diff options
Diffstat (limited to 'init')
| -rw-r--r-- | init/Kconfig | 50 | ||||
| -rw-r--r-- | init/do_mounts.c | 2 | ||||
| -rw-r--r-- | init/main.c | 7 |
3 files changed, 51 insertions, 8 deletions
diff --git a/init/Kconfig b/init/Kconfig index 6cfd71d0646..6d18ef8071b 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -458,6 +458,33 @@ config RCU_FANOUT Select a specific number if testing RCU itself. Take the default if unsure. +config RCU_FANOUT_LEAF + int "Tree-based hierarchical RCU leaf-level fanout value" + range 2 RCU_FANOUT if 64BIT + range 2 RCU_FANOUT if !64BIT + depends on TREE_RCU || TREE_PREEMPT_RCU + default 16 + help + This option controls the leaf-level fanout of hierarchical + implementations of RCU, and allows trading off cache misses + against lock contention. Systems that synchronize their + scheduling-clock interrupts for energy-efficiency reasons will + want the default because the smaller leaf-level fanout keeps + lock contention levels acceptably low. Very large systems + (hundreds or thousands of CPUs) will instead want to set this + value to the maximum value possible in order to reduce the + number of cache misses incurred during RCU's grace-period + initialization. These systems tend to run CPU-bound, and thus + are not helped by synchronized interrupts, and thus tend to + skew them, which reduces lock contention enough that large + leaf-level fanouts work well. + + Select a specific number if testing RCU itself. + + Select the maximum permissible value for large systems. + + Take the default if unsure. + config RCU_FANOUT_EXACT bool "Disable tree-based hierarchical RCU auto-balancing" depends on TREE_RCU || TREE_PREEMPT_RCU @@ -515,10 +542,25 @@ config RCU_BOOST_PRIO depends on RCU_BOOST default 1 help - This option specifies the real-time priority to which preempted - RCU readers are to be boosted. If you are working with CPU-bound - real-time applications, you should specify a priority higher then - the highest-priority CPU-bound application. + This option specifies the real-time priority to which long-term + preempted RCU readers are to be boosted. If you are working + with a real-time application that has one or more CPU-bound + threads running at a real-time priority level, you should set + RCU_BOOST_PRIO to a priority higher then the highest-priority + real-time CPU-bound thread. The default RCU_BOOST_PRIO value + of 1 is appropriate in the common case, which is real-time + applications that do not have any CPU-bound threads. + + Some real-time applications might not have a single real-time + thread that saturates a given CPU, but instead might have + multiple real-time threads that, taken together, fully utilize + that CPU. In this case, you should set RCU_BOOST_PRIO to + a priority higher than the lowest-priority thread that is + conspiring to prevent the CPU from running any non-real-time + tasks. For example, if one thread at priority 10 and another + thread at priority 5 are between themselves fully consuming + the CPU time on a given CPU, then RCU_BOOST_PRIO should be + set to priority 6 or higher. Specify the real-time priority, or take the default if unsure. diff --git a/init/do_mounts.c b/init/do_mounts.c index 0e93f92a034..42b0707c348 100644 --- a/init/do_mounts.c +++ b/init/do_mounts.c @@ -472,7 +472,7 @@ void __init change_floppy(char *fmt, ...) void __init mount_root(void) { #ifdef CONFIG_ROOT_NFS - if (MAJOR(ROOT_DEV) == UNNAMED_MAJOR) { + if (ROOT_DEV == Root_NFS) { if (mount_nfs_root()) return; diff --git a/init/main.c b/init/main.c index 44b2433334c..cb54cd3dbf0 100644 --- a/init/main.c +++ b/init/main.c @@ -560,9 +560,6 @@ asmlinkage void __init start_kernel(void) early_boot_irqs_disabled = false; local_irq_enable(); - /* Interrupts are enabled now so all GFP allocations are safe. */ - gfp_allowed_mask = __GFP_BITS_MASK; - kmem_cache_init_late(); /* @@ -842,6 +839,10 @@ static int __init kernel_init(void * unused) * Wait until kthreadd is all set-up. */ wait_for_completion(&kthreadd_done); + + /* Now the scheduler is fully set up and can do blocking allocations */ + gfp_allowed_mask = __GFP_BITS_MASK; + /* * init can allocate pages on any node */ |