On Wed, Nov 10, 2010 at 09:19:26AM -0800, Randy Dunlap wrote:
> On Wed, 10 Nov 2010 14:07:19 +1100 Stephen Rothwell wrote:
>
> > Hi all,
> >
> > Changes since 20101109:
>
>
> when CONFIG_RCU_BOOST is not enabled:
>
> In file included from linux-next-20101110/kernel/rcutiny.c:53:
> linux-next-20101110/kernel/rcutiny_plugin.h: In function 'rcu_preempt_cpu_qs':
> linux-next-20101110/kernel/rcutiny_plugin.h:413: error: 'struct rcu_preempt_ctrlblk' has no member named 'n_normal_balk_blkd_tasks'
Hello, Randy,
Good catch! Could you please try the following patch?
Thanx, Paul
------------------------------------------------------------------------
diff --git a/kernel/rcutiny_plugin.h b/kernel/rcutiny_plugin.h
index 297aa35..8cd197c 100644
--- a/kernel/rcutiny_plugin.h
+++ b/kernel/rcutiny_plugin.h
@@ -297,9 +297,17 @@ static int rcu_boost(void)
* the current grace period, and, if so, tell the rcu_kthread_task to
* start boosting them. If there is an expedited boost in progress,
* we wait for it to complete.
+ *
+ * If there are no blocked readers blocking the current grace period,
+ * return 0 to let the caller know, otherwise return 1. Note that this
+ * return value is independent of whether or not boosting was done.
*/
-static void rcu_initiate_boost(void)
+static int rcu_initiate_boost(void)
{
+ if (!rcu_preempt_blocked_readers_cgp()) {
+ RCU_TRACE(rcu_preempt_ctrlblk.n_normal_balk_blkd_tasks++);
+ return 0;
+ }
if (rcu_preempt_ctrlblk.gp_tasks != NULL &&
rcu_preempt_ctrlblk.boost_tasks == NULL &&
rcu_preempt_ctrlblk.boosted_this_gp == 0 &&
@@ -309,6 +317,7 @@ static void rcu_initiate_boost(void)
RCU_TRACE(rcu_preempt_ctrlblk.n_normal_boosts++);
} else
RCU_TRACE(rcu_initiate_boost_trace());
+ return 1;
}
/*
@@ -353,10 +362,13 @@ static int rcu_boost(void)
}
/*
- * If there is no RCU priority boosting, we don't initiate boosting.
+ * If there is no RCU priority boosting, we don't initiate boosting,
+ * but we do indicate whether there are blocked readers blocking the
+ * current grace period.
*/
-static void rcu_initiate_boost(void)
+static int rcu_initiate_boost(void)
{
+ return rcu_preempt_blocked_readers_cgp();
}
/*
@@ -405,12 +417,12 @@ static void rcu_preempt_cpu_qs(void)
/* If there is no GP then there is nothing more to do. */
if (!rcu_preempt_gp_in_progress())
return;
- /* If there are blocked readers, go check up on boosting. */
- if (rcu_preempt_blocked_readers_cgp()) {
- rcu_initiate_boost();
+ /*
+ * Check up on boosting. If there are no readers blocking the
+ * current grace period, leave.
+ */
+ if (rcu_initiate_boost())
return;
- } else
- RCU_TRACE(rcu_preempt_ctrlblk.n_normal_balk_blkd_tasks++);
/* Advance callbacks. */
rcu_preempt_ctrlblk.completed = rcu_preempt_ctrlblk.gpnum;
--
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