From: Mike Galbraith <efault@gmx.de>
To: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Luiz Capitulino <lcapitulino@redhat.com>,
LKML <linux-kernel@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Chris Metcalf <cmetcalf@mellanox.com>,
Thomas Gleixner <tglx@linutronix.de>,
Christoph Lameter <cl@linux.com>,
"Paul E . McKenney" <paulmck@linux.vnet.ibm.com>,
Ingo Molnar <mingo@kernel.org>, Rik van Riel <riel@redhat.com>,
Wanpeng Li <kernellwp@gmail.com>
Subject: Re: [RFC PATCH 7/9] housekeeping: Use own boot option, independant from nohz
Date: Tue, 15 Aug 2017 17:15:23 +0200 [thread overview]
Message-ID: <1502810123.1349.71.camel@gmx.de> (raw)
In-Reply-To: <20170815130712.GA16627@lerouge>
On Tue, 2017-08-15 at 15:07 +0200, Frederic Weisbecker wrote:
> On Mon, Aug 14, 2017 at 08:29:46PM +0200, Mike Galbraith wrote:
> > On Mon, 2017-08-14 at 13:34 -0400, Luiz Capitulino wrote:
> > > On Mon, 14 Aug 2017 19:01:09 +0200
> > >
> > > > What is the source of the load balancing inducing such latency when a single
> > > > task is affine to a CPU? If this is idle load balancing, it is now affine to
> > > > housekeepers. If this is task wakeup then it's suprising because select_task_rq()
> > > > is optimized toward single CPU affinity.
> > >
> > > I guess it was idle load balancing, but I don't remember because this
> > > was a few years ago. I think this might be reproducible without using
> > > isolcpus=. I'll give it a try shortly and let you know.
> >
> > idle_balance() can swamp other noise by a couple orders of magnitude,
>
> Ah I missed that one. Is there any way we can also lower the overhead there?
Why? HPC proggies won't benefit from a partially filled pothole any
more that a ~zero ground clearance formula 1 car would. The pothole
intolerant either isolate, killing (most) LB, or they meet a wall.
-Mike
next prev parent reply other threads:[~2017-08-15 15:16 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-21 13:21 [RFC PATCH 0/9] Introduce housekeeping subsystem Frederic Weisbecker
2017-07-21 13:21 ` [RFC PATCH 1/9] housekeeping: Move housekeeping related code to its own file Frederic Weisbecker
2017-07-21 13:21 ` [RFC PATCH 2/9] watchdog: Use housekeeping_cpumask() instead of ad-hoc version Frederic Weisbecker
2017-07-21 13:21 ` [RFC PATCH 3/9] housekeeping: Provide a dynamic off-case to housekeeping_any_cpu() Frederic Weisbecker
2017-07-21 13:21 ` [RFC PATCH 4/9] housekeeping: Make housekeeping cpumask private Frederic Weisbecker
2017-07-21 13:21 ` [RFC PATCH 5/9] housekeeping: Use its own static key Frederic Weisbecker
2017-07-21 13:21 ` [RFC PATCH 6/9] housekeeping: Rename is_housekeeping_cpu to housekeeping_cpu Frederic Weisbecker
2017-07-21 13:21 ` [RFC PATCH 7/9] housekeeping: Use own boot option, independant from nohz Frederic Weisbecker
2017-08-11 19:09 ` Luiz Capitulino
2017-08-12 14:10 ` Frederic Weisbecker
2017-08-13 15:13 ` Luiz Capitulino
2017-08-14 17:01 ` Frederic Weisbecker
2017-08-14 17:34 ` Luiz Capitulino
2017-08-14 18:29 ` Mike Galbraith
2017-08-15 13:07 ` Frederic Weisbecker
2017-08-15 15:15 ` Mike Galbraith [this message]
2017-08-15 15:30 ` Paul E. McKenney
2017-08-15 15:52 ` Christopher Lameter
2017-08-15 15:57 ` Mike Galbraith
2017-08-15 16:26 ` Christopher Lameter
2017-08-16 18:00 ` Mike Galbraith
2017-08-15 15:53 ` Mike Galbraith
2017-07-21 13:21 ` [RFC PATCH 8/9] housekeeping: Move it under own config, independant from NO_HZ Frederic Weisbecker
2017-07-21 13:21 ` [RFC PATCH 9/9] workqueue: Affine unbound workqueues to housekeeping cpumask Frederic Weisbecker
2017-07-21 19:48 ` [RFC PATCH 0/9] Introduce housekeeping subsystem Chris Metcalf
2017-08-10 12:54 ` Frederic Weisbecker
2017-08-10 13:57 ` Chris Metcalf
2017-08-11 6:36 ` Mike Galbraith
2017-08-11 15:01 ` Frederic Weisbecker
2017-08-11 19:22 ` Luiz Capitulino
2017-08-11 15:08 ` Chris Metcalf
2017-08-11 15:35 ` Christopher Lameter
2017-08-11 15:50 ` Chris Metcalf
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