[RFP] LPC thermal track

[RFP] LPC thermal track

[Eduardo Valentin]

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Hello all,

I've created a proposal for a thermal microconference track on the LPC
2015 [1]. The basic idea is to get thermal developers together and
discuss the thermal role within the Linux environment, from kernel and
userspace perspective.

A initial proposal for the topics to be discussed are:
. Closed loop control governors
. Sensor API
. Thermal class: split of temperature sensor device and thermal driver
. Improvements on OF-thermal
. Devfreq vs. clock cooling
. Power model based policies
. User space tools
. User space governors

If you have interest, or if you have ideas on how to improve the
framework, reply to this email and add it to the wiki. 

Add your name in the list of participants as well. Also, if you feel
like giving a talk on the topic, let's add it to the topic list.

Currently I am simple checking what would be the level of interest to
have this topic as a LPC microconference.

BR,

Eduardo Valentin


[1] - http://wiki.linuxplumbersconf.org/2015:thermal

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Re: [RFP] LPC thermal track

[Punit Agrawal]

Hi Eduardo,

Thanks for proposing a thermal micro-conference. It would be good to 
discuss the direction things are heading with regards to thermal in linux.

On 27/03/15 00:02, Eduardo Valentin wrote:
> Hello all,
>
> I've created a proposal for a thermal microconference track on the LPC
> 2015 [1]. The basic idea is to get thermal developers together and
> discuss the thermal role within the Linux environment, from kernel and
> userspace perspective.
>
> A initial proposal for the topics to be discussed are:
> . Closed loop control governors
> . Sensor API
> . Thermal class: split of temperature sensor device and thermal driver
> . Improvements on OF-thermal
> . Devfreq vs. clock cooling
> . Power model based policies
> . User space tools
> . User space governors
>
> If you have interest, or if you have ideas on how to improve the
> framework, reply to this email and add it to the wiki.
>

I'd like to propose -

. Co-ordination among cooling-devices in the system

In workloads that involve multiple devices such as camera+CPUs+image 
singal processor or camera+video encoding, etc. often there are 
dependencies across multiple devices' performance states to achieve 
minimum acceptable performance (24fps HD encode for example). When 
thermally constrained it would help to have some mechanisms to 
co-ordinate their performance control. The power allocator governor 
attempts to solve some of these problems but it would be good to have a 
wider discussion on enabling more scenarios.


> Add your name in the list of participants as well. Also, if you feel
> like giving a talk on the topic, let's add it to the topic list.
>

Done.

Cheers,
Punit

> Currently I am simple checking what would be the level of interest to
> have this topic as a LPC microconference.
>
> BR,
>
> Eduardo Valentin
>
>
> [1] - http://wiki.linuxplumbersconf.org/2015:thermal
>

Re: [RFP] LPC thermal track

[Eduardo Valentin]

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Hello Punit,

On Fri, Mar 27, 2015 at 11:47:45AM +0000, Punit Agrawal wrote:
> Hi Eduardo,
> 
> Thanks for proposing a thermal micro-conference. It would be good to 
> discuss the direction things are heading with regards to thermal in linux.
> 

Great!

Let's see if we can get enough entropy to get it approved.

> On 27/03/15 00:02, Eduardo Valentin wrote:
> > Hello all,
> >
> > I've created a proposal for a thermal microconference track on the LPC
> > 2015 [1]. The basic idea is to get thermal developers together and
> > discuss the thermal role within the Linux environment, from kernel and
> > userspace perspective.
> >
> > A initial proposal for the topics to be discussed are:
> > . Closed loop control governors
> > . Sensor API
> > . Thermal class: split of temperature sensor device and thermal driver
> > . Improvements on OF-thermal
> > . Devfreq vs. clock cooling
> > . Power model based policies
> > . User space tools
> > . User space governors
> >
> > If you have interest, or if you have ideas on how to improve the
> > framework, reply to this email and add it to the wiki.
> >
> 
> I'd like to propose -
> 
> . Co-ordination among cooling-devices in the system
> 
> In workloads that involve multiple devices such as camera+CPUs+image 
> singal processor or camera+video encoding, etc. often there are 
> dependencies across multiple devices' performance states to achieve 
> minimum acceptable performance (24fps HD encode for example). When 
> thermally constrained it would help to have some mechanisms to 
> co-ordinate their performance control. The power allocator governor 
> attempts to solve some of these problems but it would be good to have a 
> wider discussion on enabling more scenarios.
> 

Sounds good to me. It would be interesting to see if plumbing is
required in the framework itself.

