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authorIngo Molnar <mingo@elte.hu>2011-01-14 15:30:16 +0100
committerIngo Molnar <mingo@elte.hu>2011-01-14 15:30:16 +0100
commit1161ec944916069ceec21c487e30247d9ff22857 (patch)
tree741385cbfde51286f502790cdfb77b1af2953944 /kernel
parentf123c98e7f168e949b283690693695f988332c3d (diff)
parentb24efdfdf679cf9b05947c531971905fc727dd40 (diff)
downloadop-kernel-dev-1161ec944916069ceec21c487e30247d9ff22857.zip
op-kernel-dev-1161ec944916069ceec21c487e30247d9ff22857.tar.gz
Merge branch 'rcu/next' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-2.6-rcu into core/urgent
Diffstat (limited to 'kernel')
-rw-r--r--kernel/rcutiny.c3
-rw-r--r--kernel/srcu.c15
2 files changed, 15 insertions, 3 deletions
diff --git a/kernel/rcutiny.c b/kernel/rcutiny.c
index 0344937..0c343b9 100644
--- a/kernel/rcutiny.c
+++ b/kernel/rcutiny.c
@@ -189,7 +189,8 @@ static int rcu_kthread(void *arg)
unsigned long flags;
for (;;) {
- wait_event(rcu_kthread_wq, have_rcu_kthread_work != 0);
+ wait_event_interruptible(rcu_kthread_wq,
+ have_rcu_kthread_work != 0);
morework = rcu_boost();
local_irq_save(flags);
work = have_rcu_kthread_work;
diff --git a/kernel/srcu.c b/kernel/srcu.c
index 98d8c1e..73ce23f 100644
--- a/kernel/srcu.c
+++ b/kernel/srcu.c
@@ -156,6 +156,16 @@ void __srcu_read_unlock(struct srcu_struct *sp, int idx)
EXPORT_SYMBOL_GPL(__srcu_read_unlock);
/*
+ * We use an adaptive strategy for synchronize_srcu() and especially for
+ * synchronize_srcu_expedited(). We spin for a fixed time period
+ * (defined below) to allow SRCU readers to exit their read-side critical
+ * sections. If there are still some readers after 10 microseconds,
+ * we repeatedly block for 1-millisecond time periods. This approach
+ * has done well in testing, so there is no need for a config parameter.
+ */
+#define SYNCHRONIZE_SRCU_READER_DELAY 10
+
+/*
* Helper function for synchronize_srcu() and synchronize_srcu_expedited().
*/
static void __synchronize_srcu(struct srcu_struct *sp, void (*sync_func)(void))
@@ -207,11 +217,12 @@ static void __synchronize_srcu(struct srcu_struct *sp, void (*sync_func)(void))
* will have finished executing. We initially give readers
* an arbitrarily chosen 10 microseconds to get out of their
* SRCU read-side critical sections, then loop waiting 1/HZ
- * seconds per iteration.
+ * seconds per iteration. The 10-microsecond value has done
+ * very well in testing.
*/
if (srcu_readers_active_idx(sp, idx))
- udelay(CONFIG_SRCU_SYNCHRONIZE_DELAY);
+ udelay(SYNCHRONIZE_SRCU_READER_DELAY);
while (srcu_readers_active_idx(sp, idx))
schedule_timeout_interruptible(1);
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