Re: [PATCH 2/2 v6] mm/mempolicy: Don't create weight sysfs for memoryless nodes

[Honggyu Kim]

On 3/18/2025 5:02 PM, Yunjeong Mun wrote:
> Hi Gregory, I have one more question below.
>
> On Tue, 11 Mar 2025 00:42:49 -0400 Gregory Price <gourry@xxxxxxxxxx> wrote:
> > On Tue, Mar 11, 2025 at 01:02:07PM +0900, Yunjeong Mun wrote:
> >
> > forenote - Hi Andrew, please hold off on the auto-configuration patch
> > for now, the sk group has identified a hotplug issue we need to work out
> > and we'll likely need to merge these two patch set together.  I really
> > appreciate your patience with this feature.
> >
> > > Hi Gregory,
> > >
> > > In my understanding, the reason we are seeing 12 NUMA node is because
> > > it loops through node_states[N_POSSIBLE] and its value is 4095 (twelves ones)
> > > in the code [1]  below:
> > ... snip ...
> >
> > Appreciated, so yes this confirms what i thought was going on.  There's
> > 4 host bridges, 2 devices on each host bridge, and an extra CFMWS per
> > socket that is intended to interleave across the host bridges.
>
> Thanks for confirm. Honggyu represented it as a tree sturcture:
> rootport/
> ├── socket0
> │   ├── cross-host-bridge0 -> SRAT && CEDT (interleave on) --> NODE 2
> │   │   ├── host-bridge0 -> CEDT
> │   │   │   ├── cxl0 -> CEDT
> │   │   │   └── cxl1-> CEDT
> │   │   └── host-bridge1 -> CEDT
> │   │       ├── cxl2 -> CEDT
> │   │       └── cxl3 -> CEDT
> │   └── dram0 -> SRAT ---------------------------------------> NODE 0
> └── socket1
>      ├── cross-host-bridge1 -> SRAT && CEDT (interleave on)---> NODE 3
>      │   ├── host-bridge2 -> CEDT
>      │   │   ├── cxl4 -> CEDT
>      │   │   └── cxl5 -> CEDT
>      │   └── host-bridge3 -> CEDT
>      │       ├── cxl6 -> CEDT
>      │       └── cxl7 -> CEDT
>      └── dram1 -> SRAT ---------------------------------------> NODE 1

Some simple corrections here.  host-bridge{0-3} above aren't detected from CEDT.
The corrected structure is as follows.

rootport/
├── socket0
│   ├── cross-host-bridge0 -> SRAT && CEDT (interleave on) --> NODE 2
│   │   ├── host-bridge0
│   │   │   ├── cxl0 -> CEDT
│   │   │   └── cxl1-> CEDT
│   │   └── host-bridge1
│   │       ├── cxl2 -> CEDT
│   │       └── cxl3 -> CEDT
│   └── dram0 -> SRAT ---------------------------------------> NODE 0
└── socket1
     ├── cross-host-bridge1 -> SRAT && CEDT (interleave on)---> NODE 3
     │   ├── host-bridge2
     │   │   ├── cxl4 -> CEDT
     │   │   └── cxl5 -> CEDT
     │   └── host-bridge3
     │       ├── cxl6 -> CEDT
     │       └── cxl7 -> CEDT
     └── dram1 -> SRAT ---------------------------------------> NODE 1

Thanks,
Honggyu