SFT Activities during 2014
LS1 was an opportunity not only to upgrade detectors and accelerators but also the software used for analysis and data processing. The SFT team has worked closely throughout the year with software experts in the four LHC collaborations to prepare the software releases that will be used when data-taking resumes in 2015. SFT provides a consistent stack of >100 external software packages to the LHC experiments, the so-called LCG releases. During 2014 in total 8 of these releases have been provided and they are continuously being adapted to newer compiler versions and operating systems.
The ROOT team worked hard to include a number of important innovations in the ROOT toolkit, in particular a new C++ interpreter that is built on a new compiler technology called clang. ROOT has also been modernised to support new graphics formats in order to match the high quality standards needed for physics publications and to allow new possibilities in data visualisation. The LHC experiments' adoption of ROOT6 made great progress this year, to the point where large-scale validation is now in progress. One member of SFT, Axel Naumann, is participating actively in the ISO C++ Standards Committee and in 2014 two proposals were submitted reflecting new features that the HEP community can benefit from.
The SFT simulation team has contributed to the new yearly release 10.1 of the Geant4 simulation toolkit. The 10 series was introduced last year as the first production version providing the capability to generate events in parallel by means of multi-threading (MT). This version will be used for the next production runs by the CMS experiment. The new release includes many improvements for MT, bringing considerable savings in memory consumption. Many improvements in physics performance are also featured, such as a new tuning of the Fritiof hadronic model, revised meson production in string fragmentation and refinements to the Bertini Cascade model. Important improvements have also been introduced in the electromagnetic physics code, in particular in the multiple scattering models, g-conversion and high-energy processes.
The EU7-AIDA project comes to an end at the beginning of 2015 and SFT managed to deliver on all software project milestones (WP2). A new solids library (USolids) was developed, being an essential component of the geometry modeler, and is now included as an independent library in Geant4 10.1. Work on the geometry modeler is continuing in order to exploit vectorisation techniques (VecGeom) and initial results indicate that significant further improvements in performance can be achieved.
The popularity of CernVM file system (CernVM-FS) continued to grow within, and outside, the HEP community, with > 25 new projects using the file system for distributing their software. This brought new use-cases that were successfully addressed. Work continued to anticipate the needs of big centers in terms of storage backend, the service keeping the original source of the delivered software. In particular, support for the popular Amazon S3 service interface, offered by many large storage platforms, has been provided in a joint effort with the IT department. A hands-on workshop was organized in Helsinki in May 2014 in order to help users trying out CernVM-FS with their own applications. There has also been a full transition to the new new version of the CernVM virtual appliance. This has much smaller memory requirements and we are seeing a growing use as a production cloud and volunteer computing platform for ATLAS, ALICE and LHCb. It is now also established as a data preservation platform for CMS, ALICE and LHCb, and is one of the key technologies underpinning the recently launched OpenData project.
In the middle of 2014 SFT started to support the new FCC experiments’ software project. The group provides expertise and hands-on support for setting up the software based on the well-established Gaudi event-processing framework. A first prototype of the software is in place, and a tutorial aimed at new FCC developers was given at the FCC-ee workshop in November in Paris.
The group has also committed a big effort in pursuing a new R&D programme that studies various aspects of concurrent programming. The steadily increasing need for computing resources has prompted a sustained effort to optimise HEP software to take advantage of new CPU architectures and accelerators, such as GPUs. A new project has been launched to develop a new parallel simulation framework (GeantV) with highly optimised libraries for geometry and physics that fully exploit new hardware capabilities. The first achievement has been to show that the new geometrical navigation system can yield speedups exceeding one order of magnitude. The next goal is to simulate the full CMS detector using the GeantV prototype before the end of the year, firstly with simplified physics and sub-optimal performance. We expect to have meaningful performance figures for a full realistic application during 1Q 2015. As an important ingredient of the R&D work, two members of the group lectured at the CERN School of Computing held in Braga and the thematic CERN School of Computing held in Split. The theme of the lectures was "Software design in the multicore era" and covered various techniques in parallel programming.
The group currently hosts three PhD students who work on different aspects of the R&D programme: Oksana Shadura is researching genetic algorithms for parameter tuning and optimisation of the GeantV prototype; Daniel Funke studies parallel geometric algorithms in the context of ROOT as well as concurrency in experiment software frameworks; Felice Pantaleo is designing parallel trigger algorithms to run on heterogeneous architectures for the CMS Experiment. In the context of the EPLANET program, Felice visited the Rio de Janeiro State University for two weeks in October to give lectures on the fundamentals of parallel programming and how to efficiently program GPU devices. The group also hosted four technical students during the course of the year, who contributed greatly to the ROOT project (Cristina Cristescu and Philipp Schoppe), the GeantV prototype (Johannes de Fine Licht) and the development of a new website for the PH-DT and PH-SFT groups (Nefeli Kousi).
For more information about the SFT group you can visit the group's official website: http://ph-dep-sft.web.cern.ch/