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authorPaul E. McKenney <paul.mckenney@linaro.org>2012-01-06 23:11:30 +0100
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2012-02-21 18:03:25 +0100
commit486e259340fc4c60474f2c14703e3b3634bb58ca (patch)
tree70a58702194588fa0773463523f72c682785d040 /kernel/rcutree.h
parentrcu: Add diagnostic for misaligned rcu_head structures (diff)
downloadlinux-486e259340fc4c60474f2c14703e3b3634bb58ca.tar.xz
linux-486e259340fc4c60474f2c14703e3b3634bb58ca.zip
rcu: Avoid waking up CPUs having only kfree_rcu() callbacks
When CONFIG_RCU_FAST_NO_HZ is enabled, RCU will allow a given CPU to enter dyntick-idle mode even if it still has RCU callbacks queued. RCU avoids system hangs in this case by scheduling a timer for several jiffies in the future. However, if all of the callbacks on that CPU are from kfree_rcu(), there is no reason to wake the CPU up, as it is not a problem to defer freeing of memory. This commit therefore tracks the number of callbacks on a given CPU that are from kfree_rcu(), and avoids scheduling the timer if all of a given CPU's callbacks are from kfree_rcu(). 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.h3
1 files changed, 2 insertions, 1 deletions
diff --git a/kernel/rcutree.h b/kernel/rcutree.h
index fddff92d6676..af2af3cc5e65 100644
--- a/kernel/rcutree.h
+++ b/kernel/rcutree.h
@@ -265,7 +265,8 @@ struct rcu_data {
*/
struct rcu_head *nxtlist;
struct rcu_head **nxttail[RCU_NEXT_SIZE];
- long qlen; /* # of queued callbacks */
+ long qlen_lazy; /* # of lazy queued callbacks */
+ long qlen; /* # of queued callbacks, incl lazy */
long qlen_last_fqs_check;
/* qlen at last check for QS forcing */
unsigned long n_cbs_invoked; /* count of RCU cbs invoked. */