From: Juri Lelli <juri.lelli@arm.com>
To: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
"Rafael J. Wysocki" <rafael@kernel.org>,
Linux PM list <linux-pm@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Viresh Kumar <viresh.kumar@linaro.org>,
Steve Muckle <steve.muckle@linaro.org>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH v10 1/3] cpufreq: Add mechanism for registering utilization update callbacks
Date: Mon, 22 Feb 2016 09:42:46 +0000 [thread overview]
Message-ID: <20160222094246.GC27380@e106622-lin> (raw)
In-Reply-To: <1882532.OhsNMeyWOd@vostro.rjw.lan>
Hi Rafael,
On 19/02/16 23:26, Rafael J. Wysocki wrote:
> On Friday, February 19, 2016 05:26:04 PM Juri Lelli wrote:
> > Hi Srinivas,
> >
> > On 19/02/16 08:42, Srinivas Pandruvada wrote:
> > > On Fri, 2016-02-19 at 08:09 +0000, Juri Lelli wrote:
> > > Hi Juri,
> > > > >
> > > > Hi Rafael,
> > > >
> > > > On 18/02/16 21:22, Rafael J. Wysocki wrote:
> > > > > On Mon, Feb 15, 2016 at 10:47 PM, Rafael J. Wysocki <rjw@rjwysocki.
> > > > > net> wrote:
> > > > > > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> > > > > >
> > > >
> > > [...]
> > >
> > > > However, I still don't quite get why we want to introduce an
> > > > interface
> > > > for explicit passing of util and max if we are not using such
> > > > parameters
> > > > yet. Also, I couldn't find any indication of how such parameters will
> > > > be
> > > > used in the future. If what we need today is a periodic kick for
> > > > cpufreq
> > > > governors that need it, we should simply do how we already do for RT
> > > > and
> > > > DL, IMHO. Also because the places where the current hooks reside
> > > > might
> > > > not be the correct and useful one once we'll start using the
> > > > utilization
> > > > parameters. I could probably make a case for DL where we should place
> > > > hooks in admission control path (or somewhere else when more
> > > > sophisticated mechanisms we'll be in place) rather then in the
> > > > periodic
> > > > tick.
> > > We did experiments using util/max in intel_pstate. For some benchmarks
> > > there were regression of 4 to 5%, for some benchmarks it performed at
> > > par with getting utilization from the processor. Further optimization
> > > in the algorithm is possible and still in progress. Idea is that we can
> > > change P-State fast enough and be more reactive. Once I have good data,
> > > I will send to this list. The algorithm can be part of the cpufreq
> > > governor too.
> > >
> >
> > Thanks for your answer. What you are experimenting with looks really
> > interesting and I'm certainly more than interested in looking at your
> > findings and patches when they will hit the list.
> >
> > My point was more on what we can look at today, though. Without a clear
> > understanding about how and where util and max will be used and from
> > which scheduler paths such information should come from, it is a bit
> > difficult to tell if the current interface and hooks are fine, IMHO.
>
> As I've just said, I may be able to show something shortly.
>
> > I'd suggest we leave this part to the discussion we will have once your
> > proposal will be public; and to facilitate that we should remove those
> > arguments from the current interface.
>
> I'm not really sure how this will help apart from removing some tiny extra
> overhead that is expected to be temporary anyway.
>
> That said, since both you and Steve are making the point that the utilization
> arguments are problematic and I'd really like to be able to make progress here,
> I don't have any fundamental problems with dropping them for the time being,
> but I'm not going to rebase the 50+ commits I have queued up on top of the
> $subject patch.
>
> So I can apply something like the appended patch if that helps to address
> your concerns.
>
> Thanks,
> Rafael
>
>
> ---
> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> Subject: [PATCH] cpufreq: Rework the scheduler hooks for triggering updates
>
> Commit fe7034338ba0 (cpufreq: Add mechanism for registering
> utilization update callbacks) added cpufreq_update_util() to be
> called by the scheduler (from the CFS part) on utilization updates.
> The goal was to allow CFS to pass utilization information to cpufreq
> and to trigger it to evaluate the frequency/voltage configuration
> (P-state) of every CPU on a regular basis.
>
> However, the last two arguments of that function are never used by
> the current code, so CFS might simply call cpufreq_trigger_update()
> instead of it.
>
> For this reason, drop the last two arguments of cpufreq_update_util(),
> rename it to cpufreq_trigger_update() and modify CFS to call it.
>
> Moreover, since the utilization is not involved in that now, rename
> data types, functions and variables related to cpufreq_trigger_update()
> to reflect that (eg. struct update_util_data becomes struct
> freq_update_hook and so on).
