Filippo Costa ALICE DAQ ALICE DAQ future detector readout October 29, 2012 CERN.
Overview of DAQ at CERN experiments
description
Transcript of Overview of DAQ at CERN experiments
![Page 1: Overview of DAQ at CERN experiments](https://reader036.fdocuments.us/reader036/viewer/2022062410/56815977550346895dc6b992/html5/thumbnails/1.jpg)
Overview of DAQ at CERN experiments
E.Radicioni, INFN -20050901 - MICE Daq and
Controls Workshop
![Page 2: Overview of DAQ at CERN experiments](https://reader036.fdocuments.us/reader036/viewer/2022062410/56815977550346895dc6b992/html5/thumbnails/2.jpg)
Overview
• DAQ architectures• Implementations• Software and tools
![Page 3: Overview of DAQ at CERN experiments](https://reader036.fdocuments.us/reader036/viewer/2022062410/56815977550346895dc6b992/html5/thumbnails/3.jpg)
Some basic parameters
![Page 4: Overview of DAQ at CERN experiments](https://reader036.fdocuments.us/reader036/viewer/2022062410/56815977550346895dc6b992/html5/thumbnails/4.jpg)
Overall architecture
• This is LHCb, but at this level they all look the same.
• Buffering on the FE, waiting for LV-0/1 decision
• Building network
• HLT filtering before storage.
![Page 5: Overview of DAQ at CERN experiments](https://reader036.fdocuments.us/reader036/viewer/2022062410/56815977550346895dc6b992/html5/thumbnails/5.jpg)
This is already a standard PC with Ethernet
… but they DO differ right after the FEs
ALICECMS
This is the entry point into a customized Myrinet network
1 EVB level2 EVB levels
![Page 6: Overview of DAQ at CERN experiments](https://reader036.fdocuments.us/reader036/viewer/2022062410/56815977550346895dc6b992/html5/thumbnails/6.jpg)
DAQ: taking care of Data Flow
• Building• Processing• Storage• Get the data to some network as fast as
possible• Custom VS standard network technology• CMS & Alice as extremes
– The others are in between
![Page 7: Overview of DAQ at CERN experiments](https://reader036.fdocuments.us/reader036/viewer/2022062410/56815977550346895dc6b992/html5/thumbnails/7.jpg)
CMS approach• Only 1 hardware trigger, do the rest in HLT high DAQ bandwidth.
– Flexible trigger, but rigid DAQ. Also partitioning less flexible.• Barrel-shifter approach: deterministic but rigid, customized network• 2-stage building
![Page 8: Overview of DAQ at CERN experiments](https://reader036.fdocuments.us/reader036/viewer/2022062410/56815977550346895dc6b992/html5/thumbnails/8.jpg)
ALICE approach• HLT embedded in the DAQ• More than one hardware trigger not straightforward to change trigger
– But DAQ can be very flexible with standard technology. Easy to partition down to the level of the single front-end
• HLT / Monitoring
![Page 9: Overview of DAQ at CERN experiments](https://reader036.fdocuments.us/reader036/viewer/2022062410/56815977550346895dc6b992/html5/thumbnails/9.jpg)
Alice HLT
![Page 10: Overview of DAQ at CERN experiments](https://reader036.fdocuments.us/reader036/viewer/2022062410/56815977550346895dc6b992/html5/thumbnails/10.jpg)
List of DAQ functions (one may expect)
• Run control (state machine) with GUI– Configure DAQ topology– Select trigger– Start/stop (by user or by DCS)– Communicate status to DCS
• Partitioning. Its importance is never stressed enough.• Minimal set of hardware access libraries (VME, USB, S-
LINK), and ready-to-use methods to initialize interfaces.
• Data flow– Push (or pull …) data from FE to Storage via (one or more)
layer of Event-Building• DAQ performance check with GUI• Data quality monitoring (or framework to do it)
– GUI most likely external• Logging (DAQ-generated messages) with GUI to
select/analyze logs
![Page 11: Overview of DAQ at CERN experiments](https://reader036.fdocuments.us/reader036/viewer/2022062410/56815977550346895dc6b992/html5/thumbnails/11.jpg)
• What can you expect to be able to use out of these systems?
• MICE test beam system• Who’s providing the best “test beam”
system?– Reduced scale, but keeping rich
functionality– And software already available– Not only framework, but also ready-to-use
applications and GUIs.
