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authorVatika Harlalka <vatikaharlalka@gmail.com>2015-09-01 16:50:59 +0200
committerIngo Molnar <mingo@kernel.org>2015-09-02 10:33:22 +0200
commit9642d18eee2cd169b60c6ac0f20bda745b5a3d1e (patch)
tree11ba961bc1366fd72d9ec7f732488f1574d15281 /kernel
parente713c80a4e49d4bed5324d24755e42bf01c87556 (diff)
downloadlinux-9642d18eee2cd169b60c6ac0f20bda745b5a3d1e.tar.bz2
nohz: Affine unpinned timers to housekeepers
The problem addressed in this patch is about affining unpinned timers. Adaptive or Full Dynticks CPUs are currently disturbed by unnecessary jitter due to firing of such timers on them. This patch will affine timers to online CPUs which are not full dynticks in NOHZ_FULL configured systems. It should not introduce overhead in nohz full off case due to static keys. Signed-off-by: Vatika Harlalka <vatikaharlalka@gmail.com> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com> Acked-by: Thomas Gleixner <tglx@linutronix.de> Cc: Chris Metcalf <cmetcalf@ezchip.com> Cc: Christoph Lameter <cl@linux.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1441119060-2230-2-git-send-email-fweisbec@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/sched/core.c7
1 files changed, 5 insertions, 2 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 8b864ecee0e1..0902e4d72671 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -623,18 +623,21 @@ int get_nohz_timer_target(void)
int i, cpu = smp_processor_id();
struct sched_domain *sd;
- if (!idle_cpu(cpu))
+ if (!idle_cpu(cpu) && is_housekeeping_cpu(cpu))
return cpu;
rcu_read_lock();
for_each_domain(cpu, sd) {
for_each_cpu(i, sched_domain_span(sd)) {
- if (!idle_cpu(i)) {
+ if (!idle_cpu(i) && is_housekeeping_cpu(cpu)) {
cpu = i;
goto unlock;
}
}
}
+
+ if (!is_housekeeping_cpu(cpu))
+ cpu = housekeeping_any_cpu();
unlock:
rcu_read_unlock();
return cpu;