diff options
author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2010-03-19 00:36:51 -0400 |
---|---|---|
committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2010-05-10 14:08:31 -0400 |
commit | d25eb9442bb2c38c1e742f0fa764d7132d72593f (patch) | |
tree | 0a2604a3b61ce7a0868c021ac945d9826e0d88f1 /kernel/rcutree.c | |
parent | 2b3fc35f6919344e3cf722dde8308f47235c0b70 (diff) |
rcu: substitute set_need_resched for sending resched IPIs
This patch adds a check to __rcu_pending() that does a local
set_need_resched() if the current CPU is holding up the current grace
period and if force_quiescent_state() will be called soon. The goal is
to reduce the probability that force_quiescent_state() will need to do
smp_send_reschedule(), which sends an IPI and is therefore more expensive
on most architectures.
Signed-off-by: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/rcutree.c')
-rw-r--r-- | kernel/rcutree.c | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/kernel/rcutree.c b/kernel/rcutree.c index 3ec8160fc75..e54c1235122 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c | |||
@@ -1499,6 +1499,16 @@ static int __rcu_pending(struct rcu_state *rsp, struct rcu_data *rdp) | |||
1499 | 1499 | ||
1500 | /* Is the RCU core waiting for a quiescent state from this CPU? */ | 1500 | /* Is the RCU core waiting for a quiescent state from this CPU? */ |
1501 | if (rdp->qs_pending) { | 1501 | if (rdp->qs_pending) { |
1502 | |||
1503 | /* | ||
1504 | * If force_quiescent_state() coming soon and this CPU | ||
1505 | * needs a quiescent state, and this is either RCU-sched | ||
1506 | * or RCU-bh, force a local reschedule. | ||
1507 | */ | ||
1508 | if (!rdp->preemptable && | ||
1509 | ULONG_CMP_LT(ACCESS_ONCE(rsp->jiffies_force_qs) - 1, | ||
1510 | jiffies)) | ||
1511 | set_need_resched(); | ||
1502 | rdp->n_rp_qs_pending++; | 1512 | rdp->n_rp_qs_pending++; |
1503 | return 1; | 1513 | return 1; |
1504 | } | 1514 | } |