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| author | Paul E. McKenney <paul.mckenney@linaro.org> | 2012-01-06 14:11:30 -0800 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2012-02-21 09:03:25 -0800 |
| commit | 486e259340fc4c60474f2c14703e3b3634bb58ca (patch) | |
| tree | 70a58702194588fa0773463523f72c682785d040 /kernel/rcutiny.c | |
| parent | 0bb7b59d6e2b8440cd7097097dd4bbfc4d76ed07 (diff) | |
| download | lwn-486e259340fc4c60474f2c14703e3b3634bb58ca.tar.gz lwn-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/rcutiny.c')
| -rw-r--r-- | kernel/rcutiny.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/rcutiny.c b/kernel/rcutiny.c index 8e00d461911e..4eb34fcc2a75 100644 --- a/kernel/rcutiny.c +++ b/kernel/rcutiny.c @@ -258,7 +258,7 @@ static void __rcu_process_callbacks(struct rcu_ctrlblk *rcp) /* If no RCU callbacks ready to invoke, just return. */ if (&rcp->rcucblist == rcp->donetail) { - RCU_TRACE(trace_rcu_batch_start(rcp->name, 0, -1)); + RCU_TRACE(trace_rcu_batch_start(rcp->name, 0, 0, -1)); RCU_TRACE(trace_rcu_batch_end(rcp->name, 0, ACCESS_ONCE(rcp->rcucblist), need_resched(), @@ -269,7 +269,7 @@ static void __rcu_process_callbacks(struct rcu_ctrlblk *rcp) /* Move the ready-to-invoke callbacks to a local list. */ local_irq_save(flags); - RCU_TRACE(trace_rcu_batch_start(rcp->name, 0, -1)); + RCU_TRACE(trace_rcu_batch_start(rcp->name, 0, rcp->qlen, -1)); list = rcp->rcucblist; rcp->rcucblist = *rcp->donetail; *rcp->donetail = NULL; |