From: Peter Zijlstra <peterz@infradead.org>
To: Ingo Molnar <mingo@kernel.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>,
Chris Metcalf <cmetcalf@tilera.com>,
Christoph Lameter <cl@linux.com>,
Geoff Levand <geoff@infradead.org>,
Gilad Ben Yossef <gilad@benyossef.com>,
Hakan Akkan <hakanakkan@gmail.com>,
Li Zhong <zhong@linux.vnet.ibm.com>,
Namhyung Kim <namhyung.kim@lge.com>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
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
Date: Wed, 10 Apr 2013 13:02:47 +0200 [thread overview]
Message-ID: <1365591767.30071.45.camel@laptop> (raw)
In-Reply-To: <20130410100620.GA28402@gmail.com>
On Wed, 2013-04-10 at 12:06 +0200, Ingo Molnar wrote:
> * 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?
It requires manual iteration of all scheduler operations which is prone
to 'accidents'.
I'd clear at the beginning, but that's more or less the same thing.
We have the .sched.text section but I'm not sure we've been consistent
enough with that to be useful. But otherwise we'd be able to clear on
section entry/exit or so.
next prev parent reply other threads:[~2013-04-10 11:03 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-06 16:45 [RFC GIT PULL] nohz: Full dynticks rq clock handling Frederic Weisbecker
2013-04-06 16:45 ` [PATCH 1/7] sched: Update rq clock on nohz CPU before migrating tasks Frederic Weisbecker
2013-04-08 11:48 ` Ingo Molnar
2013-04-09 9:13 ` Peter Zijlstra
2013-04-09 13:11 ` Frederic Weisbecker
2013-04-06 16:45 ` [PATCH 2/7] sched: Update rq clock on nohz CPU before setting fair group shares Frederic Weisbecker
2013-04-09 9:26 ` Peter Zijlstra
2013-04-09 13:21 ` Frederic Weisbecker
2013-04-10 7:05 ` Peter Zijlstra
2013-04-10 10:06 ` Ingo Molnar
2013-04-10 11:02 ` Peter Zijlstra [this message]
2013-04-10 11:06 ` Ingo Molnar
2013-04-10 11:47 ` Peter Zijlstra
2013-04-10 11:50 ` Ingo Molnar
2013-04-06 16:45 ` [PATCH 3/7] sched: Update rq clock on tickless CPUs before calling check_preempt_curr() Frederic Weisbecker
2013-04-09 13:18 ` Peter Zijlstra
2013-04-09 16:53 ` Frederic Weisbecker
2013-04-06 16:45 ` [PATCH 4/7] sched: Update rq clock earlier in unthrottle_cfs_rq Frederic Weisbecker
2013-04-06 16:45 ` [PATCH 5/7] sched: Update rq clock before idle balancing Frederic Weisbecker
2013-04-06 16:45 ` [PATCH 6/7] sched: Use an accessor to read rq clock Frederic Weisbecker
2013-04-06 16:46 ` [PATCH 7/7] sched: Debug nohz " Frederic Weisbecker
2013-04-10 10:26 ` [RFC GIT PULL] nohz: Full dynticks rq clock handling Peter Zijlstra
2013-04-10 10:29 ` Ingo Molnar
2013-04-11 15:11 ` Frederic Weisbecker
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