linux-kernel - Re: [RESEND PATCH v3 1/2] sched/deadline: Add cpudl_maximum

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Message-ID: <20180601060243.GA184458@joelaf.mtv.corp.google.com>
Date:   Thu, 31 May 2018 23:02:43 -0700
From:   Joel Fernandes <joel@...lfernandes.org>
To:     Byungchul Park <byungchul.park@....com>
Cc:     Peter Zijlstra <peterz@...radead.org>, mingo@...nel.org,
        rostedt@...dmis.org, tglx@...utronix.de, raistlin@...ux.it,
        linux-kernel@...r.kernel.org, juri.lelli@...il.com,
        bristot@...hat.com, kernel-team@....com
Subject: Re: [RESEND PATCH v3 1/2] sched/deadline: Add cpudl_maximum_dl() for
 clean-up

On Fri, Jun 01, 2018 at 12:07:48PM +0900, Byungchul Park wrote:
> 
> 
> On 2018-05-25 14:13, Byungchul Park wrote:
> > 
> > 
> > On 2018-05-09 15:33, Byungchul Park wrote:
> > > On Thu, Jan 11, 2018 at 10:07:16AM +0100, Peter Zijlstra wrote:
> > > > 
> > > > 
> > > > Sorry for the huge delay on this, but I'll have to postpone further.
> > > > Still busy with meltdown/spectre stuff.
> > > 
> > > Please consider this. Even though it's not a big bug, anyway leading
> > > mis-behavior in certain situaions.
> > 
> > Could you see this patches, it's been too long since the start tho?
> 
> Please, any opinion.

Just my opinion: this patch [1] is just a cosmetic change. I would argue that
there's no readability improvement by wrapping up elements[0].dl. Infact I
even feel that the elements[0].cpu should directly be accessed since both
.cpu and .dl for the 0th element are directly accessed only from one place
(cpudl_find) and only one time, and explicitly accessing index 0 makes it
more clear that this is the root of the max-heap.

IOW I don't see any benefit in hiding it behind a wrapper which hides the
fact that we're accessing the root of the max heap, but I don't terribly hate
this patch and I'm Ok if maintainers and other reviewers think its worth it.

thanks,

 - Joel

[1] https://patchwork.kernel.org/patch/10149099/