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

["Li, Tianyou" <tianyou.li@intel.com>]

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. 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.

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


Regards,

Tianyou