Octave is one of the most widely used open source tools for numerical analysis and liner algebra. Our project aims to improve Octave by introducing support for GPU computing in order to speed up some ...linear algebra operations. The core of our work is a C library that executes some BLAS operations concerning vector- vector, vector matrix and matrix-matrix functions on the GPU. OpenCL functions are used to program GPU kernels, which are bound within the GNU/octave framework. We report the project implementation design and some preliminary results about performance.
The distributed data analysis workflow in CMS assumes that jobs run in a different location to where their results are finally stored. Typically the user outputs must be transferred from one site to ...another by a dedicated CMS service, AsyncStageOut. This new service is originally developed to address the inefficiency in using the CMS computing resources when transferring the analysis job outputs, synchronously, once they are produced in the job execution node to the remote site. The AsyncStageOut is designed as a thin application relying only on the NoSQL database (CouchDB) as input and data storage. It has progressed from a limited prototype to a highly adaptable service which manages and monitors the whole user files steps, namely file transfer and publication. The AsyncStageOut is integrated with the Common CMS/Atlas Analysis Framework. It foresees the management of nearly nearly 200k users' files per day of close to 1000 individual users per month with minimal delays, and providing a real time monitoring and reports to users and service operators, while being highly available. The associated data volume represents a new set of challenges in the areas of database scalability and service performance and efficiency. In this paper, we present an overview of the AsyncStageOut model and the integration strategy with the Common Analysis Framework. The motivations for using the NoSQL technology are also presented, as well as data design and the techniques used for efficient indexing and monitoring of the data. We describe deployment model for the high availability and scalability of the service. We also discuss the hardware requirements and the results achieved as they were determined by testing with actual data and realistic loads during the commissioning and the initial production phase with the Common Analysis Framework.
In 2012, 14 Italian Institutions participating LHC Experiments (10 in CMS) have won a grant from the Italian Ministry of Research (MIUR), to optimize Analysis activities and in general the ...Tier2/Tier3 infrastructure. A large range of activities is actively carried on: they cover data distribution over WAN, dynamic provisioning for both scheduled and interactive processing, design and development of tools for distributed data analysis, and tests on the porting of CMS software stack to new highly performing / low power architectures.
An Xrootd Italian Federation Boccali, T; Donvito, G; Diacono, D ...
Journal of physics. Conference series,
01/2014, Letnik:
513, Številka:
4
Journal Article
Recenzirano
Odprti dostop
The Italian community in CMS has built a geographically distributed network in which all the data stored in the Italian region are available to all the users for their everyday work. This activity ...involves at different level all the CMS centers: the Tier1 at CNAF, all the four Tier2s (Bari, Rome, Legnaro and Pisa), and few Tier3s (Trieste, Perugia, Torino, Catania, Napoli, ...). The federation uses the new network connections as provided by GARR, our NREN (National Research and Education Network), which provides a minimum of 10 Gbit/s to all the sites via the GARR-X2 project. The federation is currently based on Xrootd1 technology, and on a Redirector aimed to seamlessly connect all the sites, giving the logical view of a single entity. A special configuration has been put in place for the Tier1, CNAF, where ad-hoc Xrootd changes have been implemented in order to protect the tape system from excessive stress, by not allowing WAN connections to access tape only files, on a file-by-file basis. In order to improve the overall performance while reading files, both in terms of bandwidth and latency, a hierarchy of xrootd redirectors has been implemented. The solution implemented provides a dedicated Redirector where all the INFN sites are registered, without considering their status (T1, T2, or T3 sites). An interesting use case were able to cover via the federation are disk-less Tier3s. The caching solution allows to operate a local storage with minimal human intervention: transfers are automatically done on a single file basis, and the cache is maintained operational by automatic removal of old files.
In 2012, 14 Italian institutions participating in LHC Experiments won a grant from the Italian Ministry of Research (MIUR), with the aim of optimising analysis activities, and in general the Tier2 ...Tier3 infrastructure. We report on the activities being researched upon, on the considerable improvement in the ease of access to resources by physicists, also those with no specific computing interests. We focused on items like distributed storage federations, access to batch-like facilities, provisioning of user interfaces on demand and cloud systems. R&D on next-generation databases, distributed analysis interfaces, and new computing architectures was also carried on. The project, ending in the first months of 2016, will produce a white paper with recommendations on best practices for data-analysis support by computing centers.
