sched/fair: Reset nr_balance_failed after active balancing
To force a task migration during active balancing, nr_balance_failed is set to cache_nice_tries + 1. However nr_balance_failed is not reset. As a side effect, the next regular load balance under the same sd, a cache hot task might be migrated, just because nr_balance_failed count is high. Resetting nr_balance_failed after a successful active balance ensures that a hot task is not unreasonably migrated. This can be verified by looking at othe number of hot task migrations reported by /proc/schedstat. Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Rik van Riel <riel@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1458735884-30105-1-git-send-email-srikar@linux.vnet.ibm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
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@ -7399,10 +7399,7 @@ more_balance:
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&busiest->active_balance_work);
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&busiest->active_balance_work);
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}
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}
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/*
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/* We've kicked active balancing, force task migration. */
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* We've kicked active balancing, reset the failure
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* counter.
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*/
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sd->nr_balance_failed = sd->cache_nice_tries+1;
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sd->nr_balance_failed = sd->cache_nice_tries+1;
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}
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}
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} else
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} else
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@ -7637,10 +7634,13 @@ static int active_load_balance_cpu_stop(void *data)
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schedstat_inc(sd, alb_count);
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schedstat_inc(sd, alb_count);
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p = detach_one_task(&env);
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p = detach_one_task(&env);
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if (p)
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if (p) {
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schedstat_inc(sd, alb_pushed);
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schedstat_inc(sd, alb_pushed);
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else
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/* Active balancing done, reset the failure counter. */
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sd->nr_balance_failed = 0;
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} else {
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schedstat_inc(sd, alb_failed);
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schedstat_inc(sd, alb_failed);
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}
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}
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}
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rcu_read_unlock();
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rcu_read_unlock();
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out_unlock:
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out_unlock:
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