Messages in this thread | | | Subject | Re: [PATCH v4] Documentation, dt, numa: Add note to empty NUMA node | From | Gavin Shan <> | Date | Mon, 28 Jun 2021 19:38:11 +1000 |
| |
On 6/28/21 6:34 PM, Andrew Jones wrote: > On Fri, Jun 25, 2021 at 09:14:49PM +1000, Gavin Shan wrote: >> On 6/25/21 8:18 PM, Andrew Jones wrote: >>> On Fri, Jun 25, 2021 at 06:36:48PM +1000, Gavin Shan wrote: >>>> On 6/25/21 5:06 PM, Andrew Jones wrote: >>>>> On Fri, Jun 25, 2021 at 09:02:17AM +0200, Andrew Jones wrote: >>>>>> On Fri, Jun 25, 2021 at 01:23:38PM +0800, Gavin Shan wrote: >>>>>>> The empty memory nodes, where no memory resides in, are allowed. >>>>>>> For these empty memory nodes, the 'len' of 'reg' property is zero. >>>>>>> The NUMA node IDs are still valid and parsed, but memory can be >>>>>>> added to them through hotplug afterwards. I finds difficulty to >>>>>>> get where it's properly documented. >>>>>>> >>>>>>> So lets add note to empty memory nodes in the NUMA binding doc. >>>>>>> >>>>>>> Signed-off-by: Gavin Shan <gshan@redhat.com> >>>>>>> --- >>>>>>> Documentation/devicetree/bindings/numa.txt | 4 ++++ >>>>>>> 1 file changed, 4 insertions(+) >>>>>>> >>>>>>> diff --git a/Documentation/devicetree/bindings/numa.txt b/Documentation/devicetree/bindings/numa.txt >>>>>>> index 21b35053ca5a..0fc882e44270 100644 >>>>>>> --- a/Documentation/devicetree/bindings/numa.txt >>>>>>> +++ b/Documentation/devicetree/bindings/numa.txt >>>>>>> @@ -109,6 +109,10 @@ Example: >>>>>>> Dual socket system consists of 2 boards connected through ccn bus and >>>>>>> each board having one socket/soc of 8 cpus, memory and pci bus. >>>>>>> +Note that empty memory nodes, which no memory resides in, are allowed. >>>>>>> +The NUMA node IDs in these empty memory nodes are still valid, but >>>>>>> +memory can be added into them through hotplug afterwards. >>>>>> >>>>>> Please change the second sentence to: >>>>>> >>>>>> The NUMA node IDs in these empty memory nodes are still valid and >>>>>> memory may be added into them through hotplug afterwards. >>>>>> >>>>>> But, this doesn't look like the right place for this paragraph. You're >>>>>> adding the paragraph to the example section, but the example doesn't have >>>>>> any empty memory nodes. >>>>>> >>>>>> I think the paragraph should be added to section "2 - numa-node-id" and an >>>>> >>>>> Or maybe even create a new section for it. >>>>> >>>>>> example empty memory node should be provided. Also, the commit message >>>>>> talks about the length of 'reg' being zero, which is an important >>>>>> distinction which should also be documented. >>>>>> >>>> >>>> Drew, thanks for your comments. Yeah, it sounds sensible to create >>>> a new section for it and an example would be more helpful. Please >>>> check if below changes are fine to you. I probably need Randy's review >>>> again. >>>> >>>> I'm trying to avoid too many revisions for this sort of trivial patch, >>>> even though I already had. However, it's time frame for v5.14 and I'm >>>> pushing this to be merged during the cycle. >>> >>> We must revise until we're satisfied... Also, I wouldn't call writing >>> specifications trivial. >>> >> >> [...] >> >>> I'll just rewrite it: >>> >>> Empty memory nodes, which no memory resides in, are allowed. The 'length' >>> field of the 'reg' property is zero, but the 'base-address' is a dummy >>> address and invalid. However, the NUMA node IDs and distance maps are >>> still valid and memory may be added into them through hotplug afterwards. >>> >> >> [...] >> >>> >>> You should write how you've selected the dummy addresses for the empty >>> memory nodes, perhaps here in the /* Empty memory node */ comments or >>> above in the paragraph or both. >>> >>>> + memory@0x100000000 { >>>> + device_type = "memory"; >>>> + reg = <0x1 0x0 0x0 0x0>; >>>> + numa-node-id = <2>; >>>> + }; >>>> + >>>> + /* Empty memory node */ >>>> + memory@0x180000000 { >>>> + device_type = "memory"; >>>> + reg = <0x1 0x80000000 0x0 0x0>; >>>> + numa-node-id = <3>; >>>> + }; >>>> + >> >> [...] >> >> Thanks, Drew. As 'base-address' is dummy address and invalid. So we >> would note it as suggestion. With your suggestion integrated, how about >> something like this? >> >> ============================================================================== >> 4 - Empty memory nodes >> ============================================================================== >> >> Empty memory nodes, which no memory resides in, are allowed. The 'length' >> field of the 'reg' property is zero, but the 'base-address' is a dummy >> address and invalid. The 'base-address' could be the summation of highest >> memory address plus the NUMA node ID. However, the NUMA node IDs and >> distance maps are still valid and memory may be added into them through >> hotplug afterwards. >> >> : >> >> memory@0 { >> device_type = "memory"; >> reg = <0x0 0x0 0x0 0x80000000>; >> numa-node-id = <0>; >> }; >> >> memory@0x80000000 { >> device_type = "memory"; >> reg = <0x0 0x80000000 0x0 0x80000000>; >> numa-node-id = <1>; >> }; >> >> /* Empty memory node */ >> memory@0x100000002 { >> device_type = "memory"; >> reg = <0x1 0x2 0x0 0x0>; >> numa-node-id = <2>; >> }; >> >> /* Empty memory node */ >> memory@0x100000003 { >> device_type = "memory"; >> reg = <0x1 0x3 0x0 0x0>; >> numa-node-id = <3>; >> }; >> >> : >> >> Thanks, >> Gavin >> >> > > Looks good to me. >
Thanks, Drew. v5 was posted to reflect changes, but I don't include Randy's r-b because too much changes introduced. Hopefully, Randy can take a look on v5 when getting a chance.
Thanks, Gavin
| |