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Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

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Pull RCU updates from Ingo Molnar:
 "The sole purpose of these changes is to shrink and simplify the RCU
  code base, which has suffered from creeping bloat over the past couple
  of years. The end result is a net removal of ~2700 lines of code:

     79 files changed, 1496 insertions(+), 4211 deletions(-)

  Plus there's a marked reduction in the Kconfig space complexity as
  well, here's the number of matches on 'grep RCU' in the .config:

                               before       after

     x86-defconfig                 17          15
     x86-allmodconfig              33          20"

* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (86 commits)
  rcu: Remove RCU CPU stall warnings from Tiny RCU
  rcu: Remove event tracing from Tiny RCU
  rcu: Move RCU debug Kconfig options to kernel/rcu
  rcu: Move RCU non-debug Kconfig options to kernel/rcu
  rcu: Eliminate NOCBs CPU-state Kconfig options
  rcu: Remove debugfs tracing
  srcu: Remove Classic SRCU
  srcu: Fix rcutorture-statistics typo
  rcu: Remove SPARSE_RCU_POINTER Kconfig option
  rcu: Remove the now-obsolete PROVE_RCU_REPEATEDLY Kconfig option
  rcu: Remove typecheck() from RCU locking wrapper functions
  rcu: Remove #ifdef moving rcu_end_inkernel_boot from rcupdate.h
  rcu: Remove nohz_full full-system-idle state machine
  rcu: Remove the RCU_KTHREAD_PRIO Kconfig option
  rcu: Remove *_SLOW_* Kconfig options
  srcu: Use rnp->lock wrappers to replace explicit memory barriers
  rcu: Move rnp->lock wrappers for SRCU use
  rcu: Convert rnp->lock wrappers to macros for SRCU use
  rcu: Refactor #includes from include/linux/rcupdate.h
  bcm47xx: Fix build regression
  ...
This commit is contained in:
Linus Torvalds
2017-07-03 11:34:53 -07:00
parent e94693f797 567b64aaef
commit 330e9e4625
79 changed files with 1497 additions and 4212 deletions
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50
kernel/time/Kconfig
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@@ -126,56 +126,6 @@ config NO_HZ_FULL_ALL
Note the boot CPU will still be kept outside the range to
handle the timekeeping duty.
config NO_HZ_FULL_SYSIDLE
bool "Detect full-system idle state for full dynticks system"
depends on NO_HZ_FULL
default n
help
At least one CPU must keep the scheduling-clock tick running for
timekeeping purposes whenever there is a non-idle CPU, where
"non-idle" also includes dynticks CPUs as long as they are
running non-idle tasks. Because the underlying adaptive-tick
support cannot distinguish between all CPUs being idle and
all CPUs each running a single task in dynticks mode, the
underlying support simply ensures that there is always a CPU
handling the scheduling-clock tick, whether or not all CPUs
are idle. This Kconfig option enables scalable detection of
the all-CPUs-idle state, thus allowing the scheduling-clock
tick to be disabled when all CPUs are idle. Note that scalable
detection of the all-CPUs-idle state means that larger systems
will be slower to declare the all-CPUs-idle state.
Say Y if you would like to help debug all-CPUs-idle detection.
Say N if you are unsure.
config NO_HZ_FULL_SYSIDLE_SMALL
int "Number of CPUs above which large-system approach is used"
depends on NO_HZ_FULL_SYSIDLE
range 1 NR_CPUS
default 8
help
The full-system idle detection mechanism takes a lazy approach
on large systems, as is required to attain decent scalability.
However, on smaller systems, scalability is not anywhere near as
large a concern as is energy efficiency. The sysidle subsystem
therefore uses a fast but non-scalable algorithm for small
systems and a lazier but scalable algorithm for large systems.
This Kconfig parameter defines the number of CPUs in the largest
system that will be considered to be "small".
The default value will be fine in most cases. Battery-powered
systems that (1) enable NO_HZ_FULL_SYSIDLE, (2) have larger
numbers of CPUs, and (3) are suffering from battery-lifetime
problems due to long sysidle latencies might wish to experiment
with larger values for this Kconfig parameter. On the other
hand, they might be even better served by disabling NO_HZ_FULL
entirely, given that NO_HZ_FULL is intended for HPC and
real-time workloads that at present do not tend to be run on
battery-powered systems.
Take the default if you are unsure.
config NO_HZ
bool "Old Idle dynticks config"
depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS