[lkml]   [2020]   [Apr]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH] sched/arm64: store cpu topology before notify_cpu_starting

On 2020/4/1 21:23, Valentin Schneider wrote:
> (+LAKML, +Sudeep)
> On Wed, Apr 01 2020, Cheng Jian 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.
> I haven't been following the sched core stuff closely; can't this
> rq->core assignment be done in sched_cpu_activate() instead? We already
> look at the cpu_smt_mask() in there, and it is valid (we go through the
> entirety of secondary_start_kernel() before getting anywhere near
> I don't think this breaks anything, but without this dependency in
> sched_cpu_starting() then there isn't really a reason for this move.

Yes, it is correct to put the rq-> core assignment in sched_cpu_active().

The cpu_smt_mask is already valid here.

I have made such an attempt on my own branch and passed the test.

Thank you.

    -- Cheng Jian

 \ /
  Last update: 2020-04-06 10:01    [W:0.147 / U:0.980 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site