[PATCH] sched: less newidle locking
Similarly to the earlier change in load_balance, only lock the runqueue in load_balance_newidle if the busiest queue found has a nr_running > 1. This will reduce frequency of expensive remote runqueue lock aquisitions in the schedule() path on some workloads. Signed-off-by: Nick Piggin <npiggin@suse.de> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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@ -2104,8 +2104,7 @@ static int load_balance(int this_cpu, runqueue_t *this_rq,
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*/
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*/
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double_lock_balance(this_rq, busiest);
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double_lock_balance(this_rq, busiest);
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nr_moved = move_tasks(this_rq, this_cpu, busiest,
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nr_moved = move_tasks(this_rq, this_cpu, busiest,
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imbalance, sd, idle,
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imbalance, sd, idle, &all_pinned);
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&all_pinned);
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spin_unlock(&busiest->lock);
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spin_unlock(&busiest->lock);
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/* All tasks on this runqueue were pinned by CPU affinity */
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/* All tasks on this runqueue were pinned by CPU affinity */
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@ -2200,18 +2199,22 @@ static int load_balance_newidle(int this_cpu, runqueue_t *this_rq,
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BUG_ON(busiest == this_rq);
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BUG_ON(busiest == this_rq);
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/* Attempt to move tasks */
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double_lock_balance(this_rq, busiest);
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schedstat_add(sd, lb_imbalance[NEWLY_IDLE], imbalance);
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schedstat_add(sd, lb_imbalance[NEWLY_IDLE], imbalance);
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nr_moved = move_tasks(this_rq, this_cpu, busiest,
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nr_moved = 0;
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if (busiest->nr_running > 1) {
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/* Attempt to move tasks */
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double_lock_balance(this_rq, busiest);
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nr_moved = move_tasks(this_rq, this_cpu, busiest,
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imbalance, sd, NEWLY_IDLE, NULL);
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imbalance, sd, NEWLY_IDLE, NULL);
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spin_unlock(&busiest->lock);
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}
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if (!nr_moved)
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if (!nr_moved)
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schedstat_inc(sd, lb_failed[NEWLY_IDLE]);
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schedstat_inc(sd, lb_failed[NEWLY_IDLE]);
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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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spin_unlock(&busiest->lock);
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return nr_moved;
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return nr_moved;
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out_balanced:
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out_balanced:
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