From: Peter Zijlstra <peterz@infradead.org>
To: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: Ingo Molnar <mingo@kernel.org>,
Jacob Pan <jacob.jun.pan@linux.intel.com>,
Ingo Molnar <mingo@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
John Stultz <john.stultz@linaro.org>,
LKML <linux-kernel@vger.kernel.org>,
Arjan van de Ven <arjan@linux.intel.com>,
Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
Len Brown <len.brown@intel.com>,
Rafael Wysocki <rafael.j.wysocki@intel.com>,
Eduardo Valentin <edubezval@gmail.com>,
Paul Turner <pjt@google.com>
Subject: Re: [PATCH 3/4] sched: introduce synchronized idle injection
Date: Wed, 18 Nov 2015 13:49:46 +0100 [thread overview]
Message-ID: <20151118124946.GF3816@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <20151118122702.GA30184@e105550-lin.cambridge.arm.com>
On Wed, Nov 18, 2015 at 12:27:04PM +0000, Morten Rasmussen wrote:
> On Wed, Nov 18, 2015 at 11:35:41AM +0100, Peter Zijlstra wrote:
> > On Wed, Nov 18, 2015 at 09:36:22AM +0100, Ingo Molnar wrote:
> > > What will such throttling do to latencies, as observed by user-space tasks? What's
> > > the typical expected frequency of the throttling frequency that you are targeting?
> >
> > The default has 5ms (iirc) of forced idle, so depending on what you do,
> > noticeable to outright painful.
>
> IIUC, it is 5 ticks, not ms.
The code uses hrtimers (badly), this means there _should_ not be a tick
dependency.
> Which raises the question, doesn't that mean that we get disturbed four
> times on each cpu during the forced idle period? So idle injection only
> makes sense if the platform has package states with a target residency
> less than a jiffy. Or, do we enter NOHZ idle? I haven't looked closely
> enough to figure out yet.
The idea is to hit NOHZ.
next prev parent reply other threads:[~2015-11-18 12:50 UTC|newest]
Thread overview: 78+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-11-13 19:53 [PATCH 0/4] CFS idle injection Jacob Pan
2015-11-13 19:53 ` [PATCH 1/4] ktime: add a roundup function Jacob Pan
2015-11-13 20:11 ` John Stultz
2015-11-13 22:33 ` Jacob Pan
2015-11-13 20:13 ` Thomas Gleixner
2015-11-13 22:36 ` Jacob Pan
2015-11-13 19:53 ` [PATCH 2/4] timer: relax tick stop in idle entry Jacob Pan
2015-11-13 20:22 ` Thomas Gleixner
2015-11-13 22:24 ` Jacob Pan
2015-11-16 15:06 ` Thomas Gleixner
2015-11-16 21:51 ` Jacob Pan
2015-11-16 22:01 ` Thomas Gleixner
2015-11-17 0:09 ` Jacob Pan
2015-11-19 17:43 ` Jacob Pan
2015-11-19 19:06 ` Peter Zijlstra
2015-11-19 19:21 ` Jacob Pan
2015-11-19 19:59 ` Peter Zijlstra
2015-11-19 23:41 ` Jacob Pan
2015-11-16 22:31 ` Paul E. McKenney
2015-11-16 23:05 ` Jacob Pan
2015-11-16 23:15 ` Jacob Pan
2015-11-16 23:28 ` Paul E. McKenney
2015-11-16 23:32 ` Arjan van de Ven
2015-11-16 23:40 ` Jacob Pan
2015-11-17 0:00 ` Paul E. McKenney
2015-11-16 22:32 ` Josh Triplett
2015-11-16 23:26 ` Paul E. McKenney
2015-11-17 1:41 ` Josh Triplett
2015-11-17 2:53 ` Paul E. McKenney
2015-11-17 2:57 ` Arjan van de Ven
2015-11-17 5:04 ` Paul E. McKenney
2015-11-17 10:24 ` Peter Zijlstra
2015-11-17 12:57 ` Jacob Pan
2015-11-17 13:49 ` Paul E. McKenney
2015-11-13 19:53 ` [PATCH 3/4] sched: introduce synchronized idle injection Jacob Pan
2015-11-13 20:23 ` kbuild test robot
2015-11-18 8:36 ` Ingo Molnar
2015-11-18 10:35 ` Peter Zijlstra
2015-11-18 12:27 ` Morten Rasmussen
2015-11-18 12:49 ` Peter Zijlstra [this message]
2015-11-18 14:04 ` Morten Rasmussen
2015-11-18 14:52 ` Jacob Pan
2015-11-18 15:09 ` Morten Rasmussen
2015-11-18 15:11 ` Jacob Pan
2015-11-18 15:21 ` Thomas Gleixner
2015-11-18 17:03 ` Jacob Pan
2015-11-18 16:04 ` Morten Rasmussen
2015-11-27 9:17 ` Ingo Molnar
2015-11-18 14:10 ` Jacob Pan
2015-11-27 9:17 ` Ingo Molnar
2015-12-02 17:28 ` Jacob Pan
2015-11-18 14:19 ` Arjan van de Ven
2015-11-18 15:44 ` Morten Rasmussen
2015-11-18 15:51 ` Arjan van de Ven
2015-11-19 17:24 ` Morten Rasmussen
2015-11-19 20:09 ` Peter Zijlstra
2015-11-20 9:45 ` Thomas Gleixner
2015-11-20 10:20 ` Peter Zijlstra
2015-11-20 10:58 ` Thomas Gleixner
2015-11-20 12:54 ` Peter Zijlstra
2015-11-20 18:53 ` Thomas Gleixner
2016-01-11 21:50 ` Jacob Pan
2016-01-19 12:06 ` Ingo Molnar
2016-01-19 18:00 ` Jacob Pan
2015-11-24 11:38 ` Jacob Pan
2015-11-23 17:59 ` Jacob Pan
2015-11-23 17:56 ` Javi Merino
2015-11-23 18:07 ` Peter Zijlstra
2015-11-24 9:12 ` Javi Merino
2015-11-24 10:09 ` Peter Zijlstra
2015-11-24 11:10 ` Jacob Pan
2015-11-24 12:00 ` Javi Merino
2015-11-24 18:22 ` Jacob Pan
2015-11-25 9:41 ` Javi Merino
2015-11-13 19:53 ` [PATCH 4/4] sched: add trace event for " Jacob Pan
2015-11-13 20:10 ` kbuild test robot
2015-11-19 14:39 ` Javi Merino
2015-11-19 15:35 ` Jacob Pan
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