Re: [PATCH -tip 14/32] sched: migration changes for core scheduling

[Li, Aubrey]

On 2020/11/24 23:42, Peter Zijlstra wrote:
> On Mon, Nov 23, 2020 at 12:36:10PM +0800, Li, Aubrey wrote:
>>>> +#ifdef CONFIG_SCHED_CORE
>>>> +		/*
>>>> +		 * Skip this cpu if source task's cookie does not match
>>>> +		 * with CPU's core cookie.
>>>> +		 */
>>>> +		if (!sched_core_cookie_match(cpu_rq(cpu), env->p))
>>>> +			continue;
>>>> +#endif
>>>> +
>>>
>>> Any reason this is under an #ifdef? In sched_core_cookie_match() won't
>>> the check for sched_core_enabled() do the right thing even when
>>> CONFIG_SCHED_CORE is not enabed?> 
>> Yes, sched_core_enabled works properly when CONFIG_SCHED_CORE is not
>> enabled. But when CONFIG_SCHED_CORE is not enabled, it does not make
>> sense to leave a core scheduler specific function here even at compile
>> time. Also, for the cases in hot path, this saves CPU cycles to avoid
>> a judgment.
> 
> No, that's nonsense. If it works, remove the #ifdef. Less (#ifdef) is
> more.
> 

Okay, I pasted the refined patch here.
@Joel, please let me know if you want me to send it in a separated thread.

Thanks,
-Aubrey
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