Hi Thomas,
At 03/09/2018 11:08 PM, Thomas Gleixner wrote:
[...]
I'm not sure if there is a clear indicator whether physcial hotplug is
supported or not, but the ACPI folks (x86) and architecture maintainers
+cc Rafael
should be able to answer that question. I have a machine which says:
smpboot: Allowing 128 CPUs, 96 hotplug CPUs
There is definitely no way to hotplug anything on that machine and sure the
AFAIK, in ACPI based dynamic reconfiguration, there is no clear
indicator. In theory, If the ACPI tables have the hotpluggable
CPU resources, the OS can support physical hotplug.
For your machine, Did your CPUs support multi-threading, but not enable
it?
And, sometimes we should not trust the number of possible CPUs. I also
met the situation that BIOS told to ACPI that it could support physical
CPUs hotplug, But actually, there was no hardware slots in the machine.
the ACPI tables like user inputs which should be validated when we use.
existing spread algorithm will waste vectors to no end.
Sure then there is virt, which can pretend to have a gazillion of possible
hotpluggable CPUs, but virt is an insanity on its own. Though someone might
come up with reasonable heuristics for that as well.
Thoughts?
Do we have to map the vectors to CPU statically? Can we map them when
we hotplug/enable the possible CPU?
Thanks,
dou
