rcu: Remove TINY_RCU bloat from pointless boot parameters
The rcu_expedited, rcu_normal, and rcu_normal_after_boot kernel boot
parameters are pointless in the case of TINY_RCU because in that case
synchronous grace periods, both expedited and normal, are no-ops.
However, these three symbols contribute several hundred bytes of bloat.
This commit therefore uses CPP directives to avoid compiling this code
in TINY_RCU kernels.
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 197305bb..d8186da 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -3308,20 +3308,23 @@
of synchronize_rcu(). This reduces latency,
but can increase CPU utilization, degrade
real-time latency, and degrade energy efficiency.
+ No effect on CONFIG_TINY_RCU kernels.
rcupdate.rcu_normal= [KNL]
Use only normal grace-period primitives,
for example, synchronize_rcu() instead of
synchronize_rcu_expedited(). This improves
- real-time latency, CPU utilization, and energy
- efficiency, but can expose users to increased
- grace-period latency. This parameter overrides
- rcupdate.rcu_expedited.
+ real-time latency, CPU utilization, and
+ energy efficiency, but can expose users to
+ increased grace-period latency. This parameter
+ overrides rcupdate.rcu_expedited. No effect on
+ CONFIG_TINY_RCU kernels.
rcupdate.rcu_normal_after_boot= [KNL]
Once boot has completed (that is, after
rcu_end_inkernel_boot() has been invoked), use
- only normal grace-period primitives.
+ only normal grace-period primitives. No effect
+ on CONFIG_TINY_RCU kernels.
rcupdate.rcu_task_stall_timeout= [KNL]
Set timeout in jiffies for RCU task stall warning