Re: [PATCH v3 00/12] arm64: Add HOTPLUG_PARALLEL support for secondary CPUs

[Jinjie Ruan]

On 7/7/2026 1:39 AM, Will Deacon wrote:
> Hi Jinjie,
> 
> On Thu, Jun 25, 2026 at 09:34:36AM +0800, Jinjie Ruan wrote:
>> On 6/24/2026 8:16 PM, Will Deacon wrote:
>>> Please just give me the time I asked for. If you want to help out in the
>>> meantime, there are plenty of patches that need reviewing...
>>
>> It was a mistake on my part, and I sincerely apologize for wasting
>> community review resources and disrupting your schedule.
>>
>> I will absolutely back off now and wait for your official series. Lesson
>> learned. Thanks for your patience and for calling me out on this.
> 
> So I've mostly got the old series back on its feet:
> 
>   https://git.kernel.org/pub/scm/linux/kernel/git/will/linux.git/log/?h=cpu-hotplug

Hi Will,

I tested the boot time on the HIP12 hardware based on your patch, as the
other two boards with 32 cores and 64 cores can only be booted using the
5.10 kernel，but the patches are greatly different, and the adaptation is
complex.

Bringup Time Comparison on real hardware (ms, lower is better):

 |     Platform             | Baseline|   P=0   |   P=1   | Delta(%)|
 | -------------------------| ------- | ------- | ------- | ------- |
 | 288-core server(HIP12)   | 21989.6 | 21989.7 | 12915.3 | 41.3%   |

> 
> but there are still two issues left to resolve:
> 
>   1. The printing that can happen before RCU has started. Although I've
>      reduced this somewhat, there are still error paths in e.g.
>      verify_local_cpu_capabilities() that print a message before dying.
> 
>   2. check_local_cpu_capabilities() can mutate the system capability
>      state via update_cpu_capabilities(), so it's really dodgy running
>      that prior to synchronisation.
> 
> Since you've added patches in this series that try to tackle these
> problems, I'll reply on those two so we can figure out how we would like
> to proceed.
> 
> Cheers,
> 
> Will