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authorThomas Gleixner <tglx@linutronix.de>2018-05-29 17:48:27 +0200
committerThomas Gleixner <tglx@linutronix.de>2018-06-21 14:20:58 +0200
commit05736e4ac13c08a4a9b1ef2de26dd31a32cbee57 (patch)
treedbd83041b6208c02967f398cbf32f8cfd1b83db7 /arch/Kconfig
parentcpu/hotplug: Split do_cpu_down() (diff)
downloadlinux-dev-05736e4ac13c08a4a9b1ef2de26dd31a32cbee57.tar.xz
linux-dev-05736e4ac13c08a4a9b1ef2de26dd31a32cbee57.zip
cpu/hotplug: Provide knobs to control SMT
Provide a command line and a sysfs knob to control SMT. The command line options are: 'nosmt': Enumerate secondary threads, but do not online them 'nosmt=force': Ignore secondary threads completely during enumeration via MP table and ACPI/MADT. The sysfs control file has the following states (read/write): 'on': SMT is enabled. Secondary threads can be freely onlined 'off': SMT is disabled. Secondary threads, even if enumerated cannot be onlined 'forceoff': SMT is permanentely disabled. Writes to the control file are rejected. 'notsupported': SMT is not supported by the CPU The command line option 'nosmt' sets the sysfs control to 'off'. This can be changed to 'on' to reenable SMT during runtime. The command line option 'nosmt=force' sets the sysfs control to 'forceoff'. This cannot be changed during runtime. When SMT is 'on' and the control file is changed to 'off' then all online secondary threads are offlined and attempts to online a secondary thread later on are rejected. When SMT is 'off' and the control file is changed to 'on' then secondary threads can be onlined again. The 'off' -> 'on' transition does not automatically online the secondary threads. When the control file is set to 'forceoff', the behaviour is the same as setting it to 'off', but the operation is irreversible and later writes to the control file are rejected. When the control status is 'notsupported' then writes to the control file are rejected. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Acked-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to '')
-rw-r--r--arch/Kconfig3
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/Kconfig b/arch/Kconfig
index 1aa59063f1fd..d1f2ed462ac8 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -13,6 +13,9 @@ config KEXEC_CORE
config HAVE_IMA_KEXEC
bool
+config HOTPLUG_SMT
+ bool
+
config OPROFILE
tristate "OProfile system profiling"
depends on PROFILING