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| author | Frederic Weisbecker <fweisbec@gmail.com> | 2016-04-19 15:36:51 (GMT) |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2016-04-23 12:20:42 (GMT) |
| commit | 9fd81dd5ce0b12341c9f83346f8d32ac68bd3841 (patch) | |
| tree | 6b189e45a9048f4c328f8f4ad80cd42ed899f1e6 /kernel/sched/core.c | |
| parent | 1f41906a6fda1114debd3898668bd7ab6470ee41 (diff) | |
| download | linux-9fd81dd5ce0b12341c9f83346f8d32ac68bd3841.tar.xz | |
sched/fair: Optimize !CONFIG_NO_HZ_COMMON CPU load updates
Some code in CPU load update only concern NO_HZ configs but it is
built on all configurations. When NO_HZ isn't built, that code is harmless
but just happens to take some useless ressources in CPU and memory:
1) one useless field in struct rq
2) jiffies record on every tick that is never used (cpu_load_update_periodic)
3) decay_load_missed is called two times on every tick to eventually
return immediately with no action taken. And that function is dead
code.
For pure optimization purposes, lets conditionally build the NO_HZ
related code.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Byungchul Park <byungchul.park@lge.com>
Cc: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Luiz Capitulino <lcapitulino@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul E . McKenney <paulmck@linux.vnet.ibm.com>
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/1461080211-16271-1-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/sched/core.c')
| -rw-r--r-- | kernel/sched/core.c | 5 |
1 files changed, 2 insertions, 3 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index c98a268..71dffbb 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -7381,8 +7381,6 @@ void __init sched_init(void) for (j = 0; j < CPU_LOAD_IDX_MAX; j++) rq->cpu_load[j] = 0; - rq->last_load_update_tick = jiffies; - #ifdef CONFIG_SMP rq->sd = NULL; rq->rd = NULL; @@ -7401,12 +7399,13 @@ void __init sched_init(void) rq_attach_root(rq, &def_root_domain); #ifdef CONFIG_NO_HZ_COMMON + rq->last_load_update_tick = jiffies; rq->nohz_flags = 0; #endif #ifdef CONFIG_NO_HZ_FULL rq->last_sched_tick = 0; #endif -#endif +#endif /* CONFIG_SMP */ init_rq_hrtick(rq); atomic_set(&rq->nr_iowait, 0); } |