forked from Minki/linux
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>
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@ -3318,6 +3318,11 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
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grace-period latency. This parameter overrides
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rcupdate.rcu_expedited.
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rcupdate.rcu_normal_after_boot= [KNL]
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Once boot has completed (that is, after
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rcu_end_inkernel_boot() has been invoked), use
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only normal grace-period primitives.
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rcupdate.rcu_task_stall_timeout= [KNL]
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Set timeout in jiffies for RCU task stall warning
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messages. Disable with a value less than or equal
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@ -63,6 +63,9 @@ MODULE_ALIAS("rcupdate");
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module_param(rcu_expedited, int, 0);
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module_param(rcu_normal, int, 0);
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static int rcu_normal_after_boot;
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module_param(rcu_normal_after_boot, int, 0);
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#if defined(CONFIG_DEBUG_LOCK_ALLOC) && defined(CONFIG_PREEMPT_COUNT)
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/**
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* rcu_read_lock_sched_held() - might we be in RCU-sched read-side critical section?
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@ -178,6 +181,8 @@ void rcu_end_inkernel_boot(void)
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{
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if (IS_ENABLED(CONFIG_RCU_EXPEDITE_BOOT))
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rcu_unexpedite_gp();
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if (rcu_normal_after_boot)
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WRITE_ONCE(rcu_normal, 1);
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}
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#ifdef CONFIG_PREEMPT_RCU
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