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authorPaul E. McKenney <paul.mckenney@linaro.org>2012-02-16 21:59:33 -0800
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2012-02-21 09:42:30 -0800
commit696a02cc16b182dd78b1f395ae336f449cc90f11 (patch)
tree5411af06d52a3f567e6b3fe592128d3fc0306be1 /kernel/rcutree_plugin.h
parentc3ce910b1456a45fa88959af3735bd6b285e54af (diff)
downloadop-kernel-dev-696a02cc16b182dd78b1f395ae336f449cc90f11.zip
op-kernel-dev-696a02cc16b182dd78b1f395ae336f449cc90f11.tar.gz
rcu: Hold off RCU_FAST_NO_HZ after timer posted
This commit handles workloads that transition quickly between idle and non-idle, and where the CPU's callbacks cannot be invoked, but where RCU does not have anything immediate for the CPU to do. Without this patch, the RCU_FAST_NO_HZ code can be invoked repeatedly on each entry to idle. The commit sets the per-CPU rcu_dyntick_holdoff variable to hold off further attempts for a tick. Reported-by: "Abou Gazala, Neven M" <neven.m.abou.gazala@intel.com> Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/rcutree_plugin.h')
-rw-r--r--kernel/rcutree_plugin.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h
index 392a651..c023464 100644
--- a/kernel/rcutree_plugin.h
+++ b/kernel/rcutree_plugin.h
@@ -2138,7 +2138,7 @@ static void rcu_prepare_for_idle(int cpu)
/* Can we go dyntick-idle despite still having callbacks? */
trace_rcu_prep_idle("Dyntick with callbacks");
per_cpu(rcu_dyntick_drain, cpu) = 0;
- per_cpu(rcu_dyntick_holdoff, cpu) = jiffies - 1;
+ per_cpu(rcu_dyntick_holdoff, cpu) = jiffies;
if (rcu_cpu_has_nonlazy_callbacks(cpu))
hrtimer_start(&per_cpu(rcu_idle_gp_timer, cpu),
rcu_idle_gp_wait, HRTIMER_MODE_REL);
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