> 
> > Add your name in the list of participants as well. Also, if you feel
> > like giving a talk on the topic, let's add it to the topic list.
> >
> 
> Done.
> 

Can you please also add you name as presenter of this topic?

> Cheers,
> Punit
> 
> > Currently I am simple checking what would be the level of interest to
> > have this topic as a LPC microconference.
> >
> > BR,
> >
> > Eduardo Valentin
> >
> >
> > [1] - http://wiki.linuxplumbersconf.org/2015:thermal
> >
> 

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Re: [RFP] LPC thermal track

[Srinivas Pandruvada]

On Fri, 2015-03-27 at 11:47 +0000, Punit Agrawal wrote: 
> Hi Eduardo,
> 
> Thanks for proposing a thermal micro-conference. It would be good to 
> discuss the direction things are heading with regards to thermal in linux.
> 
> On 27/03/15 00:02, Eduardo Valentin wrote:
> > Hello all,
> >
> > I've created a proposal for a thermal microconference track on the LPC
> > 2015 [1]. The basic idea is to get thermal developers together and
> > discuss the thermal role within the Linux environment, from kernel and
> > userspace perspective.
> >
> > A initial proposal for the topics to be discussed are:
> > . Closed loop control governors
> > . Sensor API
> > . Thermal class: split of temperature sensor device and thermal driver
> > . Improvements on OF-thermal
> > . Devfreq vs. clock cooling
> > . Power model based policies
> > . User space tools
> > . User space governors
> >
> > If you have interest, or if you have ideas on how to improve the
> > framework, reply to this email and add it to the wiki.
What about
Some enhancement in thermal zone user space I/F for user space thermal
controllers
- Better support for virtual temperature sensors which depends on other
sensors. 
- Support for Linux IIO style scale and offset in thermal zone
temperature calculation.
- /dev interface for pushing thermal samples instead of raw read of
temperature to improve performances and push sample instead of pull from
user space.

Thanks,
Srinivas 
> >
> 
> I'd like to propose -
> 
> . Co-ordination among cooling-devices in the system
> 
> In workloads that involve multiple devices such as camera+CPUs+image 
> singal processor or camera+video encoding, etc. often there are 
> dependencies across multiple devices' performance states to achieve 
> minimum acceptable performance (24fps HD encode for example). When 
> thermally constrained it would help to have some mechanisms to 
> co-ordinate their performance control. The power allocator governor 
> attempts to solve some of these problems but it would be good to have a 
> wider discussion on enabling more scenarios.
> 
> 
> > Add your name in the list of participants as well. Also, if you feel
> > like giving a talk on the topic, let's add it to the topic list.
> >
> 
> Done.
> 
> Cheers,
> Punit
> 
> > Currently I am simple checking what would be the level of interest to
> > have this topic as a LPC microconference.
> >
> > BR,
> >
> > Eduardo Valentin
> >
> >
> > [1] - http://wiki.linuxplumbersconf.org/2015:thermal
> >
> 

Re: [RFP] LPC thermal track

[Eduardo Valentin]