>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This patch looks good to me. I didn't yet test it, but it shouldn't
break things AFAICT.
Thanks a lot for taking the time for this cleanup.
Best,
- Juri
next prev parent reply other threads:[~2016-02-22 9:41 UTC|newest]
Thread overview: 134+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-29 22:52 [PATCH 0/3] cpufreq: Replace timers with utilization update callbacks Rafael J. Wysocki
2016-01-29 22:53 ` [PATCH 1/3] cpufreq: Add a mechanism for registering " Rafael J. Wysocki
2016-02-04 3:31 ` Viresh Kumar
2016-01-29 22:56 ` [PATCH 2/3] cpufreq: intel_pstate: Replace timers with " Rafael J. Wysocki
2016-01-29 22:59 ` [PATCH 3/3] cpufreq: governor: " Rafael J. Wysocki
2016-02-03 1:16 ` [Update][PATCH " Rafael J. Wysocki
2016-02-04 4:49 ` Viresh Kumar
2016-02-04 10:54 ` Rafael J. Wysocki
2016-02-05 1:28 ` [PATCH 3/3 v3] " Rafael J. Wysocki
2016-02-05 6:50 ` Viresh Kumar
2016-02-05 13:36 ` Rafael J. Wysocki
2016-02-05 14:47 ` Viresh Kumar
2016-02-05 23:10 ` Rafael J. Wysocki
2016-02-07 9:10 ` Viresh Kumar
2016-02-07 14:43 ` Rafael J. Wysocki
2016-02-08 2:08 ` Rafael J. Wysocki
2016-02-08 11:52 ` Viresh Kumar
2016-02-08 12:52 ` Rafael J. Wysocki
2016-02-08 13:40 ` Rafael J. Wysocki
2016-02-05 23:01 ` Rafael J. Wysocki
2016-02-06 3:40 ` [PATCH 3/3 v4] " Rafael J. Wysocki
2016-02-07 9:20 ` Viresh Kumar
2016-02-07 14:36 ` Rafael J. Wysocki
2016-02-07 14:50 ` [PATCH 3/3 v5] " Rafael J. Wysocki
2016-02-07 15:36 ` Viresh Kumar
2016-02-09 10:01 ` Gautham R Shenoy
2016-02-09 18:49 ` Rafael J. Wysocki
2016-02-03 22:20 ` [PATCH 0/3] cpufreq: " Rafael J. Wysocki
2016-02-04 0:08 ` Srinivas Pandruvada
2016-02-04 17:16 ` Rafael J. Wysocki
2016-02-04 10:51 ` Juri Lelli
2016-02-04 17:19 ` Rafael J. Wysocki
2016-02-08 23:06 ` Rafael J. Wysocki
2016-02-09 0:39 ` Steve Muckle
2016-02-09 1:01 ` Rafael J. Wysocki
2016-02-09 20:05 ` Rafael J. Wysocki
2016-02-10 1:02 ` Steve Muckle
2016-02-10 1:57 ` Rafael J. Wysocki
2016-02-10 3:09 ` Rafael J. Wysocki
2016-02-10 19:47 ` Steve Muckle
2016-02-10 21:49 ` Rafael J. Wysocki
2016-02-10 22:07 ` Steve Muckle
2016-02-10 22:12 ` Rafael J. Wysocki
2016-02-11 11:59 ` Peter Zijlstra
2016-02-11 12:24 ` Juri Lelli
2016-02-11 15:26 ` Peter Zijlstra
2016-02-11 18:23 ` Vincent Guittot
2016-02-12 14:04 ` Peter Zijlstra
2016-02-12 14:48 ` Vincent Guittot
2016-03-01 13:58 ` Peter Zijlstra
2016-03-01 14:17 ` Juri Lelli
2016-03-01 14:24 ` Peter Zijlstra
2016-03-01 14:26 ` Peter Zijlstra
2016-03-01 14:42 ` Juri Lelli
2016-03-01 15:04 ` Peter Zijlstra
2016-03-01 19:49 ` Rafael J. Wysocki
2016-03-01 14:58 ` Vincent Guittot
2016-02-11 17:06 ` Steve Muckle
2016-02-11 17:30 ` Peter Zijlstra
2016-02-11 17:34 ` Rafael J. Wysocki
2016-02-11 17:38 ` Peter Zijlstra
2016-02-11 18:52 ` Steve Muckle
2016-02-11 19:04 ` Rafael J. Wysocki
