Re: [PATCH 7/7] sched/fair: Rename weighted_cpuload() to cpu_load()

[Dietmar Eggemann]

On 5/27/19 9:13 PM, Peter Zijlstra wrote:
> On Mon, May 27, 2019 at 12:24:07PM -0400, Rik van Riel wrote:
>> On Mon, 2019-05-27 at 07:21 +0100, Dietmar Eggemann wrote:
>>> This is done to align the per cpu (i.e. per rq) load with the util
>>> counterpart (cpu_util(int cpu)). The term 'weighted' is not needed
>>> since there is no 'unweighted' load to distinguish it from.
>>
>> I can see why you want to make cpu_util() and cpu_load()
>> have the same parameter, but ...
>>
>>> @@ -7931,7 +7928,7 @@ static inline void update_sg_lb_stats(struct
>>> lb_env *env,
>>>  		if ((env->flags & LBF_NOHZ_STATS) &&
>>> update_nohz_stats(rq, false))
>>>  			env->flags |= LBF_NOHZ_AGAIN;
>>>  
>>> -		sgs->group_load += weighted_cpuload(rq);
>>> +		sgs->group_load += cpu_load(i);
>>>  		sgs->group_util += cpu_util(i);
>>>  		sgs->sum_nr_running += rq->cfs.h_nr_running;
>>
>> ... now we end up dereferencing cpu_rq(cpu) 3 times.
>>
>> I guess per-cpu variables are so cheap that we should
>> never notice, but I thought I'd ask anyway while looking
>> over these patches :)
> 
> I was going to say CSE should fix that, but then I noticed per_cpu
> contains that hideous RELOC_HIDE() thing and I figure that might
> confuse GCC enough to break that :/

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