linux-kernel - Re: [RFC GIT PULL] sched; Fix a few missing rq clock updates

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Date:	Tue, 14 May 2013 14:46:43 +0200
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Ingo Molnar <mingo@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Li Zhong <zhong@...ux.vnet.ibm.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Paul Turner <pjt@...gle.com>, Mike Galbraith <efault@....de>
Subject: Re: [RFC GIT PULL] sched; Fix a few missing rq clock updates

On Tue, May 14, 2013 at 01:57:33PM +0200, Peter Zijlstra wrote:
> On Fri, Apr 12, 2013 at 01:50:57AM +0200, Frederic Weisbecker wrote:
> > Hi,
> > 
> > So I revisited the rq clock series I had for dynticks. The patches
> > actually were about upstream issues so I refactored the fixes
> > under that angle and gave up with the wrong asumption that rq
> > clock relies on the tick for its updates.
> > 
> > Patches 1-4 fix some missing updates. Additionally I removed
> > 2 of these updates from the previous set:
> > 
> > * No need to update the rq clock on idle_balance() because it should
> > follow a call to deactivate_task() (unless TIF_NEED_RESCHED is set
> > on idle without new task on the runqueue, not sure we want to cover that).
> > 
> > * No need to update for try_to_wake_up_local() -> ttwu_do_wakeup() -> check_preempt_curr()
> >   as it's following deactivate_task().
> > 
> > Patch 5 brings accessors that will be necessary to settle an rq clock
> > debugging engine. What remains is to tag scheduler's entry/exit points
> > and report missing or redundant update_rq_clock() before calls to
> > rq_clock() and rq_clock_task().
> 
> Just noticed this queue was still sitting in the INBOX, I took it and will
> soon-ish hand to Ingo.

Thanks a lot!
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