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Message-ID: <52B1753A.7060501@arm.com>
Date: Wed, 18 Dec 2013 10:13:14 +0000
From: Chris Redpath <chris.redpath@arm.com>
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To: "bsegall@google.com" <bsegall@google.com>
CC: Peter Zijlstra <peterz@infradead.org>, "pjt@google.com" <pjt@google.com>,
        "mingo@redhat.com" <mingo@redhat.com>,
        "alex.shi@linaro.org" <alex.shi@linaro.org>,
        Morten Rasmussen <Morten.Rasmussen@arm.com>,
        Dietmar Eggemann <Dietmar.Eggemann@arm.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Vincent Guittot <vincent.guittot@linaro.org>,
        Frederic Weisbecker <fweisbec@gmail.com>,
        Chris Redpath <Chris.Redpath@arm.com>
Subject: Re: [PATCH 2/2] sched: update runqueue clock before migrations away
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On 17/12/13 18:03, bsegall@google.com wrote:
> __synchronize_entity_decay will decay load_avg_contrib in order to
> figure out how much to remove from old_cfs_rq->blocked_load.
> update_entity_load_avg will update the underlying runnable_avg_sum/period that
> is used to update load_avg_contrib.
>
> (Normally we update runnable_avg_sum, which updates load_avg_contrib via
> __update_entity_load_avg_contrib. Here we go in the reverse direction
> because we don't hold the right rq locks at the right times.)
>

Thanks Ben, got it now. The only question remaining for me to figure out 
is if I need to include the missed tick time in the contrib decay or not 
- I definitely need to include it in the negative decay count we send 
through a migration. I'll go and check the places we use the removed 
load and update blocked load again.