From: Frederic Weisbecker <fweisbec@gmail.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
Byungchul Park <byungchul.park@lge.com>,
Chris Metcalf <cmetcalf@ezchip.com>,
Thomas Gleixner <tglx@linutronix.de>,
Luiz Capitulino <lcapitulino@redhat.com>,
Christoph Lameter <cl@linux.com>,
"Paul E . McKenney" <paulmck@linux.vnet.ibm.com>,
Mike Galbraith <efault@gmx.de>, Rik van Riel <riel@redhat.com>
Subject: Re: [RFC PATCH 4/4] sched: Upload nohz full CPU load on task enqueue/dequeue
Date: Thu, 21 Jan 2016 14:25:28 +0100 [thread overview]
Message-ID: <20160121132525.GA5838@lerouge> (raw)
In-Reply-To: <20160120182503.GP6357@twins.programming.kicks-ass.net>
On Wed, Jan 20, 2016 at 07:25:03PM +0100, Peter Zijlstra wrote:
> On Wed, Jan 20, 2016 at 06:21:07PM +0100, Frederic Weisbecker wrote:
>
> > You mean a periodic call to the above from the housekeepers?
> >
> > I didn't think about doing that because you nacked that approach with
> > scheduler_tick(). This isn't much different.
>
> This does _one_ thing, namely load accounting. scheduler_tick() does a
> whole bunch of things, some which really do not make much sense to do
> remotely.
Ok.
>
> > It means the housekeeper is entirely dedicated to full dynticks CPUs.
>
> Depends on how many there are, and how many housekeepers. I would
> suggest one housekeeper cpu per node or so to make sure this keeps
> working.
That's possible to do.
>
> Then again, these load values aren't super important, esp. not for the
> nohz_full case where you typically don't care about load balancing.
In this case maybe we can assume that these stats don't need precision at
all on nohz full and when the full nohz frame starts, we define
all cpu_load[i] = cpu_load[0] = weighted_cpuload(cpu) and we keep it that way until
the nohz full frame ends. This way we avoid the remote update.
next prev parent reply other threads:[~2016-01-21 13:25 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-13 16:01 [RFC PATCH 0/4] sched: Improve cpu load accounting with nohz Frederic Weisbecker
2016-01-13 16:01 ` [PATCH 1/4] sched: Don't account tickless CPU load on tick Frederic Weisbecker
2016-01-19 13:08 ` Peter Zijlstra
2016-01-19 16:22 ` Frederic Weisbecker
2016-01-19 18:56 ` Peter Zijlstra
2016-01-19 22:33 ` Frederic Weisbecker
2016-01-20 5:43 ` Byungchul Park
2016-01-20 10:26 ` Byungchul Park
2016-01-28 16:01 ` Frederic Weisbecker
2016-01-29 9:50 ` Peter Zijlstra
2016-02-01 10:05 ` Byungchul Park
2016-02-01 10:09 ` [PATCH] sched: calculate sched_clock_cpu without tick handling during nohz Byungchul Park
2016-02-01 10:34 ` [PATCH 1/4] sched: Don't account tickless CPU load on tick Peter Zijlstra
2016-02-01 23:51 ` Byungchul Park
2016-02-02 0:50 ` Byungchul Park
2016-02-01 6:33 ` Byungchul Park
2016-01-20 8:42 ` Thomas Gleixner
2016-01-20 17:36 ` Frederic Weisbecker
2016-01-22 8:40 ` Byungchul Park
2016-01-13 16:01 ` [PATCH 2/4] sched: Consolidate nohz CPU load update code Frederic Weisbecker
2016-01-14 2:30 ` Byungchul Park
2016-01-19 13:13 ` Peter Zijlstra
2016-01-20 0:51 ` Byungchul Park
2016-01-14 5:18 ` Byungchul Park
2016-01-19 13:13 ` Peter Zijlstra
2016-01-19 16:49 ` Frederic Weisbecker
2016-01-20 1:41 ` Byungchul Park
2016-02-29 11:14 ` [tip:sched/core] sched/fair: " tip-bot for Frederic Weisbecker
2016-01-13 16:01 ` [RFC PATCH 3/4] sched: Move cpu load stats functions above fair queue callbacks Frederic Weisbecker
2016-01-13 16:01 ` [RFC PATCH 4/4] sched: Upload nohz full CPU load on task enqueue/dequeue Frederic Weisbecker
2016-01-19 13:17 ` Peter Zijlstra
2016-01-19 17:03 ` Frederic Weisbecker
2016-01-20 9:09 ` Peter Zijlstra
2016-01-20 14:54 ` Frederic Weisbecker
2016-01-20 15:11 ` Thomas Gleixner
2016-01-20 15:19 ` Christoph Lameter
2016-01-20 16:52 ` Frederic Weisbecker
2016-01-20 16:45 ` Frederic Weisbecker
2016-01-20 16:56 ` Peter Zijlstra
2016-01-20 17:21 ` Frederic Weisbecker
2016-01-20 18:25 ` Peter Zijlstra
2016-01-21 13:25 ` Frederic Weisbecker [this message]
2016-01-20 9:03 ` Thomas Gleixner
2016-01-20 14:31 ` Frederic Weisbecker
2016-01-20 14:43 ` Thomas Gleixner
2016-01-20 16:40 ` Frederic Weisbecker
2016-01-20 16:42 ` Christoph Lameter
2016-01-20 16:47 ` Frederic Weisbecker
2016-01-14 21:19 ` [RFC PATCH 0/4] sched: Improve cpu load accounting with nohz Dietmar Eggemann
2016-01-14 21:27 ` Peter Zijlstra
2016-01-14 22:23 ` Dietmar Eggemann
2016-01-15 7:07 ` Byungchul Park
2016-01-15 16:56 ` Dietmar Eggemann
2016-01-18 0:23 ` Byungchul Park
2016-01-19 13:04 ` Peter Zijlstra
2016-01-20 0:48 ` Byungchul Park
2016-01-20 13:04 ` Dietmar Eggemann
2016-02-29 11:14 ` [tip:sched/core] sched/fair: Avoid using decay_load_missed() with a negative value tip-bot for Byungchul Park
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