VLVNT Amsterdam 2003 – J. Panman 1

DAQ: comparison with an LHC experimentDAQ: comparison with an LHC experiment

J. Panman

CERN

VLVNT workshop 7 Oct 2003

Use as example CMS (slides taken from Cittolin's talk at LHCC)Take numbers floating around this week as typical performance needs

SUPERFI CI AL!

VLVNT Amsterdam 2003 – J. Panman 1

Data to shore:links per tower/string 1data rate/link 1.6 Gbits/stotal data rate 640 Gbits/s

Comparison of design parametersComparison of design parameters

Take numbers floating around this week as typical performance needsFor simplicity: use a “digitized scenario” (waveforms transmitted)

Data source:sampling frequency 200-400 Mhzsampling precision 8 bitssample length 50-100 nsNo. OMs 10000No. towers/strings 400Background rate 50-200 kHz/OM

Event organization:“Event” window length 10 mssize of data/event 800 Mb

VLVNT Amsterdam 2003 – J. Panman 1

Data to shore:links per tower/string 1data rate/link 1.6 Gbits/stotal data rate 640 Gbits/s

Comparison of design parametersComparison of design parameters

Take numbers floating around this week as typical performance needsFor simplicity: use a “digitized scenario” (waveforms transmitted)

Data source:sampling frequency 200-400 Mhzsampling precision 8 bitssample length 50-100 nsNo. OMs 10000No. towers/strings 400Background rate 50-200 kHz/OM

Event organization:“Event” window length 10 mssize of data/event 800 Mb

Data to surface:Average event size 1 MbyteNo. FED S-link64 ports 700DAQ links (2.5 Gb/s) 512+512Event fragment size 2 kBFED builders (8x8 dual) 64Technology(2004) Myrinet

Total data rate:total data rate 800 Gbits/s

CMS

VLVNT Amsterdam 2003 – J. Panman 1

CreditsCredits

slides taken from Cittolin's talk at LHCC

VLVNT Amsterdam 2003 – J. Panman 1

Front endFront end

Desktop/Servercurrent architecturePeripheral IO bus PCI:33/66 MHz x 32/64 bit100/200/400 MB/sPxx

MEM

Pxx

Pxx

Pxx

264 MB/s

GByte memoryMultiProcessor

PCI

PCI

264 MB/s

Dual PCI

1990' PCI

Pxx

Pxx

Pxx

Pxx

SIO

MEM

200X: PCI-X …

FE digitizerData from a string

DSP-like operation:filter produces time&charge from waveform assume 8 bytes to encode(reduction x3)

Data from a string Readout network

VLVNT Amsterdam 2003 – J. Panman 1

Network configurationsNetwork configurations

EVB staging by switch expansion:EVB staging by switch expansion:

FED -> FE digitizer

VLVNT Amsterdam 2003 – J. Panman 1

CMS – 2 stages: Data to surface & Readout CMS – 2 stages: Data to surface & Readout BuilderBuilder

Readout Builder (up to 8)64x64 x 2.5 Gb/s switchEvent rate 12.5 kHz

2 kByte

16 kByte

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FED Builder (64 units)8x8 x 5 Gb/s switchEvent fragments merger

VLVNT Amsterdam 2003 – J. Panman 1

CMS – DAQ staging : 2 RBs = 25 kHzCMS – DAQ staging : 2 RBs = 25 kHz

FED BuildersProgrammed to send events to two output (odd and even EvNo.)

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VLVNT Amsterdam 2003 – J. Panman 1

CMS – DAQ staging : 8 RBs = 100 kHzCMS – DAQ staging : 8 RBs = 100 kHzD

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VLVNT Amsterdam 2003 – J. Panman 1

CMS – 3-D DAQ implementations and CMS – 3-D DAQ implementations and scalingscaling

Readout Builders (x8):Lv-1 max. trigger rate 12.5 kHzRU Builder (64x64) .125 Tbit/sEvent fragment size 16 kBRU/BU systems 64Event filter power 105 SI95EVB technology (2006) Open

Data to surface:Average event size 1 MbyteNo. FED S-link64 ports 700DAQ links (2.5 Gb/s) 512+512Event fragment size 2 kBFED builders (8x8 dual) 64Technology(2004) Myrinet

VLVNT Amsterdam 2003 – J. Panman 1

Comparison of numbersComparison of numbers

Total data rate of km3 detector similar to an LHC detector after the L1 triggerNumber of data sources similar to number of FE Digitizers

Waveform filtering (if possible) reduces the data volume by factor 3Moore's law will help by factor 4-8 compared to LHC

Output rate of HLT farm in km3 (presumably) much lower than 100 Hzx1MbProbably data storage problem much smaller than LHC

HLT processing time/byte looks to be smaller than at LHC (LHC has to reject real physics events)

VLVNT Amsterdam 2003 – J. Panman 1

SummarySummary

DAQ architecture of LHC experiments can be a useful starting point for a design

Similar techniques, but probably smaller requirements

A couple of years later:profit from experienceprofit from performance/price ratio trend

At a first glance the DAQ does look feasable