linux-kernel - Re: [PATCH v8 1/2] sched/deadline: Add support for SD_PREFER_SIBLING on find_later

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Date:   Tue, 22 Aug 2017 14:53:25 +0900
From:   Byungchul Park <byungchul.park@....com>
To:     Juri Lelli <juri.lelli@....com>
Cc:     peterz@...radead.org, mingo@...nel.org, joel.opensrc@...il.com,
        linux-kernel@...r.kernel.org, juri.lelli@...il.com,
        rostedt@...dmis.org, kernel-team@....com
Subject: Re: [PATCH v8 1/2] sched/deadline: Add support for SD_PREFER_SIBLING
 on find_later_rq()

On Mon, Aug 21, 2017 at 02:44:58PM +0100, Juri Lelli wrote:
> Hi,
> On 18/08/17 17:21, Byungchul Park wrote:
> > It would be better to try to check other siblings first if
> > SD_PREFER_SIBLING is flaged when pushing tasks - migration.
> > 
> > Signed-off-by: Byungchul Park <byungchul.park@....com>
> 
> Mmm, this looks like Peter's proposed patch, maybe add (at least) a
> Suggested-by: him ?

Hi Juri,

Why not. I will add it from the next spin.

BTW, is it enough? I don't know the way I should do, whenever I got
thankful suggestions. I really want to add them as a separate patch
which can be stacked on my patches _if possible_. But in case that
it's better to merge them into one like this, I don't know how.

I mean I will add 'Suggested-by' from now on - I learned what I should
do (at least) in this case thanks to Juri, but I'm still not sure if
it's enough.

Speaking of which, I have something to ask Peterz and Ingo for. I really
want to interact with maintainers actively e.g. asking ways they prefer.
But it takes too much long to get responses from them e.g. at most 2
monthes in case rushing them. I should have decided and done what the
best I think is, than asking.

It would be very appriciated if you pay more attention.

> > @@ -1376,8 +1399,7 @@ static int find_later_rq(struct task_struct *task)
> >  				return this_cpu;
> >  			}
> >  
> > -			best_cpu = cpumask_first_and(later_mask,
> > -							sched_domain_span(sd));
> > +			best_cpu = find_cpu(later_mask, sd, prefer);
> >  			/*
> >  			 * Last chance: if a cpu being in both later_mask
> >  			 * and current sd span is valid, that becomes our
> > @@ -1385,6 +1407,26 @@ static int find_later_rq(struct task_struct *task)
> >  			 * already under consideration through later_mask.
> >  			 */
> 
> It seems that the comment above should be updated as well.

How? Could you explain it more?

Thanks,
Byungchul