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authorPaul E. McKenney <paul.mckenney@linaro.org>2012-02-28 11:02:21 -0800
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2012-04-24 20:55:20 -0700
commitc57afe80db4e169135eb675acc2d241e26cc064e (patch)
treeec011600725a2884efdca6f4c187ea7e3fa4d277 /kernel/rcutree.h
parent2ee3dc80660ac8285a37e662fd91b2e45c46f06a (diff)
rcu: Make RCU_FAST_NO_HZ account for pauses out of idle
Both Steven Rostedt's new idle-capable trace macros and the RCU_NONIDLE() macro can cause RCU to momentarily pause out of idle without the rest of the system being involved. This can cause rcu_prepare_for_idle() to run through its state machine too quickly, which can in turn result in needless scheduling-clock interrupts. This commit therefore adds code to enable rcu_prepare_for_idle() to distinguish between an initial entry to idle on the one hand (which needs to advance the rcu_prepare_for_idle() state machine) and an idle reentry due to idle-capable trace macros and RCU_NONIDLE() on the other hand (which should avoid advancing the rcu_prepare_for_idle() state machine). Additional state is maintained to allow the timer to be correctly reposted when returning after a momentary pause out of idle, and even more state is maintained to detect when new non-lazy callbacks have been enqueued (which may require re-evaluation of the approach to idleness). 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.h')
-rw-r--r--kernel/rcutree.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/kernel/rcutree.h b/kernel/rcutree.h
index cdd1be0a4072..36ca28ecedc6 100644
--- a/kernel/rcutree.h
+++ b/kernel/rcutree.h
@@ -471,6 +471,7 @@ static void __cpuinit rcu_prepare_kthreads(int cpu);
static void rcu_prepare_for_idle_init(int cpu);
static void rcu_cleanup_after_idle(int cpu);
static void rcu_prepare_for_idle(int cpu);
+static void rcu_idle_count_callbacks_posted(void);
static void print_cpu_stall_info_begin(void);
static void print_cpu_stall_info(struct rcu_state *rsp, int cpu);
static void print_cpu_stall_info_end(void);