Re: [PATCH v9 2/2] mm/memory hotplug/unplug: Optimize zone->contiguous update when changes pfn range

[David Hildenbrand (Arm)]

On 3/11/26 16:02, Li, Tianyou wrote:
> 
> On 3/9/2026 10:26 PM, David Hildenbrand (Arm) wrote:
>> On 3/9/26 01:42, Li, Tianyou wrote:
>>> Hi David, Mike & Other maintainers,
>> Hi!
>>
>>> Just a quick update: Yuan and I created a new patch based on David and
>>> Mike's code, updated the documentation as well, performed the
>>> performance test, double check all the references etc. We observed a
>>> slightly performance regression, not sure it was caused by the
>>> environment configuration or we triggered some unexpected behavior. We
>>> might need a bit more time to investigate. Will send out the patch soon
>>> once we have confirmed data for the performance regression. Thanks.
>> A performance regression would be rather unexpected, unless we somehow
>> don't ever set zone->contiguous=true any more :)
>>
>> In which test / code path did you observe a regression?
> 
> 
> Sorry for the late response, I missed the email by accident. The test is
> simply hotplug and unplug the 256GB memory, the time became 3s instead
> of 2s for some reason compared to previous patch.

Weird, because we should be doing less work :)

> Interestingly, for
> 512GB memory hotplug/unplug, the time remains as 6s. What we planned to
> do are: 1. double/triple check with the same and other servers; 2.
> collect the perf profile to see what is the diff compared with previous
> patch, if the regression consistently persisted.

Sounds good.

> 
> I will work with Yuan on this and hopefully we can have more information
> to be shared here soon. Thanks.

Greta, thanks. Feel free to send out a new version in the meantime.

-- 
Cheers,

David