ROOT Parallelisation, Performance and Programming Model Meeting

Thursday 16 Feb 2017, 16:00 → 18:25 Europe/Zurich

42/R-022 (CERN)

Danilo Piparo (CERN)

CERN number: 71400 Extension: 109284483#

PRESENT: Enric, Lorenzo, Pere, Enrico, Martin, Raphael, Danilo, Philippe, Guilehrme, Jim

New Actions:
* Danilo, Enrico, Enric: decide an interface for trees on multiple files (or chains)
* Danilo: make progress on the 2D and 3D histos
* Danilo: merge PR 337 and tests
* Xavi: communicate to Guilherme the issue he had with vecore
* Guilherme: if possible, report on the status of the integration of veccore

Open Actions:

* Action Xavi: check the table at slide 12 pres 2, redo numbers only with 4 physical cores.
* Action Xavi: chunk the work in N parts with N being the number of processes.
Not yet done

* Action Xavi/Danilo: Work out the difficulty streaming the double_v.
Not yet tried

Closed Actions:

* Action Xavi: check if when receiving a tbb scheduler by, for example, a framework, the system should not touch it, even if the number of subscribers go to zero.
Done

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Topics for discussion:

- Integration of PR 337
-> We will integrate PR 337

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Templight:
o A clang plugin to get a profile of the compilation process: tools to parse the output are also provided (eg to get out a dot file)
 - In reality the tool is not as polished as promised - needed to produce a script to dump template instantiations ordered by time needed
o Template instantiations is only half of the time: perhaps other areas can be looked at but we do not know yet where to look
o To conlude, we believe it's a very useful tool even though it's not really drop-in yet (in contact with the author to provide our feedback)
o This work produced three PRs which have been integrated in ROOT which reduced the time needed to run the tutorials by a factor of 2 (tdf001 went from 14s to 6.5s).
o Suggestion: mix runtime and compiletime perhaps can be of help? This is a first step towards expression of cuts as simple strings to be jitted.

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 Round table:
 - Enric
    * access to CMS files as collaborators. Enric and Enrico do not yet have access.

- Lorenzo & Guilherme & Philippe:
    * VecCore is already in github - we should be able to pick veccore as an external
    * Guilherme is looking into the integration of veccore in ROOT with the way in which other externals are included
    * It is understood that part of the integration is the ability to get programmatically within ROOT the type of backend used

16:00 → 16:10 Experience with Templight

Speaker: Enrico Guiraud (CERN, University of Oldenburg (DE))

Templight.pdf

16:10 → 16:20 Integration of TPoolManager in the master branch (PR 337)

Speakers: Danilo Piparo (CERN), Xavier Valls Pla (University Jaume I (ES))

16:20 → 17:00 Round table