Re: [PATCH] sched/arm64: store cpu topology before notify_cpu_starting

chengjian (D)
2020-04-10T13:49:39Z

On 2020/4/10 1:54, Joel Fernandes wrote:
> On Wed, Apr 1, 2020 at 7:27 AM Cheng Jian <cj.chengjian@huawei.com> wrote:
>> when SCHED_CORE enabled, sched_cpu_starting() uses thread_sibling as
>> SMT_MASK to initialize rq->core, but only after store_cpu_topology(),
>> the thread_sibling is ready for use.
>>
>> notify_cpu_starting()
>> -> sched_cpu_starting() # use thread_sibling
>>
>> store_cpu_topology(cpu)
>> -> update_siblings_masks # set thread_sibling
>>
>> Fix this by doing notify_cpu_starting later, just like x86 do.
>>
>> Signed-off-by: Cheng Jian <cj.chengjian@huawei.com>
> Just a high-level question, why does core-scheduling matter on ARM64?
> Is it for HPC workloads?
>
> Thanks,
>
> - Joel

Hi, Joel

I am analyzing the mainline scheduling patches and find this problem.

ARM has some platforms that support SMT, and provides some emulate

can be used.

Thanks.

--Cheng Jian