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| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2015-11-25 18:56:00 -0800 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2015-12-04 12:26:54 -0800 |
| commit | 3e42ec1aa716f10c68294b8492ae3ea684528699 (patch) | |
| tree | be431b624157914bd08d965fed9423fe267ff927 | |
| parent | 967dcb8fe6a9a75be346400539261e0416baf370 (diff) | |
rcu: Allow expedited grace periods to be disabled at init
Expedited grace periods can speed up boot, but are undesirable in
aggressive real-time systems. This commit therefore introduces a
kernel parameter rcupdate.rcu_normal_after_boot that disables
expedited grace periods just before init is spawned.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
| -rw-r--r-- | Documentation/kernel-parameters.txt | 5 | ||||
| -rw-r--r-- | kernel/rcu/update.c | 5 |
2 files changed, 10 insertions, 0 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 7673943d3085..197305bbb9b7 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -3318,6 +3318,11 @@ bytes respectively. Such letter suffixes can also be entirely omitted. grace-period latency. This parameter overrides rcupdate.rcu_expedited. + 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. + rcupdate.rcu_task_stall_timeout= [KNL] Set timeout in jiffies for RCU task stall warning messages. Disable with a value less than or equal diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c index 8fccda3a794d..12b91f5a60a6 100644 --- a/kernel/rcu/update.c +++ b/kernel/rcu/update.c @@ -63,6 +63,9 @@ MODULE_ALIAS("rcupdate"); module_param(rcu_expedited, int, 0); module_param(rcu_normal, int, 0); +static int rcu_normal_after_boot; +module_param(rcu_normal_after_boot, int, 0); + #if defined(CONFIG_DEBUG_LOCK_ALLOC) && defined(CONFIG_PREEMPT_COUNT) /** * rcu_read_lock_sched_held() - might we be in RCU-sched read-side critical section? @@ -178,6 +181,8 @@ void rcu_end_inkernel_boot(void) { if (IS_ENABLED(CONFIG_RCU_EXPEDITE_BOOT)) rcu_unexpedite_gp(); + if (rcu_normal_after_boot) + WRITE_ONCE(rcu_normal, 1); } #ifdef CONFIG_PREEMPT_RCU |