Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler fixes from Thomas Gleixner:
"Three patches addressing the fallout of the CPU_ISOLATION changes
especially with NO_HZ_FULL plus documentation of boot parameter
dependency"
* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/isolation: Document boot parameters dependency on CONFIG_CPU_ISOLATION=y
sched/isolation: Enable CONFIG_CPU_ISOLATION=y by default
sched/isolation: Make CONFIG_NO_HZ_FULL select CONFIG_CPU_ISOLATION
diff --git a/Documentation/admin-guide/kernel-parameters.rst b/Documentation/admin-guide/kernel-parameters.rst
index b2598cc..7242cbd 100644
--- a/Documentation/admin-guide/kernel-parameters.rst
+++ b/Documentation/admin-guide/kernel-parameters.rst
@@ -109,6 +109,7 @@
IPV6 IPv6 support is enabled.
ISAPNP ISA PnP code is enabled.
ISDN Appropriate ISDN support is enabled.
+ ISOL CPU Isolation is enabled.
JOY Appropriate joystick support is enabled.
KGDB Kernel debugger support is enabled.
KVM Kernel Virtual Machine support is enabled.
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index e49311d..7041c67 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -1737,7 +1737,7 @@
isapnp= [ISAPNP]
Format: <RDP>,<reset>,<pci_scan>,<verbosity>
- isolcpus= [KNL,SMP] Isolate a given set of CPUs from disturbance.
+ isolcpus= [KNL,SMP,ISOL] Isolate a given set of CPUs from disturbance.
[Deprecated - use cpusets instead]
Format: [flag-list,]<cpu-list>
@@ -2662,7 +2662,7 @@
Valid arguments: on, off
Default: on
- nohz_full= [KNL,BOOT]
+ nohz_full= [KNL,BOOT,SMP,ISOL]
The argument is a cpu list, as described above.
In kernels built with CONFIG_NO_HZ_FULL=y, set
the specified list of CPUs whose tick will be stopped
diff --git a/init/Kconfig b/init/Kconfig
index 2934249..690a381 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -461,10 +461,14 @@
config CPU_ISOLATION
bool "CPU isolation"
+ default y
help
Make sure that CPUs running critical tasks are not disturbed by
any source of "noise" such as unbound workqueues, timers, kthreads...
- Unbound jobs get offloaded to housekeeping CPUs.
+ Unbound jobs get offloaded to housekeeping CPUs. This is driven by
+ the "isolcpus=" boot parameter.
+
+ Say Y if unsure.
source "kernel/rcu/Kconfig"
diff --git a/kernel/time/Kconfig b/kernel/time/Kconfig
index e776fc8..f6b5f19 100644
--- a/kernel/time/Kconfig
+++ b/kernel/time/Kconfig
@@ -95,6 +95,7 @@
select RCU_NOCB_CPU
select VIRT_CPU_ACCOUNTING_GEN
select IRQ_WORK
+ select CPU_ISOLATION
help
Adaptively try to shutdown the tick whenever possible, even when
the CPU is running tasks. Typically this requires running a single