Radiation hardness is a critical design concern for present and future silicon detectors in high energy physics. Tracking systems at the CERN Large Hadron Collider (LHC) are expected to operate for ...ten years and to receive fast hadron fluences equivalent to 10/sup 15/cm/sup -2/ 1-MeV neutrons. Recently, low temperature operating conditions have been suggested as a means of suppressing the negative effects of radiation damage on detector charge collection properties. To investigate this effect, simulations have been carried out using the ISE-TCAD DESSIS device simulator. The so-called "three-level model" has been used. A comprehensive analysis of the influence of the V/sub 2/, C/sub i/O/sub i/ and V/sub 2/O capture cross sections on the effective doping concentration (N/sub eff/) as a function of temperature and fluence has been carried out. The capture cross sections have been varied in the range 10/sup -18/-10/sup -12/ cm/sup 2/. The simulated results are compared with charge collection spectra obtained with 1064-nm laser pulses on devices irradiated with 23-GeV protons as a function of detector bias voltage. To validate the model, a wide range of temperature and fluence has been studied using a one-dimensional (1-D) simplified structure. Thousands of simulation results have been cross checked with the experimental data. The data between 190 K (the lower limit for simulations due to computational difficulties) and 290 K are well reproduced for all of the fluences considered. We conclude that the three-level model can be successfully used to predict irradiated detector behavior down to a temperature of at least 190 K.
Silicon detectors in particle physics experiments at the CERN Large Hadron Collider will be exposed to unprecedented levels of radiation. The principal obstacle to long-term operation in this ...environment is changes in detector effective doping concentration (Neff). We present a model of defect evolution during gamma and hadron irradiation which has been combined with Shockley–Read–Hall (SRH) statistics to predict Neff and dark current in irradiated devices. These predictions are compared with experimental results from detectors with various oxygen and carbon concentrations. In the case of gamma irradiation, the electrical characteristics are described satisfactorily by the production of divacancy–oxygen (V2O) defects. In the case of hadron irradiation, however, the experimental data cannot be explained in the conventional SRH picture. We propose a model whereby states in the terminal defect clusters exchange charge directly. This mechanism leads to a marked increase in carrier generation rate and an enhancement in the acceptor-like contribution to Neff. We conclude that only limited improvements in radiation hardness to hadrons can be achieved by altering detector impurity levels, since the changes in Neff are dominated by intrinsic defects within the terminal clusters.
In this paper we discuss an enhanced approach to the analysis of radiation-damaged silicon devices, with reference to numerical modelling implemented in a general-purpose device simulator. In ...particular, the emission and capture mechanism of deep levels are accounted for by means of Shockley–Read–Hall theory and shallow-level sensitivity to radiation is considered by means of a donor removal model. The effects produced by regions containing very high defect concentrations (referred to as “clusters”) are considered by calculating the direct charge exchange between two deep levels. The resulting analysis technique has been validated and calibrated by means of comparison with experimental measurements carried out on irradiated samples. The model is shown to provide comprehensive and accurate results for several radiation damage phenomena.
Radiation hardness is a critical design constraint for current and future generation silicon detectors, which are foreseen to undergo radiation fluences higher than 1×10
14
cm
−2 1-MeV neutron ...equivalent. Recently, low-temperature operating conditions have been suggested as an effective means to recover the negative effects of radiation damage on silicon detector collection properties. In order to investigate such an effect, simulations have been carried out using the ISE-TCAD DESSIS device simulator. The simulated results are compared with charge collection spectra obtained with 1064
nm laser pulses on devices irradiated with 23
GeV protons as a function of detector bias voltage. Thousands of simulation results have been cross-checked with the experimental data. The results obtained so far indicate that the “three-level model” can be successfully extended to predict irradiated detector behavior at least down to a temperature of 190
K.
PDF