2016-02-12 13:43 ` Rafael J. Wysocki
2016-02-12 14:10 ` Peter Zijlstra
2016-02-12 16:01 ` Rafael J. Wysocki
2016-02-12 16:15 ` Rafael J. Wysocki
2016-02-12 16:53 ` Ashwin Chaugule
2016-02-12 23:14 ` Rafael J. Wysocki
2016-02-12 17:02 ` Doug Smythies
2016-02-12 23:17 ` Rafael J. Wysocki
2016-02-10 12:33 ` Juri Lelli
2016-02-10 13:23 ` Rafael J. Wysocki
2016-02-10 14:03 ` Juri Lelli
2016-02-10 14:26 ` Rafael J. Wysocki
2016-02-10 14:46 ` Juri Lelli
2016-02-10 15:46 ` Rafael J. Wysocki
2016-02-10 16:05 ` Juri Lelli
2016-02-11 11:51 ` Peter Zijlstra
2016-02-11 12:08 ` Rafael J. Wysocki
2016-02-11 15:29 ` Peter Zijlstra
2016-02-11 15:58 ` Rafael J. Wysocki
2016-02-11 20:47 ` Rafael J. Wysocki
2016-02-10 15:17 ` [PATCH v6 " Rafael J. Wysocki
2016-02-10 15:21 ` [PATCH v6 1/3] cpufreq: Add mechanism for registering " Rafael J. Wysocki
2016-02-10 23:01 ` [PATCH v7 " Rafael J. Wysocki
2016-02-11 17:30 ` [PATCH v8 " Rafael J. Wysocki
2016-02-12 13:16 ` [PATCH v9 " Rafael J. Wysocki
2016-02-15 21:47 ` [PATCH v10 " Rafael J. Wysocki
2016-02-18 20:22 ` Rafael J. Wysocki
2016-02-19 8:09 ` Juri Lelli
2016-02-19 16:42 ` Srinivas Pandruvada
2016-02-19 17:26 ` Juri Lelli
2016-02-19 22:26 ` Rafael J. Wysocki
2016-02-22 9:42 ` Juri Lelli [this message]
2016-02-22 21:41 ` Rafael J. Wysocki
2016-02-23 11:10 ` Juri Lelli
2016-02-24 1:52 ` Rafael J. Wysocki
2016-02-22 10:45 ` Viresh Kumar
2016-02-19 17:28 ` Steve Muckle
2016-02-19 22:35 ` Rafael J. Wysocki
2016-02-23 3:58 ` Steve Muckle
2016-02-22 10:52 ` Peter Zijlstra
2016-02-22 14:33 ` Vincent Guittot
2016-02-22 15:31 ` Peter Zijlstra
2016-02-22 14:40 ` Juri Lelli
2016-02-22 15:42 ` Peter Zijlstra
2016-02-22 21:46 ` Rafael J. Wysocki
2016-02-19 22:14 ` Rafael J. Wysocki
2016-02-22 9:32 ` Juri Lelli
2016-02-22 21:26 ` Rafael J. Wysocki
2016-02-23 11:01 ` Juri Lelli
2016-02-24 2:01 ` Rafael J. Wysocki
2016-03-08 19:24 ` Michael Turquette
2016-03-08 20:40 ` Rafael J. Wysocki
[not found] ` <20160308220632.4103.13377@quark.deferred.io>
2016-03-08 22:43 ` Rafael J. Wysocki
2016-03-09 12:35 ` Peter Zijlstra
2016-03-09 13:22 ` Rafael J. Wysocki
2016-03-09 13:32 ` Ingo Molnar
2016-03-09 13:39 ` Rafael J. Wysocki
2016-03-10 2:12 ` Vincent Guittot
2016-02-10 15:25 ` [PATCH v6 2/3] cpufreq: intel_pstate: Replace timers with " Rafael J. Wysocki
2016-02-10 15:36 ` [PATCH v6 3/3] cpufreq: governor: " Rafael J. Wysocki
2016-02-10 23:11 ` [PATCH v6 0/3] cpufreq: " Doug Smythies
2016-02-10 23:17 ` Rafael J. Wysocki
2016-02-11 22:50 ` Doug Smythies
2016-02-11 23:28 ` Rafael J. Wysocki
2016-02-12 1:02 ` Doug Smythies
2016-02-12 1:20 ` Rafael J. Wysocki
2016-02-12 7:25 ` Doug Smythies
2016-02-12 13:39 ` Rafael J. Wysocki
2016-02-12 17:33 ` Doug Smythies
2016-02-12 23:21 ` Rafael J. Wysocki
2016-02-11 6:02 ` Srinivas Pandruvada
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