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Date: Tue, 15 Oct 2013 13:35:56 +0200
From: Juri Lelli <juri.lelli@gmail.com>
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To: Peter Zijlstra <peterz@infradead.org>
CC: Ingo Molnar <mingo@kernel.org>, tglx@linutronix.de, mingo@redhat.com,
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Subject: Re: [PATCH 12/14] sched: make dl_bw a sub-quota of rt_bw
References: <1381747426-31334-1-git-send-email-juri.lelli@gmail.com> <1381747426-31334-13-git-send-email-juri.lelli@gmail.com> <20131014140618.GA26604@gmail.com> <525D1234.5060001@gmail.com> <20131015102621.GE10651@twins.programming.kicks-ass.net>
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On 10/15/2013 12:26 PM, Peter Zijlstra wrote:
> On Tue, Oct 15, 2013 at 12:00:20PM +0200, Juri Lelli wrote:
>> On 10/14/2013 04:06 PM, Ingo Molnar wrote:
>>>
>>> * Juri Lelli <juri.lelli@gmail.com> wrote:
>>>
>>>> +#ifdef CONFIG_SMP
>>>> +		struct dl_bw *dl_b = &cpu_rq(i)->rd->dl_bw;
>>>> +#else
>>>> +		struct dl_bw *dl_b = &cpu_rq(i)->dl.dl_bw;
>>>> +#endif
>>>
>>>> +#ifdef CONFIG_SMP
>>>> +		struct dl_bw *dl_b = &cpu_rq(i)->rd->dl_bw;
>>>> +#else
>>>> +		struct dl_bw *dl_b = &cpu_rq(i)->dl.dl_bw;
>>>> +#endif
>>>
>>> Btw., this kind of SMP/UP assymetry pattern really sucks. Why not make UP 
>>> use the SMP data structure, even if it's degenerate?
>>>
>>
>> Yes, I don't like it either, but that comes from the fact that it seemed to me
>> that, semantically, bandwidth for -deadline tasks has to be associated to the
>> single runqueue in UP and to the root_domain for SMP. In UP root_domain is
>> compiled out, so I'm not sure to understand what you suggest. I could probably
>> let dl_bw live on runqueues with the assumption that all the runqueues from the
>> same root_domain have the same dl_bw, that represents the dl_bw of the
>> root_domain. But I don't like this replication either :(.
> 
> #ifdef CONFIG_SMP
> 
> static inline struct dl_bw *dl_bw_of(int i)
> {
> 	return &cpu_rq(i)->rd->dl_bw;
> }
> 
> #else
> 
> static inline struct dl_bw *dl_bw_of(int i)
> {
> 	return &cpu_rq(i)->dl.dl_bw;
> }
> 
> #endif
> 
> ?
> 

Yes, way better.

Thanks,

- Juri