linux_dsm_epyc7002/include
Thomas Gleixner 05736e4ac1 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>
2018-06-21 14:20:58 +02:00
..
acpi Additional ACPI updates for 4.18-rc1 2018-06-13 07:32:10 -07:00
asm-generic x86/speculation/l1tf: Disallow non privileged high MMIO PROT_NONE mappings 2018-06-20 19:10:01 +02:00
clocksource
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2018-06-05 15:51:21 -07:00
drm drm for v4.18-rc1 2018-06-06 08:16:33 -07:00
dt-bindings ARM: SoC driver updates 2018-06-11 18:15:22 -07:00
keys docs: Fix some broken references 2018-06-15 18:10:01 -03:00
kvm
linux cpu/hotplug: Provide knobs to control SMT 2018-06-21 14:20:58 +02:00
math-emu
media
memory
misc
net sctp: define sctp_packet_gso_append to build GSO frames 2018-06-14 10:25:53 -07:00
pcmcia
ras
rdma Convert infiniband uverbs to struct_size 2018-06-12 16:19:22 -07:00
scsi SCSI misc on 20180610 2018-06-10 13:01:12 -07:00
soc ARM: SoC: late updates 2018-06-11 18:19:45 -07:00
sound sound updates for 4.18 2018-06-06 09:08:38 -07:00
target
trace NFS client updates for Linux 4.18 2018-06-12 10:09:03 -07:00
uapi Solve a series of broken links for files under Documentation: 2018-06-17 05:25:18 +09:00
video fbdev changes for v4.18: 2018-06-17 05:00:24 +09:00
xen docs: Fix some broken references 2018-06-15 18:10:01 -03:00