![Page 12: Overview of DAQ at CERN experiments](https://reader036.fdocuments.us/reader036/viewer/2022062410/56815977550346895dc6b992/html5/thumbnails/12.jpg)
All experiments more or less implement this:
Main data flow~ 10-100 KHz
Spying data subset for monitoring
Also good for test beams, ~ 1KHz
Support for test beams vary from one experiment to the other, from barebone system (just framework) to full-fledged support
![Page 13: Overview of DAQ at CERN experiments](https://reader036.fdocuments.us/reader036/viewer/2022062410/56815977550346895dc6b992/html5/thumbnails/13.jpg)
• CMS: public-domain framework, called xdaq: http://xdaq.web.cern.ch/xdaq/ Just framework (data and message passing, event-builder). For the rest, you are on your own.
• ALICE tends to support its detector teams with a full set of DAQ tools– Partitioning– Data transport– Monitoring– Logging
• ATLAS similar to ALICE in this respect– However, at the times of HARP construction it was
not yet ready for release to (external) groups.
![Page 14: Overview of DAQ at CERN experiments](https://reader036.fdocuments.us/reader036/viewer/2022062410/56815977550346895dc6b992/html5/thumbnails/14.jpg)
Readout
•Clear separation of readout and recording functions
•Readout high-priority (or read-time), recorder low priority (quasi-async)
•Large memory buffer to accommodate for fluctuations
![Page 15: Overview of DAQ at CERN experiments](https://reader036.fdocuments.us/reader036/viewer/2022062410/56815977550346895dc6b992/html5/thumbnails/15.jpg)
User-provided functions
A clear, simple way for the user to initialize and read out its own hardware
![Page 16: Overview of DAQ at CERN experiments](https://reader036.fdocuments.us/reader036/viewer/2022062410/56815977550346895dc6b992/html5/thumbnails/16.jpg)
Event builder• Running on a standard PC• Able to perform, at the same time:
– Global or partial on-demand building– EVB strategies to be matched to trigger
configurations– Event consistency checks– Recording to disk– Serving events to subscribers (i.e.
monitoring)• With basic data selections• Possibly with multi-staging after the event-building
![Page 17: Overview of DAQ at CERN experiments](https://reader036.fdocuments.us/reader036/viewer/2022062410/56815977550346895dc6b992/html5/thumbnails/17.jpg)
Event format: headers and payloads, one payload per front-end
Precise time-stamping, numbering and Ids on headers of each payload
![Page 18: Overview of DAQ at CERN experiments](https://reader036.fdocuments.us/reader036/viewer/2022062410/56815977550346895dc6b992/html5/thumbnails/18.jpg)
Ready-to-use GUIs
Run control should be implemented as a state machine for proper handling of state change
Configure and partition
Set run parameters and connect
Select active processes and start them
Start/stop
![Page 19: Overview of DAQ at CERN experiments](https://reader036.fdocuments.us/reader036/viewer/2022062410/56815977550346895dc6b992/html5/thumbnails/19.jpg)
Run-control
One run-control agent per DAQ “actor”
![Page 20: Overview of DAQ at CERN experiments](https://reader036.fdocuments.us/reader036/viewer/2022062410/56815977550346895dc6b992/html5/thumbnails/20.jpg)
Run-control partitioning
Warning: to take advantage of DAQ partitioning, also TRIGGER has to support partition …
Requirement to TRIGGER system
![Page 21: Overview of DAQ at CERN experiments](https://reader036.fdocuments.us/reader036/viewer/2022062410/56815977550346895dc6b992/html5/thumbnails/21.jpg)
Logging
•Informative logging with an effective user interface
•Log filtering and archiving
•Run statistic collection and reporting also useful
![Page 22: Overview of DAQ at CERN experiments](https://reader036.fdocuments.us/reader036/viewer/2022062410/56815977550346895dc6b992/html5/thumbnails/22.jpg)
Monitoring
•A ready-to-use monitoring architecture
•With a monitoring library as a software interface
•Depending on DAQ systems, a global monitoring GUI (to be extended for specific needs) might be available already
![Page 23: Overview of DAQ at CERN experiments](https://reader036.fdocuments.us/reader036/viewer/2022062410/56815977550346895dc6b992/html5/thumbnails/23.jpg)
Recent trends: the ECS
•An overall controller of the complete status of the experiment, including DCS
•Partitionable state machine
•Configuration databases
•Usually interfaced to PVSS, but EPICS should also be possible
![Page 24: Overview of DAQ at CERN experiments](https://reader036.fdocuments.us/reader036/viewer/2022062410/56815977550346895dc6b992/html5/thumbnails/24.jpg)
Conclusions: never underestimate …
• Users are not experts: provide them the tools to work and to report problems effectively.
• Flexible partitioning.• Event-building with accurate fragment
alignment and validity checks, state reporting and reliability.
• Redundancy / fault tolerance• A proper run-control with state-machine
– And simplifying to the users the tasks of Partition, Configure, Trigger selection, Start, Stop
• A good monitoring framework, with clear-cut separation between DAQ services and monitoring clients
• Extensive and informative logging• GUIs