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From: Byungchul Park <byungchul.park@lge.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: mingo@kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] sched/fair: Fix update_min_vruntime() to get proper min_vruntime
Date: Fri, 9 Sep 2016 11:46:00 +0900	[thread overview]
Message-ID: <20160909024559.GC2279@X58A-UD3R> (raw)
In-Reply-To: <20160906084839.GG10153@twins.programming.kicks-ass.net>

On Tue, Sep 06, 2016 at 10:48:39AM +0200, Peter Zijlstra wrote:
> On Tue, Sep 06, 2016 at 02:05:17PM +0900, Byungchul Park wrote:
> > From 295895be8befbab040d6054bb8186c03daabcedd Mon Sep 17 00:00:00 2001
> > From: Byungchul Park <byungchul.park@lge.com>
> > Date: Tue, 6 Sep 2016 12:22:26 +0900
> > Subject: [PATCH] sched/fair: Fix update_min_vruntime() to get proper
> >  min_vruntime
> > 
> > Commit 97a7142 'sched/fair: Make update_min_vruntime() more readable'
> > introduces a bug that cfs_rq gets a wrong min_vruntime if
> > !cfs_rq->rb_leftmost && cfs_rq->curr. This fixes it and makes it more
> > readable and simple.
> 
> Urgh, I actually stared at that patch for quite a time and somehow
> convinced myself it was good. I actually considered that scenario I
> think.
> 
> /me thinks more..
> 
> Argh, I'm an idiot, you're right. By using min_vruntime() on
> cfs_rq->curr we take the leftmost and fail to advance min_vruntime in
> that case.
> 
> I'll ask Ingo to take the patch out.

Ok. But I think the combined one is more readable.
Don't you think so. It's ok even if you don't.

Thank you,
Byungchul

      reply	other threads:[~2016-09-09  2:48 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-09-06  5:05 [PATCH] sched/fair: Fix update_min_vruntime() to get proper min_vruntime Byungchul Park
2016-09-06  8:48 ` Peter Zijlstra
2016-09-09  2:46   ` Byungchul Park [this message]

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