linux-kernel - Re: 4.3 group scheduling regression

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Message-ID: <20151013080716.GQ3604@twins.programming.kicks-ass.net>
Date:	Tue, 13 Oct 2015 10:07:16 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Yuyang Du <yuyang.du@...el.com>
Cc:	Mike Galbraith <umgwanakikbuti@...il.com>,
	linux-kernel@...r.kernel.org
Subject: Re: 4.3 group scheduling regression

On Tue, Oct 13, 2015 at 03:32:47AM +0800, Yuyang Du wrote:
> On Mon, Oct 12, 2015 at 01:47:23PM +0200, Peter Zijlstra wrote:
> > 
> > Also, should we do the below? At this point se->on_rq is still 0 so
> > reweight_entity() will not update (dequeue/enqueue) the accounting, but
> > we'll have just accounted the 'old' load.weight.
> > 
> > Doing it this way around we'll first update the weight and then account
> > it, which seems more accurate.
>  
> I think the original looks ok.
> 
> The account_entity_enqueue() adds child entity's load.weight to parent's load:
> 
> update_load_add(&cfs_rq->load, se->load.weight)
> 
> Then recalculate the shares.
> 
> Then reweight_entity() resets the parent entity's load.weight.

Yes, some days I should just not be allowed near a keyboard :)
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