diff options
Diffstat (limited to 'init')
| -rw-r--r-- | init/Kconfig | 46 | ||||
| -rw-r--r-- | init/main.c | 2 |
2 files changed, 16 insertions, 32 deletions
diff --git a/init/Kconfig b/init/Kconfig index 3f7e60995c8..8e8b76d8a27 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -316,38 +316,28 @@ choice prompt "RCU Implementation" default TREE_RCU -config CLASSIC_RCU - bool "Classic RCU" - help - This option selects the classic RCU implementation that is - designed for best read-side performance on non-realtime - systems. - - Select this option if you are unsure. - config TREE_RCU bool "Tree-based hierarchical RCU" help This option selects the RCU implementation that is designed for very large SMP system with hundreds or - thousands of CPUs. + thousands of CPUs. It also scales down nicely to + smaller systems. -config PREEMPT_RCU - bool "Preemptible RCU" +config TREE_PREEMPT_RCU + bool "Preemptable tree-based hierarchical RCU" depends on PREEMPT help - This option reduces the latency of the kernel by making certain - RCU sections preemptible. Normally RCU code is non-preemptible, if - this option is selected then read-only RCU sections become - preemptible. This helps latency, but may expose bugs due to - now-naive assumptions about each RCU read-side critical section - remaining on a given CPU through its execution. + This option selects the RCU implementation that is + designed for very large SMP systems with hundreds or + thousands of CPUs, but for which real-time response + is also required. endchoice config RCU_TRACE bool "Enable tracing for RCU" - depends on TREE_RCU || PREEMPT_RCU + depends on TREE_RCU || TREE_PREEMPT_RCU help This option provides tracing in RCU which presents stats in debugfs for debugging RCU implementation. @@ -359,7 +349,7 @@ config RCU_FANOUT int "Tree-based hierarchical RCU fanout value" range 2 64 if 64BIT range 2 32 if !64BIT - depends on TREE_RCU + depends on TREE_RCU || TREE_PREEMPT_RCU default 64 if 64BIT default 32 if !64BIT help @@ -374,7 +364,7 @@ config RCU_FANOUT config RCU_FANOUT_EXACT bool "Disable tree-based hierarchical RCU auto-balancing" - depends on TREE_RCU + depends on TREE_RCU || TREE_PREEMPT_RCU default n help This option forces use of the exact RCU_FANOUT value specified, @@ -387,18 +377,12 @@ config RCU_FANOUT_EXACT Say N if unsure. config TREE_RCU_TRACE - def_bool RCU_TRACE && TREE_RCU - select DEBUG_FS - help - This option provides tracing for the TREE_RCU implementation, - permitting Makefile to trivially select kernel/rcutree_trace.c. - -config PREEMPT_RCU_TRACE - def_bool RCU_TRACE && PREEMPT_RCU + def_bool RCU_TRACE && ( TREE_RCU || TREE_PREEMPT_RCU ) select DEBUG_FS help - This option provides tracing for the PREEMPT_RCU implementation, - permitting Makefile to trivially select kernel/rcupreempt_trace.c. + This option provides tracing for the TREE_RCU and + TREE_PREEMPT_RCU implementations, permitting Makefile to + trivially select kernel/rcutree_trace.c. endmenu # "RCU Subsystem" diff --git a/init/main.c b/init/main.c index 11f4f145be3..525f6fb2bd2 100644 --- a/init/main.c +++ b/init/main.c @@ -451,6 +451,7 @@ static noinline void __init_refok rest_init(void) { int pid; + rcu_scheduler_starting(); kernel_thread(kernel_init, NULL, CLONE_FS | CLONE_SIGHAND); numa_default_policy(); pid = kernel_thread(kthreadd, NULL, CLONE_FS | CLONE_FILES); @@ -462,7 +463,6 @@ static noinline void __init_refok rest_init(void) * at least once to get things moving: */ init_idle_bootup_task(current); - rcu_scheduler_starting(); preempt_enable_no_resched(); schedule(); preempt_disable(); |