Le 27/06/2017 16:21, Thomas Gleixner a écrit :
> On Tue, 27 Jun 2017, Suravee Suthikulpanit wrote:
>> On 6/27/17 17:48, Borislav Petkov wrote:
>>> On Tue, Jun 27, 2017 at 01:40:52AM -0500, Suravee Suthikulpanit wrote:
>>>> However, this is not the case on AMD family17h multi-die processor
>>>> platforms, which can have up to 4 dies per socket as shown in the
>>>> following system topology.
>>> So what exactly does that mean? A die is a package on ZN and you can have up
>>> to 4 packages on a physical socket?
>> Yes. 4 packages (or 4 dies, or 4 NUMA nodes) in a socket.
> And why is this relevant at all?
>
> The kernel does not care about sockets. Sockets are electromechanical
> components and completely irrelevant.
>
> The kernel cares about :
>
> Threads - Single scheduling unit
>
> Cores - Contains one or more threads
>
> Packages - Contains one or more cores. The cores share L3.
>
> NUMA Node - Contains one or more Packages which share a memory
> controller.
>
> I'm not aware of x86 systems which have several Packages
> sharing a memory controller, so Package == NUMA Node
> (but I might be wrong here).
You often have multiple NUMA nodes inside a single package. That's what
we see in sysfs on Intel (since haswell, when Cluster-on-Die is enabled)
and on AMD (since magny-cours).
Kernel "packages" contains cores whose "physical_package_id" are the
same. Documentation says:
physical_package_id: physical package id of cpu#. Typically
corresponds to a physical socket number, but the actual value
is architecture and platform dependent.
I don't know if it's possible on x86 to have different
physical_package_ids for different cores on a single socket.
Brice