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Hey Srinivas,

On Mon, Mar 30, 2015 at 12:11:17PM -0700, Srinivas Pandruvada wrote:
> On Fri, 2015-03-27 at 11:47 +0000, Punit Agrawal wrote: 
> > Hi Eduardo,
> > 
> > Thanks for proposing a thermal micro-conference. It would be good to 
> > discuss the direction things are heading with regards to thermal in linux.
> > 
> > On 27/03/15 00:02, Eduardo Valentin wrote:
> > > Hello all,
> > >
> > > I've created a proposal for a thermal microconference track on the LPC
> > > 2015 [1]. The basic idea is to get thermal developers together and
> > > discuss the thermal role within the Linux environment, from kernel and
> > > userspace perspective.
> > >
> > > A initial proposal for the topics to be discussed are:
> > > . Closed loop control governors
> > > . Sensor API
> > > . Thermal class: split of temperature sensor device and thermal driver
> > > . Improvements on OF-thermal
> > > . Devfreq vs. clock cooling
> > > . Power model based policies
> > > . User space tools
> > > . User space governors
> > >
> > > If you have interest, or if you have ideas on how to improve the
> > > framework, reply to this email and add it to the wiki.
> What about
> Some enhancement in thermal zone user space I/F for user space thermal
> controllers
> - Better support for virtual temperature sensors which depends on other
> sensors. 
> - Support for Linux IIO style scale and offset in thermal zone
> temperature calculation.
> - /dev interface for pushing thermal samples instead of raw read of
> temperature to improve performances and push sample instead of pull from
> user space.

Can you please add these topics to the wiki?

Would you be able to attend LPC and give a talk about your thoughts?

BR,

Eduardo Valentin

> 
> Thanks,
> Srinivas 
> > >
> > 
> > I'd like to propose -
> > 
> > . Co-ordination among cooling-devices in the system
> > 
> > In workloads that involve multiple devices such as camera+CPUs+image 
> > singal processor or camera+video encoding, etc. often there are 
> > dependencies across multiple devices' performance states to achieve 
> > minimum acceptable performance (24fps HD encode for example). When 
> > thermally constrained it would help to have some mechanisms to 
> > co-ordinate their performance control. The power allocator governor 
> > attempts to solve some of these problems but it would be good to have a 
> > wider discussion on enabling more scenarios.
> > 
> > 
> > > Add your name in the list of participants as well. Also, if you feel
> > > like giving a talk on the topic, let's add it to the topic list.
> > >
> > 
> > Done.
> > 
> > Cheers,
> > Punit
> > 
> > > Currently I am simple checking what would be the level of interest to
> > > have this topic as a LPC microconference.
> > >
> > > BR,
> > >
> > > Eduardo Valentin
> > >
> > >
> > > [1] - http://wiki.linuxplumbersconf.org/2015:thermal
> > >
> > 
> 
> 

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Re: [RFP] LPC thermal track

[Srinivas Pandruvada]

On Mon, 2015-03-30 at 13:51 -0700, Eduardo Valentin wrote:
Hi Eduardo,

> Hey Srinivas,
> 
> On Mon, Mar 30, 2015 at 12:11:17PM -0700, Srinivas Pandruvada wrote:
> > On Fri, 2015-03-27 at 11:47 +0000, Punit Agrawal wrote: 
> > > Hi Eduardo,
> > > 
> > > Thanks for proposing a thermal micro-conference. It would be good to 
> > > discuss the direction things are heading with regards to thermal in linux.
> > > 
> > > On 27/03/15 00:02, Eduardo Valentin wrote:
> > > > Hello all,
> > > >
> > > > I've created a proposal for a thermal microconference track on the LPC
> > > > 2015 [1]. The basic idea is to get thermal developers together and
> > > > discuss the thermal role within the Linux environment, from kernel and
> > > > userspace perspective.
> > > >
> > > > A initial proposal for the topics to be discussed are:
> > > > . Closed loop control governors
> > > > . Sensor API
> > > > . Thermal class: split of temperature sensor device and thermal driver
> > > > . Improvements on OF-thermal
> > > > . Devfreq vs. clock cooling
> > > > . Power model based policies
> > > > . User space tools
> > > > . User space governors
> > > >
> > > > If you have interest, or if you have ideas on how to improve the
> > > > framework, reply to this email and add it to the wiki.
> > What about
> > Some enhancement in thermal zone user space I/F for user space thermal
> > controllers
> > - Better support for virtual temperature sensors which depends on other
> > sensors. 
> > - Support for Linux IIO style scale and offset in thermal zone
> > temperature calculation.
> > - /dev interface for pushing thermal samples instead of raw read of
> > temperature to improve performances and push sample instead of pull from
> > user space.
> 
> Can you please add these topics to the wiki?
I will. 
> 
> Would you be able to attend LPC and give a talk about your thoughts?
Yes.

