1. R.Divià, CERN/ALICE 1 ALICE off-line week, CERN, 9 September 2002 DAQ-HLT software interface

2. R.Divià, CERN/ALICE 2 ALICE off-line week, CERN, 9 September 2002 DAQ-HLT components LDC/FEP DAQ Network GDC Mass Storage Servers RORC DDL Detector readout electronics ~ 430 ~ 290 ~ 500 ports ~ 40 DDL DIU DDL SIU HLT Network HLT node ~ 540 ports ~ 250

3. R.Divià, CERN/ALICE 3 ALICE off-line week, CERN, 9 September 2002 Goals Provide a mechanism to: Provide a mechanism to: u allow efficient resource sharing between DAQ and HLT u smooth transition between DAQ only and DAQ-HLT modes modes u transfer events DAQ  HLT with minimum overhead u give HLT access to the data u grant the HLT the capability to: m discard (part(s) of) an event m replace (part(s) of) an event m insert new data block(s)

4. R.Divià, CERN/ALICE 4 ALICE off-line week, CERN, 9 September 2002 DAQ-HLT modes u Local: m LDC: local processing and decision  operate on data: discard/add/replace/compress m GDC: local processing and decision  operate on data: discard/add/replace/compress u Global LDC m global decision at LDC level m reject/accept full event u Global LDC & GDC m global decision at LDC level m reject/accept full or partial event u Global LDC-HLT Farm-GDC m global decision by the HLT Farm m reject/accept full or partial event

5. R.Divià, CERN/ALICE 5 ALICE off-line week, CERN, 9 September 2002 Local LDC LDCreadoutrecorder Raw DATA pool GDCDDL HLT-RORC hltAgent HLT DATA pool

6. R.Divià, CERN/ALICE 6 ALICE off-line week, CERN, 9 September 2002 Local LDC u Independent from all other levels u Infrastructure ready: m initialization and control of HLT-RORC m synchronization:  between DATE processes and hltAgent  within DATE framework (start/stop/reset/abort) m notification and transfer of events m allocation and run-time handling of memory banks m buffer manager u Zero extra network traffic & latencies u All tested OK

7. R.Divià, CERN/ALICE 7 ALICE off-line week, CERN, 9 September 2002 Local GDC GDCEventbuilder Raw DATA pool LDC HLT DATA pool hltAgent

8. R.Divià, CERN/ALICE 8 ALICE off-line week, CERN, 9 September 2002 Local GDC u Independent from all other levels u Infrastructure ready: m synchronization:  between DATE processes and hltAgent  within DATE framework (start/stop/reset/abort) m notification and transfer of events m allocation and run-time handling of memory banks m buffer manager u Recording library ready (synchronous & asynchronous) u All tested and validated @ ALICE Data Challenge IV

9. R.Divià, CERN/ALICE 9 ALICE off-line week, CERN, 9 September 2002 Global LDC LDCreadoutrecorderGDCDDL hltAgent readoutrecorder DDL hltAgent readoutrecorder DDL hltAgent readoutrecorder DDL hltAgent

10. R.Divià, CERN/ALICE 10 ALICE off-line week, CERN, 9 September 2002 Global LDC u Super-set of local LDC level m see support and status as for local LDC level u Inter-LDC hooks to be implemented m synchronization m communication u Synchronization needed on all LDCs m even the LDCs not participating to the HLT decision u Extra network latencies

11. R.Divià, CERN/ALICE 11 ALICE off-line week, CERN, 9 September 2002 Global LDC/GDC LDCreadoutrecorderGDCDDL hltAgent readoutrecorder DDL hltAgent readoutrecorder DDL hltAgent readoutrecorder DDL hltAgent

12. R.Divià, CERN/ALICE 12 ALICE off-line week, CERN, 9 September 2002 Global LDC/GDC u Super-set of global LDC level m see support and status as for local LDC level m see support and status as for global LDC level u Some LDC-to-GDC hooks to be implemented m protocol needed to accept/reject & define ROI u Extra network and protocol latencies at different levels m between LDCs m LDCs to GDC u Big impact on the event builder

13. R.Divià, CERN/ALICE 13 ALICE off-line week, CERN, 9 September 2002 Global LDC-HLT Farm-GDC LDCreadoutrecorderGDCDDL hltAgent readoutrecorder DDL hltAgent readoutrecorder DDL hltAgent readoutrecorder DDL hltAgent HLT Farm

14. R.Divià, CERN/ALICE 14 ALICE off-line week, CERN, 9 September 2002 Global LDC-HLT Farm-GDC u Super-set of global LDC/GDC level m see support and status as for local LDC level m see support and status as for global LDC level m see support and status as for global LDC/GDC level u Data transfer HLT Farm-to-GDC ready m use standard DATE recording library u HLT Farm-to-GDC hooks to be defined m protocol needed to accept/reject & define ROI u Extra network and protocol latencies u Big impact on the event builder

15. R.Divià, CERN/ALICE 15 ALICE off-line week, CERN, 9 September 2002 Food for thoughts u During the ALICE Data Challenge IV the event builders already accepted 1.8 GB/s sustained m Flat data pattern to saturate the network m Network & PC technologies from 2001 m Reduced set of LDCs (40) m Realistic set of GDCs (38)  one CPU unused (on dual-processor machines) u Global LDC vs. Local GDC: where is the cross-over?