sched: Save some hrtick_start_fair cycles
hrtick_start_fair() shows up in profiles even when disabled. v3.0.6 taskset -c 3 pipe-test PerfTop: 997 irqs/sec kernel:89.5% exact: 0.0% [1000Hz cycles], (all, CPU: 3) ------------------------------------------------------------------------------------------------ Virgin Patched samples pcnt function samples pcnt function _______ _____ ___________________________ _______ _____ ___________________________ 2880.00 10.2% __schedule 3136.00 11.3% __schedule 1634.00 5.8% pipe_read 1615.00 5.8% pipe_read 1458.00 5.2% system_call 1534.00 5.5% system_call 1382.00 4.9% _raw_spin_lock_irqsave 1412.00 5.1% _raw_spin_lock_irqsave 1202.00 4.3% pipe_write 1255.00 4.5% copy_user_generic_string 1164.00 4.1% copy_user_generic_string 1241.00 4.5% __switch_to 1097.00 3.9% __switch_to 929.00 3.3% mutex_lock 872.00 3.1% mutex_lock 846.00 3.0% mutex_unlock 687.00 2.4% mutex_unlock 804.00 2.9% pipe_write 682.00 2.4% native_sched_clock 713.00 2.6% native_sched_clock 643.00 2.3% system_call_after_swapgs 653.00 2.3% _raw_spin_unlock_irqrestore 617.00 2.2% sched_clock_local 633.00 2.3% fsnotify 612.00 2.2% fsnotify 605.00 2.2% sched_clock_local 596.00 2.1% _raw_spin_unlock_irqrestore 593.00 2.1% system_call_after_swapgs 542.00 1.9% sysret_check 559.00 2.0% sysret_check 467.00 1.7% fget_light 472.00 1.7% fget_light 462.00 1.6% finish_task_switch 461.00 1.7% finish_task_switch 437.00 1.5% vfs_write 442.00 1.6% vfs_write 431.00 1.5% do_sync_write 428.00 1.5% do_sync_write 413.00 1.5% select_task_rq_fair 404.00 1.5% _raw_spin_lock_irq 386.00 1.4% update_curr 402.00 1.4% update_curr 385.00 1.4% rw_verify_area 389.00 1.4% do_sync_read 377.00 1.3% _raw_spin_lock_irq 378.00 1.4% vfs_read 369.00 1.3% do_sync_read 340.00 1.2% pipe_iov_copy_from_user 360.00 1.3% vfs_read 316.00 1.1% __wake_up_sync_key * 342.00 1.2% hrtick_start_fair 313.00 1.1% __wake_up_common Signed-off-by: Mike Galbraith <efault@gmx.de> [ fixed !CONFIG_SCHED_HRTICK borkage ] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/1321971607.6855.17.camel@marge.simson.net Signed-off-by: Ingo Molnar <mingo@elte.hu>
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@ -2137,7 +2137,7 @@ static void hrtick_start_fair(struct rq *rq, struct task_struct *p)
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WARN_ON(task_rq(p) != rq);
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if (hrtick_enabled(rq) && cfs_rq->nr_running > 1) {
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if (cfs_rq->nr_running > 1) {
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u64 slice = sched_slice(cfs_rq, se);
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u64 ran = se->sum_exec_runtime - se->prev_sum_exec_runtime;
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s64 delta = slice - ran;
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@ -2168,7 +2168,7 @@ static void hrtick_update(struct rq *rq)
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{
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struct task_struct *curr = rq->curr;
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if (curr->sched_class != &fair_sched_class)
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if (!hrtick_enabled(rq) || curr->sched_class != &fair_sched_class)
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return;
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if (cfs_rq_of(&curr->se)->nr_running < sched_nr_latency)
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@ -3031,6 +3031,7 @@ static struct task_struct *pick_next_task_fair(struct rq *rq)
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} while (cfs_rq);
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p = task_of(se);
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if (hrtick_enabled(rq))
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hrtick_start_fair(rq, p);
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return p;
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@ -885,6 +885,13 @@ static inline int hrtick_enabled(struct rq *rq)
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void hrtick_start(struct rq *rq, u64 delay);
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#else
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static inline int hrtick_enabled(struct rq *rq)
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{
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return 0;
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}
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#endif /* CONFIG_SCHED_HRTICK */
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#ifdef CONFIG_SMP
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