Re: [Starpu-devel] Fwd: Strong interest in contributions and integrations

[Andra Hugo <andra.hugo@inria.fr>]

Hi Fangli,

I looked into the code you provided and I have a few suggestions/questions. I 
will separate them in 2 parts. Let me know if it makes sense and if I can 
help with anything.

A. Code reviewing

1. Do you measure energy or power? Maybe the field names don't match 
properly(you store the energy value in the power field).
2. The task already has a structure called profiling_info that has different 
fields (start_time, submit_time, etc.), no need to add one per job
3. We have a source file with some general functions used by all the drivers 
driver_common.c, here we update all the profiling information, and it would 
be a more appropriate place to update the energy and avoid code replication.
4. It would be good to have a configure option that activates this 
measurements when the user requires them
5. It would be maybe better to integrate the code of ex_starpu_ini in 
starpu_profiling_init. I am however a little bit worried about interfering 
with the application's cmd line parameters. We usually use env variables for 
runtime options for starpu.
6. It might be unnecessary overhead to count all the sockets at each time you 
measure the power, they won't change their number at runtime (I don't think 
starpu deals with any fault tolerance problems). 
7. In starpu_ex.c there are some calls to sleep, are they really necessary?

B. Performance

8. Do you have some measurements or a paper that shows the overhead of your 
approach? The client-server communication seams a lot of overhead added 
exactly when we pop tasks which is the most performance sensitive part of 
starpu.

9. It seams that you measure the power of all CPU cores and GPUs after the 
execution of each task (ex_starpu_get_power(j->ex_start_ts, j->ex_end_ts, 
ALL_POWER))). Am I correct? How does this work for a parallel application, 
when anther processor executes another task?

10. This is more like a suggestion: In order to monitor the processors you 
create a set of threads to take care of this. StarPU also has its own set of 
threads. Leaving the OS deal with the context switch might affect 
performance. Did you consider maybe using starpu's threads instead?  I 
understand that your approach client server is definitely a better software 
engineering solution, and it can then be easily integrated in any software 
without modifying the code, but the overhead might be significant. 

That's all I can see for now. Please let me know if you have any questions or 
if I can help in any way. 

Best,
Andra

----- Mail original -----
> De: "Fangli Pi" <hpcfapix@hlrs.de>
> À: starpu-devel@lists.gforge.inria.fr
> Cc: "Dennis Hoppe" <dennis.hoppe@hlrs.de>, "Dmitry Khabi" <khabi@hlrs.de>, 
> "Michael Gienger" <gienger@hlrs.de>
> Envoyé: Lundi 9 Mai 2016 12:15:03
> Objet: [Starpu-devel] Fwd: Strong interest in contributions and       
> integrations
> 
> Dear StarPU devel-group,
> 
> Sorry for bothering you again with my mail sent two weeks ago.
> 
> Being afraid that there will be delays due to mail barriers or holidays
> during these two weeks, I would here restate my deep interest in
> contributing in StarPU by our project team.
> 
> In these two weeks we have succeed in integrating the energy measurements in
> StarPU (version 1.2.0rc5) for cpu drivers (first step towards the
> integration). Changes based on StarPU source can be found in the following
> link:
> http://gitlab.excess-project.eu/hpcfapix/starpu-ex-1-2-0rc5.git
> 
> We are now keeping the development private and it would be grateful to get
> your permission to make it public after all development is done. It is still
> of great interest by our side to merge the extension into StarPU and
> hopefully it would also be an usable feature for StarPU.
> 
> Sincerely looking forward to your reply.
> 
> Best regards,
> Fangli Pi
> 
> ----- Forwarded Message -----
> From: "Fangli Pi" <hpcfapix@hlrs.de>
> To: "starpu-devel" <starpu-devel@lists.gforge.inria.fr>
> Cc: "Michael Gienger" <gienger@hlrs.de>, "Dennis Hoppe"
> <dennis.hoppe@hlrs.de>, "Dmitry Khabi" <khabi@hlrs.de>
> Sent: Monday, April 25, 2016 10:27:27 AM
> Subject: Strong interest in contributions and integrations
> 
> Dear StarPU devel-group,
> 
> I am now working on an EU project (EXCESS, http://excess-project.eu/) using
> StarPU as a runtime system. For the project's concentration on
> energy-efficient computation, we have tried to extend StarPU power model to
> retrieve energy and power measurements from one monitoring framework,
> developed by our team.
> 
> Following is the link of our StarPU power extension, including the source
> code, some examples and a basic introduction.
> https://github.com/excess-project/starpu-energy-aware-extension.git
> 
> As we are currently thinking about an integration with StarPU, it would be
> very beneficial to get your professional opinions and relevant supports upon
> the aspect of StarPU.
> 
> Looking forward to your reply and a possible cooperation in the future.
> 
> Best regards,
> Fangli Pi
> 
> --
> High Performance Computing Center (HLRS)
> University of Stuttgart
> Nobelstr. 19
> D-70569 Stuttgart, Germany
> 
> phone: ++49-711-685-60442
> --
> High Performance Computing Center (HLRS)
> University of Stuttgart
> Nobelstr. 19
> D-70569 Stuttgart, Germany
> 
> phone: ++49-711-685-60442
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