1

Trigger input to FFReq

2

Specific Issues for Trigger• The HLT trigger reconstruction is a bit different from the

offline reconstruction:– The trigger uses predominantly partial event reconstruction– For most of events we do as little reco. as possible to reject the

event – To save bandwidth and CPU, reconstruction is with RoI

– this can be naturally turned into parallel processing of RoIs within an event

– Latency is important as well as through-put – The HLT performs several hundred small reconstructions per event

– for every step of every trigger chain• In consequence it may be suitable for HLT to process events

using parallel code at least we should try it

3

Framework Requirements - 1• Framework must create & configure algorithms, tools and services based on

configuration information

Mapping of existing online<->offline FSM• Configure( TDAQ Config Object)

– Create AppMgr– AppMgr->configure()– AppMgr->initialize()– Assign EventLoopMgr(s) to threads

• Unconfigure()– AppMgr->finalize()– AppMgr->terminate()

• prepareForRun( int runNumber ) :– Fire “begin run incident” for every EventLoopMgr– Load run dependent (calibration/conditions) data

• Process(RobFragment* lvl1Result, RobFragment*& lvl2Result, bool& eventDecision)– EventLoopMgr->executeEvent((void*)Lvl1Result)– EventLoopMgr->Lvl2Result(vector<int>& l2resultData, vector<int>& status)

Trigger: Menu defines chains of algorithms, their parameters and their input & outputOnline: config. from DB; Offline: DB, XML or python

Offline:jobOptions define algorithms & their parameters

• Framework must implement a Finite State Model i.e. creation, configuration, initialisation, execution, finalization, termination

This state model must map onto online DAQ states (configure, unconfigure, prepareForRun, Process)

4

Differences between Trigger and Offline ProcessingI/P: 100 kHz Event Rate

O/P: 1 kHz Event Rate

Trigger provides rejection=> Full trigger processing for only 1 in 100 events Þ Different steps take very different

amounts of time ~10ms->~few secÞ Different events take very different

amounts of time ~10ms->~few sec

Event1 2 3 4 5…

Step 1

2 3

4 5

6 7 8 9 10

Trigger

Offline

Framework(steering) must support early termination of event processing after a processing step

√

5

Framework Requirements - 2• Framework must provide configuration information at the start of a job and

provide for updates at the start of a new run and during the run.• The framework must support parallel processing of different events requiring

different conditions info.

Online:Whole conditions info loaded at start of runUpdates during run at lumi-block boundary (subset of folders=>small size)

Offline:Updates at any time

6

Trigger Configuration• Trigger configuration defines:

– chains of algorithms– Properties of the algorithms– The input and output from each algorithm

7

Framework and HLT Steering

Current HLT Steering:• Seen from athena: the HLT Steering is an algorithm• Seen from the perspective of the trigger the HLT Steering has many of the properties of a frameworkQuestions: What commonality between HLT steering and New Framework Scheduler?What additional requirements for framework/scheduler to provide HLT Steering functionality?What additional trigger-specific functionality that must be provided on top of Framework

HLT Steering:• Creates & configures chains of

algorithms• Executes algorithm chains in a

data-driven • Chains process Regions of

Interest• Decides whether chain

execution should terminate (reject event) or continue until event accepted

HLT Navigation:• Input & reconstructed objects

attached to Trigger Element• Collects reco. objects associated

to RoI

8

Requirements for Trigger Framework• Supports reconstruction in RoI• Supports parallel processing of RoI• Provides algorithms with sub-set of reconstructed objects for RoI• Supports early termination of processing (event rejection)

9

Reconstruction• Currently

• Future?

Trigger• Partial Event Reconstruction• Independent reconstruction in RoI

Offline:• Full reconstruction• Full event

Trigger & Offline• Regions of Reconstruction?• Define “windows” in event around

interesting features (e.g. eta-phi region or road).

10

Reference Material

11

Requirements & design of Current (Run-1) HLT Steering

• ATL-COM-DAQ-2006-023 (ATL-DH-EN-0010)

12

F

S

S

S

F?

S

F,S

F,S

F,S

S

2006 Requirement Applicability to new framework

13

F

F,S

F,S

F,S

F,S

F,S

F,S

F,S

S

14

F

F,S

F

FF

S

S

obsolete

F

F

F

15

F

F

F

F

F

S

F

S

FFReq Mandate• 1. Summarise the requirements from both HLT and reconstruction for• configuring, scheduling and monitoring algorithms, and other related• functionality that is felt to be relevant.• These may be documented in old documents that need checking for• current relevance and completeness, or they may need to be reverse• engineered using the skill and experience of the group.

• 2. Consider how these might be accommodated in a *common* framework• that supports concurrency and helps to achieve high throughput on• many-core computers, such as the GaudiHive prototype.

• 3. In particular, consider how to minimise the need for extensions or• layers to the framework specific to one or other use case, with the• aim of making it straightforward to write algorithms to work well in• both use cases.

• 4. Converge on the union of the HLT and reconstruction requirements• for a future framework, and an analysis of the technical feasibility• of satisfying them with a single common framework.

• 5. The study group is encouraged to think beyond current• implementations, recognising that some decisions made a long time ago• and in the context of the Gaudi framework may not be applicable in the• future.

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