cpumask_var_t, load_balance_tmpmask);
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static int need_active_balance(struct sched_domain *sd, int sd_idle, int idle)
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{
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if (idle == CPU_NEWLY_IDLE) {
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/*
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* The only task running in a non-idle cpu can be moved to this
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* cpu in an attempt to completely freeup the other CPU
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* package.
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*
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* The package power saving logic comes from
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* find_busiest_group(). If there are no imbalance, then
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* f_b_g() will return NULL. However when sched_mc={1,2} then
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* f_b_g() will select a group from which a running task may be
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* pulled to this cpu in order to make the other package idle.
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* If there is no opportunity to make a package idle and if
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* there are no imbalance, then f_b_g() will return NULL and no
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* action will be taken in load_balance_newidle().
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*
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* Under normal task pull operation due to imbalance, there
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* will be more than one task in the source run queue and
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* move_tasks() will succeed. ld_moved will be true and this
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* active balance code will not be triggered.
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*/
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if (!sd_idle && sd->flags & SD_SHARE_CPUPOWER &&
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!test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
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return 0;
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if (sched_mc_power_savings < POWERSAVINGS_BALANCE_WAKEUP)
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return 0;
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}
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return unlikely(sd->nr_balance_failed > sd->cache_nice_tries+2);
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}
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/*
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/*
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* Check this_cpu to ensure it is balanced within domain. Attempt to move
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* Check this_cpu to ensure it is balanced within domain. Attempt to move
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* tasks if there is an imbalance.
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* tasks if there is an imbalance.
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@ -2902,8 +2935,7 @@ redo:
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schedstat_inc(sd, lb_failed[idle]);
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schedstat_inc(sd, lb_failed[idle]);
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sd->nr_balance_failed++;
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sd->nr_balance_failed++;
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if (unlikely(sd->nr_balance_failed > sd->cache_nice_tries+2)) {
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if (need_active_balance(sd, sd_idle, idle)) {
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raw_spin_lock_irqsave(&busiest->lock, flags);
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raw_spin_lock_irqsave(&busiest->lock, flags);
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/* don't kick the migration_thread, if the curr
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/* don't kick the migration_thread, if the curr
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@ -3049,66 +3081,37 @@ redo:
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int active_balance = 0;
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int active_balance = 0;
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schedstat_inc(sd, lb_failed[CPU_NEWLY_IDLE]);
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schedstat_inc(sd, lb_failed[CPU_NEWLY_IDLE]);
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if (!sd_idle && sd->flags & SD_SHARE_CPUPOWER &&
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sd->nr_balance_failed++;
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!test_sd_parent(sd, SD_POWERSAVINGS_BALANCE))
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return -1;
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if (sched_mc_power_savings < POWERSAVINGS_BALANCE_WAKEUP)
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if (need_active_balance(sd, sd_idle, CPU_NEWLY_IDLE)) {
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return -1;
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double_lock_balance(this_rq, busiest);
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if (sd->nr_balance_failed++ < 2)
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/*
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return -1;
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* don't kick the migration_thread, if the curr
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* task on busiest cpu can't be moved to this_cpu
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*/
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if (!cpumask_test_cpu(this_cpu,
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&busiest->curr->cpus_allowed)) {
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double_unlock_balance(this_rq, busiest);
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all_pinned = 1;
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return ld_moved;
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}
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/*
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if (!busiest->active_balance) {
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* The only task running in a non-idle cpu can be moved to this
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busiest->active_balance = 1;
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* cpu in an attempt to completely freeup the other CPU
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busiest->push_cpu = this_cpu;
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* package. The same method used to move task in load_balance()
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active_balance = 1;
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* have been extended for load_balance_newidle() to speedup
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}
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* consolidation at sched_mc=POWERSAVINGS_BALANCE_WAKEUP (2)
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*
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* The package power saving logic comes from
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* find_busiest_group(). If there are no imbalance, then
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* f_b_g() will return NULL. However when sched_mc={1,2} then
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* f_b_g() will select a group from which a running task may be
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* pulled to this cpu in order to make the other package idle.
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* If there is no opportunity to make a package idle and if
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* there are no imbalance, then f_b_g() will return NULL and no
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* action will be taken in load_balance_newidle().
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*
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* Under normal task pull operation due to imbalance, there
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* will be more than one task in the source run queue and
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* move_tasks() will succeed. ld_moved will be true and this
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* active balance code will not be triggered.
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*/
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/* Lock busiest in correct order while this_rq is held */
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double_lock_balance(this_rq, busiest);
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/*
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* don't kick the migration_thread, if the curr
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* task on busiest cpu can't be moved to this_cpu
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*/
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if (!cpumask_test_cpu(this_cpu, &busiest->curr->cpus_allowed)) {
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double_unlock_balance(this_rq, busiest);
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double_unlock_balance(this_rq, busiest);
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all_pinned = 1;
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/*
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return ld_moved;
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* Should not call ttwu while holding a rq->lock
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*/
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raw_spin_unlock(&this_rq->lock);
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if (active_balance)
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wake_up_process(busiest->migration_thread);
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raw_spin_lock(&this_rq->lock);
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}
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}
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if (!busiest->active_balance) {
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busiest->active_balance = 1;
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busiest->push_cpu = this_cpu;
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active_balance = 1;
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}
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double_unlock_balance(this_rq, busiest);
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/*
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* Should not call ttwu while holding a rq->lock
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*/
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raw_spin_unlock(&this_rq->lock);
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if (active_balance)
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wake_up_process(busiest->migration_thread);
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raw_spin_lock(&this_rq->lock);
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} else
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} else
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sd->nr_balance_failed = 0;
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sd->nr_balance_failed = 0;
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