Thanks,
Srinivas 
> 
> BR,
> 
> Eduardo Valentin
> 
> > 
> > Thanks,
> > Srinivas 
> > > >
> > > 
> > > I'd like to propose -
> > > 
> > > . Co-ordination among cooling-devices in the system
> > > 
> > > In workloads that involve multiple devices such as camera+CPUs+image 
> > > singal processor or camera+video encoding, etc. often there are 
> > > dependencies across multiple devices' performance states to achieve 
> > > minimum acceptable performance (24fps HD encode for example). When 
> > > thermally constrained it would help to have some mechanisms to 
> > > co-ordinate their performance control. The power allocator governor 
> > > attempts to solve some of these problems but it would be good to have a 
> > > wider discussion on enabling more scenarios.
> > > 
> > > 
> > > > Add your name in the list of participants as well. Also, if you feel
> > > > like giving a talk on the topic, let's add it to the topic list.
> > > >
> > > 
> > > Done.
> > > 
> > > Cheers,
> > > Punit
> > > 
> > > > Currently I am simple checking what would be the level of interest to
> > > > have this topic as a LPC microconference.
> > > >
> > > > BR,
> > > >
> > > > Eduardo Valentin
> > > >
> > > >
> > > > [1] - http://wiki.linuxplumbersconf.org/2015:thermal
> > > >
> > > 
> > 
> > 

Re: [RFP] LPC thermal track

[Eduardo Valentin]

Hello folks,

On Thu, Mar 26, 2015 at 08:02:49PM -0400, Eduardo Valentin wrote:
> Hello all,
>
> I've created a proposal for a thermal microconference track on the LPC
> 2015 [1]. The basic idea is to get thermal developers together and
> discuss the thermal role within the Linux environment, from kernel and
> userspace perspective.
>
> A initial proposal for the topics to be discussed are:
> . Closed loop control governors
> . Sensor API
> . Thermal class: split of temperature sensor device and thermal driver
> . Improvements on OF-thermal
> . Devfreq vs. clock cooling
> . Power model based policies
> . User space tools
> . User space governors
>
> If you have interest, or if you have ideas on how to improve the
> framework, reply to this email and add it to the wiki.
>
> Add your name in the list of participants as well. Also, if you feel
> like giving a talk on the topic, let's add it to the topic list.
>
> Currently I am simple checking what would be the level of interest to
> have this topic as a LPC microconference.

Just a reminder about the thermal micro conference.

I would like to thank the interested people who have signed up for
presenting topics and attending the proposed mc. I have updated
the wiki with the topics, organized by presenter.

However, I believe we still need extra entropy.

So, if you have interest on the topic and feel like attending the mc,
please add your name to the wiki. Also, if you want to propose a
presentation of a subject which is not listed there, let me know by
replying to this email (copy the list).

BR,

Eduardo Valentin


>
> BR,
>
> Eduardo Valentin
>
>
> [1] - http://wiki.linuxplumbersconf.org/2015:thermal

Re: [RFP] LPC thermal track

[Eduardo Valentin]

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Hello folks,

On Thu, Mar 26, 2015 at 08:02:49PM -0400, Eduardo Valentin wrote:
> Hello all,
>
> I've created a proposal for a thermal microconference track on the LPC
> 2015 [1]. The basic idea is to get thermal developers together and
> discuss the thermal role within the Linux environment, from kernel and
> userspace perspective.
>
> A initial proposal for the topics to be discussed are:
> . Closed loop control governors
> . Sensor API
> . Thermal class: split of temperature sensor device and thermal driver
> . Improvements on OF-thermal
> . Devfreq vs. clock cooling
> . Power model based policies
> . User space tools
> . User space governors
>
> If you have interest, or if you have ideas on how to improve the
> framework, reply to this email and add it to the wiki.
>
> Add your name in the list of participants as well. Also, if you feel
> like giving a talk on the topic, let's add it to the topic list.
>
> Currently I am simple checking what would be the level of interest to
> have this topic as a LPC microconference.

