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authorLinus Torvalds <torvalds@linux-foundation.org>2013-09-04 09:36:54 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-09-04 09:36:54 -0700
commit6832d9652f395f7d13003e3884942c40f52ac1fa (patch)
tree40555ad5eda9700cb973dac4db136ad97f5e8b19 /init
parent228abe73ad67665d71eacd6a8a347dd76b0115ae (diff)
parentc2e7fcf53c3cb02b4ada1c66a9bc8a4d97d58aba (diff)
downloadlinux-6832d9652f395f7d13003e3884942c40f52ac1fa.tar.gz
Merge branch 'timers-nohz-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timers/nohz changes from Ingo Molnar: "It mostly contains fixes and full dynticks off-case optimizations, by Frederic Weisbecker" * 'timers-nohz-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (24 commits) nohz: Include local CPU in full dynticks global kick nohz: Optimize full dynticks's sched hooks with static keys nohz: Optimize full dynticks state checks with static keys nohz: Rename a few state variables vtime: Always debug check snapshot source _before_ updating it vtime: Always scale generic vtime accounting results vtime: Optimize full dynticks accounting off case with static keys vtime: Describe overriden functions in dedicated arch headers m68k: hardirq_count() only need preempt_mask.h hardirq: Split preempt count mask definitions context_tracking: Split low level state headers vtime: Fix racy cputime delta update vtime: Remove a few unneeded generic vtime state checks context_tracking: User/kernel broundary cross trace events context_tracking: Optimize context switch off case with static keys context_tracking: Optimize guest APIs off case with static key context_tracking: Optimize main APIs off case with static key context_tracking: Ground setup for static key use context_tracking: Remove full dynticks' hacky dependency on wide context tracking nohz: Only enable context tracking on full dynticks CPUs ...
Diffstat (limited to 'init')
-rw-r--r--init/Kconfig28
-rw-r--r--init/main.c2
2 files changed, 24 insertions, 6 deletions
diff --git a/init/Kconfig b/init/Kconfig
index cc917d3ec85..0a2c4bcf179 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -528,13 +528,29 @@ config RCU_USER_QS
config CONTEXT_TRACKING_FORCE
bool "Force context tracking"
depends on CONTEXT_TRACKING
- default CONTEXT_TRACKING
+ default y if !NO_HZ_FULL
help
- Probe on user/kernel boundaries by default in order to
- test the features that rely on it such as userspace RCU extended
- quiescent states.
- This test is there for debugging until we have a real user like the
- full dynticks mode.
+ The major pre-requirement for full dynticks to work is to
+ support the context tracking subsystem. But there are also
+ other dependencies to provide in order to make the full
+ dynticks working.
+
+ This option stands for testing when an arch implements the
+ context tracking backend but doesn't yet fullfill all the
+ requirements to make the full dynticks feature working.
+ Without the full dynticks, there is no way to test the support
+ for context tracking and the subsystems that rely on it: RCU
+ userspace extended quiescent state and tickless cputime
+ accounting. This option copes with the absence of the full
+ dynticks subsystem by forcing the context tracking on all
+ CPUs in the system.
+
+ Say Y only if you're working on the developpement of an
+ architecture backend for the context tracking.
+
+ Say N otherwise, this option brings an overhead that you
+ don't want in production.
+
config RCU_FANOUT
int "Tree-based hierarchical RCU fanout value"
diff --git a/init/main.c b/init/main.c
index d03d2ec2eac..af310afbef2 100644
--- a/init/main.c
+++ b/init/main.c
@@ -75,6 +75,7 @@
#include <linux/blkdev.h>
#include <linux/elevator.h>
#include <linux/sched_clock.h>
+#include <linux/context_tracking.h>
#include <asm/io.h>
#include <asm/bugs.h>
@@ -545,6 +546,7 @@ asmlinkage void __init start_kernel(void)
idr_init_cache();
rcu_init();
tick_nohz_init();
+ context_tracking_init();
radix_tree_init();
/* init some links before init_ISA_irqs() */
early_irq_init();