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Date: Wed, 10 Apr 2013 12:06:20 +0200
From: Ingo Molnar <mingo@kernel.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Alessio Igor Bogani <abogani@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
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        Paul Gortmaker <paul.gortmaker@windriver.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Thomas Gleixner <tglx@linutronix.de>, Paul Turner <pjt@google.com>,
        Mike Galbraith <efault@gmx.de>
Subject: Re: [PATCH 2/7] sched: Update rq clock on nohz CPU before setting
 fair group shares
Message-ID: <20130410100620.GA28402@gmail.com>
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* Peter Zijlstra <peterz@infradead.org> wrote:

> I think Mike once tried something along the lines of keeping a per rq state that 
> got cleared at the end of schedule() but that doesn't catch things like the 
> migrate handlers I think.

We'd need a rq->clock.valid debug flag, which is set by a sched-clock update, and 
cleared by the end of all scheduler operations, not just schedule().

Then sched_clock() could have a pretty efficient assert in it. Are there bugs that 
such an approach would not catch?

Thaks,

	Ingo