Just a reminder about the thermal micro conference.

I would like to thank the interested people who have signed up for
presenting topics and attending the proposed mc. I have updated
the wiki with the topics, organized by presenter.

However, I believe we still need extra entropy.

So, if you have interest on the topic and feel like attending the mc,
please add your name to the wiki. Also, if you want to propose a
presentation of a subject which is not listed there, let me know by
replying to this email (copy the list).

BR,

Eduardo Valentin


>
> BR,
>
> Eduardo Valentin
>
>
> [1] - http://wiki.linuxplumbersconf.org/2015:thermal


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Re: [RFP] LPC thermal track

[Eduardo Valentin]

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Hello all,

On Tue, Apr 28, 2015 at 10:24:15PM -0700, Eduardo Valentin wrote:
> Hello folks,
> 
> On Thu, Mar 26, 2015 at 08:02:49PM -0400, Eduardo Valentin wrote:
> > Hello all,
> >
> > I've created a proposal for a thermal microconference track on the LPC
> > 2015 [1]. The basic idea is to get thermal developers together and
> > discuss the thermal role within the Linux environment, from kernel and
> > userspace perspective.
> >
> > A initial proposal for the topics to be discussed are:
> > . Closed loop control governors
> > . Sensor API
> > . Thermal class: split of temperature sensor device and thermal driver
> > . Improvements on OF-thermal
> > . Devfreq vs. clock cooling
> > . Power model based policies
> > . User space tools
> > . User space governors
> >
> > If you have interest, or if you have ideas on how to improve the
> > framework, reply to this email and add it to the wiki.
> >
> > Add your name in the list of participants as well. Also, if you feel
> > like giving a talk on the topic, let's add it to the topic list.
> >
> > Currently I am simple checking what would be the level of interest to
> > have this topic as a LPC microconference.
> 
> Just a reminder about the thermal micro conference.
> 
> I would like to thank the interested people who have signed up for
> presenting topics and attending the proposed mc. I have updated
> the wiki with the topics, organized by presenter.
> 
> However, I believe we still need extra entropy.
> 
> So, if you have interest on the topic and feel like attending the mc,
> please add your name to the wiki. Also, if you want to propose a
> presentation of a subject which is not listed there, let me know by
> replying to this email (copy the list).
> 

Apologize for the noise. I am copying LKML this time.

> BR,
> 
> Eduardo Valentin
> 
> 
> >
> > BR,
> >
> > Eduardo Valentin
> >
> >
> > [1] - http://wiki.linuxplumbersconf.org/2015:thermal
> 



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Re: [RFP] LPC thermal track

[Eduardo Valentin]

Hello folks,

On Thu, Mar 26, 2015 at 08:02:49PM -0400, Eduardo Valentin wrote:
> Hello all,

I want to share with you that the thermal micro conference is accepted [1].
This is going to be the first time thermal is discussed in a mc in LPC!
So, thanks all for the interest and thanks the committee for the
support!

Next step is, of course, to register if you haven't yet!

I will be working on the details of the micro conference, such as
timing, etc, and will share as soon as possible. 

See you in Seattle!

BR,

Eduardo Valentin

[1] -
https://linuxplumbersconf.org/2015/thermal-microconference-accepted-into-2015-linux-plumbers-conference/

[ANNOUNCE] Report of the thermal micro-conference in LPC 2015 - Seattle, WA

[Eduardo Valentin]

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Hello,

On Thu, Mar 26, 2015 at 08:02:49PM -0400, Eduardo Valentin wrote:
> Hello all,
> 
> 

<cut>

> A initial proposal for the topics to be discussed are:
> . Closed loop control governors
> . Sensor API
> . Thermal class: split of temperature sensor device and thermal driver
> . Improvements on OF-thermal
> . Devfreq vs. clock cooling
> . Power model based policies
> . User space tools
> . User space governors
> 

I want to thank you all who was present in Linux Plumbers 2015 this year
for the thermal MC. Also, I want to thank the LPC organization to
opening up the space, infrastructure, and time slot to make the first
thermal mc within this event.

