diff options
Diffstat (limited to 'init')
| -rw-r--r-- | init/Kconfig | 52 |
1 files changed, 45 insertions, 7 deletions
diff --git a/init/Kconfig b/init/Kconfig index 9d76b99af1b9..a291b7ef4738 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -505,7 +505,7 @@ config PREEMPT_RCU def_bool TREE_PREEMPT_RCU help This option enables preemptible-RCU code that is common between - the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations. + TREE_PREEMPT_RCU and, in the old days, TINY_PREEMPT_RCU. config RCU_STALL_COMMON def_bool ( TREE_RCU || TREE_PREEMPT_RCU || RCU_TRACE ) @@ -737,7 +737,7 @@ choice config RCU_NOCB_CPU_NONE bool "No build_forced no-CBs CPUs" - depends on RCU_NOCB_CPU && !NO_HZ_FULL + depends on RCU_NOCB_CPU && !NO_HZ_FULL_ALL help This option does not force any of the CPUs to be no-CBs CPUs. Only CPUs designated by the rcu_nocbs= boot parameter will be @@ -751,7 +751,7 @@ config RCU_NOCB_CPU_NONE config RCU_NOCB_CPU_ZERO bool "CPU 0 is a build_forced no-CBs CPU" - depends on RCU_NOCB_CPU && !NO_HZ_FULL + depends on RCU_NOCB_CPU && !NO_HZ_FULL_ALL help This option forces CPU 0 to be a no-CBs CPU, so that its RCU callbacks are invoked by a per-CPU kthread whose name begins @@ -807,15 +807,53 @@ config LOG_BUF_SHIFT range 12 21 default 17 help - Select kernel log buffer size as a power of 2. + Select the minimal kernel log buffer size as a power of 2. + The final size is affected by LOG_CPU_MAX_BUF_SHIFT config + parameter, see below. Any higher size also might be forced + by "log_buf_len" boot parameter. + Examples: - 17 => 128 KB + 17 => 128 KB 16 => 64 KB - 15 => 32 KB - 14 => 16 KB + 15 => 32 KB + 14 => 16 KB 13 => 8 KB 12 => 4 KB +config LOG_CPU_MAX_BUF_SHIFT + int "CPU kernel log buffer size contribution (13 => 8 KB, 17 => 128KB)" + range 0 21 + default 12 if !BASE_SMALL + default 0 if BASE_SMALL + help + This option allows to increase the default ring buffer size + according to the number of CPUs. The value defines the contribution + of each CPU as a power of 2. The used space is typically only few + lines however it might be much more when problems are reported, + e.g. backtraces. + + The increased size means that a new buffer has to be allocated and + the original static one is unused. It makes sense only on systems + with more CPUs. Therefore this value is used only when the sum of + contributions is greater than the half of the default kernel ring + buffer as defined by LOG_BUF_SHIFT. The default values are set + so that more than 64 CPUs are needed to trigger the allocation. + + Also this option is ignored when "log_buf_len" kernel parameter is + used as it forces an exact (power of two) size of the ring buffer. + + The number of possible CPUs is used for this computation ignoring + hotplugging making the compuation optimal for the the worst case + scenerio while allowing a simple algorithm to be used from bootup. + + Examples shift values and their meaning: + 17 => 128 KB for each CPU + 16 => 64 KB for each CPU + 15 => 32 KB for each CPU + 14 => 16 KB for each CPU + 13 => 8 KB for each CPU + 12 => 4 KB for each CPU + # # Architectures with an unreliable sched_clock() should select this: # |