This commit adds kernel boot parameters for callback laziness, allowing
the RCU Tasks flavors to be individually adjusted.
Signed-off-by: Paul E. McKenney <[email protected]>
---
.../admin-guide/kernel-parameters.txt | 23 +++++++++++++++++++
kernel/rcu/tasks.h | 15 ++++++++++++
2 files changed, 38 insertions(+)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index a1457995fd41..a0f427e1a562 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -5293,6 +5293,29 @@
A change in value does not take effect until
the beginning of the next grace period.
+ rcupdate.rcu_tasks_lazy_ms= [KNL]
+ Set timeout in milliseconds RCU Tasks asynchronous
+ callback batching for call_rcu_tasks().
+ A negative value will take the default. A value
+ of zero will disable batching. Batching is
+ always disabled for synchronize_rcu_tasks().
+
+ rcupdate.rcu_tasks_rude_lazy_ms= [KNL]
+ Set timeout in milliseconds RCU Tasks
+ Rude asynchronous callback batching for
+ call_rcu_tasks_rude(). A negative value
+ will take the default. A value of zero will
+ disable batching. Batching is always disabled
+ for synchronize_rcu_tasks_rude().
+
+ rcupdate.rcu_tasks_trace_lazy_ms= [KNL]
+ Set timeout in milliseconds RCU Tasks
+ Trace asynchronous callback batching for
+ call_rcu_tasks_trace(). A negative value
+ will take the default. A value of zero will
+ disable batching. Batching is always disabled
+ for synchronize_rcu_tasks_trace().
+
rcupdate.rcu_self_test= [KNL]
Run the RCU early boot self tests
diff --git a/kernel/rcu/tasks.h b/kernel/rcu/tasks.h
index 7eae67fbe47c..28e986627e3f 100644
--- a/kernel/rcu/tasks.h
+++ b/kernel/rcu/tasks.h
@@ -1083,11 +1083,16 @@ void rcu_barrier_tasks(void)
}
EXPORT_SYMBOL_GPL(rcu_barrier_tasks);
+int rcu_tasks_lazy_ms = -1;
+module_param(rcu_tasks_lazy_ms, int, 0444);
+
static int __init rcu_spawn_tasks_kthread(void)
{
cblist_init_generic(&rcu_tasks);
rcu_tasks.gp_sleep = HZ / 10;
rcu_tasks.init_fract = HZ / 10;
+ if (rcu_tasks_lazy_ms >= 0)
+ rcu_tasks.lazy_jiffies = msecs_to_jiffies(rcu_tasks_lazy_ms);
rcu_tasks.pregp_func = rcu_tasks_pregp_step;
rcu_tasks.pertask_func = rcu_tasks_pertask;
rcu_tasks.postscan_func = rcu_tasks_postscan;
@@ -1236,10 +1241,15 @@ void rcu_barrier_tasks_rude(void)
}
EXPORT_SYMBOL_GPL(rcu_barrier_tasks_rude);
+int rcu_tasks_rude_lazy_ms = -1;
+module_param(rcu_tasks_rude_lazy_ms, int, 0444);
+
static int __init rcu_spawn_tasks_rude_kthread(void)
{
cblist_init_generic(&rcu_tasks_rude);
rcu_tasks_rude.gp_sleep = HZ / 10;
+ if (rcu_tasks_rude_lazy_ms >= 0)
+ rcu_tasks_rude.lazy_jiffies = msecs_to_jiffies(rcu_tasks_rude_lazy_ms);
rcu_spawn_tasks_kthread_generic(&rcu_tasks_rude);
return 0;
}
@@ -1856,6 +1866,9 @@ void rcu_barrier_tasks_trace(void)
}
EXPORT_SYMBOL_GPL(rcu_barrier_tasks_trace);
+int rcu_tasks_trace_lazy_ms = -1;
+module_param(rcu_tasks_trace_lazy_ms, int, 0444);
+
static int __init rcu_spawn_tasks_trace_kthread(void)
{
cblist_init_generic(&rcu_tasks_trace);
@@ -1870,6 +1883,8 @@ static int __init rcu_spawn_tasks_trace_kthread(void)
if (rcu_tasks_trace.init_fract <= 0)
rcu_tasks_trace.init_fract = 1;
}
+ if (rcu_tasks_trace_lazy_ms >= 0)
+ rcu_tasks_trace.lazy_jiffies = msecs_to_jiffies(rcu_tasks_trace_lazy_ms);
rcu_tasks_trace.pregp_func = rcu_tasks_trace_pregp_step;
rcu_tasks_trace.postscan_func = rcu_tasks_trace_postscan;
rcu_tasks_trace.holdouts_func = check_all_holdout_tasks_trace;
--
2.40.1