I am writing a short summary of the discussion we had during the MC
for those that were not present. You may find the MC minute note
in Etherpad [1]. You may also find the slide set of each presentation in
LPC webpage [2].

Key attendees:
- Rui Zhang
- Len Brown
- Rafael J. Wysocki
- Srinivas Pandruvada
- Kristen Accardi
- Javi Merino
- Punit Agrawal
- Kapileshwar Singh
- Lina Iyer
- Eduardo Valentin

We started with a brief overview of the subsystem. I described the
concepts involved and how they are represented in the subsystem:
thermal zones, thermal sensors, trip points, cooling devices, and
thermal governors. I also gave a snapshot of the supported SoCs. To open
the discussion for the following presentations, I introduced the current
open items. The list was restricted compared to our original proposal
(above). Therefore, the MC focused more on the sensor API, thermal zone
representation, and tools.

On the sensor API, there were several proposals. First, there is an
agreement within the community (at least those in the audience) that
there is a need to have the representation of more than one sensor per
zone. Use cases of extrapolating hotspots on package or on device
surfaces are the typical application of this needed support.

Still in the sensor API, specially what concerns the interactions with
userspace, there is also an consensus that monitoring temperature from
userspace using the thermal subsystem may be not optimal. Overhead and
latencies are the main concerns. However, we do have thermal management
solutions in userspace that needs to be supported. (open source) Examples
of them are thermald, iTux, and DPTF. The proposal to improve in this
front is to add a thermal -> iio bridge [3]. The audience also did not
presented any resistance on this proposal.

Related to the sensor API is the thermal topology representation. There
are two major proposals here. First is to have a hierarchical
representation of thermal zones. The hierarchy would be reflected in the
sysfs representation of thermal. The hierarchy is linked to have multiple
temperature sources into a single thermal zone, except that the source
could be another thermal zone. This point brings up the idea of having
aggregation functions on the temperature inputs. Examples of common
aggregation functions are: maximum temperature, moving average window,
linear extrapolation (linear coefficients). The idea would be to allow
switching the aggregation function from userspace.

The second proposal on thermal topology, on top of having hierarchical
representation, would be to also add the knowledge of which devices the
thermal zone covers. The motivation here is to have an API to get
a temperature of a device using its struct device *. This type of query
is useful while computing estimation of leakage power, for instance. We
would need to have a list of struct device * within the thermal zone device
struct. However, if you think about it, a device may also be covered
by multiple thermal zones. Therefore, we may end up with a many to many
relationship.

We also had a presentation on assertion based thermal testing. The
presented tool is able to produce automated testing using assertions
on top of tracing produced by the thermal framework. The tool has been
used to compare system behavior on the same workload across different
thermal management solutions (say, between thermal governors). The tool
has also been used to profile EAS behavior. I personally like the fact
that the building blocks we have today inside the kernel enables us to
deploy such kind of tools.

The last, but not least, discussion was around the link between thermal
and EAS. The idea is to close the loop and improve performance. Idea is
to have thermal governor (such as power allocator) to talk to the
scheduler, and use the thermal limit as a notion of capacity. However,
at this point, not much data on which clear use cases the improvement
would be seen. It would interesting to know the performance
improvements, and also, the power and thermal benefits.

I hope we keep having such opportunities to get the thermal community to
discuss the current challenges and how we can better enhance the
existing solutions.

BR,

Eduardo Valentin


[1] - https://etherpad.openstack.org/p/LPC2015_Thermal
[2] - http://linuxplumbersconf.org/2015/ocw/events/LPC2015/tracks/477
[3] - http://www.spinics.net/lists/linux-iio/msg20696.html

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