Worldwide event filter processing for calibration

1
Worldwide event filterprocessing for calibration

• Calorimeter Calibration Workshop
• Sander Klous
• September 2006

2
Long existing idea remote computing 2004
Copenhagen Edmonton Krakow Manchester
Remote Event Processing Farms
Packet Switched WAN GEANT
lightpath
Bdlg. 513
The Magni Cluster

• Bob Dobinson, Krzysztof Korcyl, Catalin Meirosu,
  John Renner-Hansen and Jim Pinfold, Richard
  Hughes-Jones

3
Dataflow detail
Remote farm
4
StreamTag scenarios 2006
Remote
From LVL1
LVL2
SFO
RoiB
Ros/Robin
pRos
Stream selection
Add to StreamTag1
EFD
L2sv
Input
Create RoutingTag
Routing
DFM
B
ExtPT
L2pu
SFI (partially) build
Routing
Add to RoutingTag
Create StreamTag
D
C
Trash
ExtPT

• ATL-DQ-ES-0076
• In preparation
• See Sushkov presentation

Add to StreamTag2
Duplicating
Output
Output
Stripping
5
Combining the two concepts

• Streaming/routing allows to prioritize the data
• E.g. calibration events handled by remote farms

No file I/O
Bypass
6
Advantages of this approach

• Technical
• Simpler, less problems with QoS of remote farms
• Avoid processing bottleneck in Event Filter
• Avoid File I/O bottleneck in SFOs (320 MB/s)
• New bottleneck network limitation, but
• Already network capacity exceeds local storage
  and processing
• Network bandwidth grows much faster than I/O or
  CPU
• Organizational
• Complies with policy of TDAQ and Streaming WG
• Calibration events are allowed to be processed on
  remote farms
• Calibration events are allowed to overlap with
  physics events

7
Use cases

• Online detector calibration
• Access to offline compute power for online
  calibration
• No compute power available in the pit
• No space left to put extra compute power in the
  pit
• Testing of new and/or more complicated
  calibration triggers
• Wild ideas can be tested in parallel to standard
  HLT operation
• My personal favorite Jet Energy Scale
  calibration with fully hadronic ttbar events
  (http//www.nikhef.nl/grid/trigger/calibration.php
  ).

8
Dreaming about a better future

• Increasing the SFI event building rate