diff options
Diffstat (limited to 'init/Kconfig')
| -rw-r--r-- | init/Kconfig | 86 |
1 files changed, 83 insertions, 3 deletions
diff --git a/init/Kconfig b/init/Kconfig index 8e9904fc302..f6281711166 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -945,10 +945,90 @@ source "block/Kconfig" config PREEMPT_NOTIFIERS bool +choice + prompt "RCU Implementation" + default CLASSIC_RCU + config CLASSIC_RCU - def_bool !PREEMPT_RCU + bool "Classic RCU" help This option selects the classic RCU implementation that is designed for best read-side performance on non-realtime - systems. Classic RCU is the default. Note that the - PREEMPT_RCU symbol is used to select/deselect this option. + 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. + +config PREEMPT_RCU + bool "Preemptible 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. + +endchoice + +config RCU_TRACE + bool "Enable tracing for RCU" + depends on TREE_RCU || PREEMPT_RCU + help + This option provides tracing in RCU which presents stats + in debugfs for debugging RCU implementation. + + Say Y here if you want to enable RCU tracing + Say N if you are unsure. + +config RCU_FANOUT + int "Tree-based hierarchical RCU fanout value" + range 2 64 if 64BIT + range 2 32 if !64BIT + depends on TREE_RCU + default 64 if 64BIT + default 32 if !64BIT + help + This option controls the fanout of hierarchical implementations + of RCU, allowing RCU to work efficiently on machines with + large numbers of CPUs. This value must be at least the cube + root of NR_CPUS, which allows NR_CPUS up to 32,768 for 32-bit + systems and up to 262,144 for 64-bit systems. + + Select a specific number if testing RCU itself. + Take the default if unsure. + +config RCU_FANOUT_EXACT + bool "Disable tree-based hierarchical RCU auto-balancing" + depends on TREE_RCU + default n + help + This option forces use of the exact RCU_FANOUT value specified, + regardless of imbalances in the hierarchy. This is useful for + testing RCU itself, and might one day be useful on systems with + strong NUMA behavior. + + Without RCU_FANOUT_EXACT, the code will balance the hierarchy. + + 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 + select DEBUG_FS + help + This option provides tracing for the PREEMPT_RCU implementation, + permitting Makefile to trivially select kernel/rcupreempt_trace.c. |