1. LHCb Online Meeting November 15th, 2000
Event Building Status
Niko Neufeld
LHCb Online Meeting November 15th, 2000

2. Done Evaluate AceNIC throughput performance
Implement event building in the NIC and run it between 2 PCs
Tested 1 on 1 event building over a switch (Foundry FastIron) in the CMS testbed
Fixed protocol with Readout Unit
Presented results at DAQ 2000, submitted paper to TNS, finished and submitted Mariannas thesis (let’s keep our fingers crossed for her!)
Niko NEUFELD
CERN, EP

3. Alteon Tigon 2 Features Development environment
Dual R4000-class processor running at 88 MHz
Up to 2 MB memory
GigE MAC+link-level interface
PCI interface
Development environment
GNU C cross compiler with few special features to support the hardware
Source-level remote debugger
Niko NEUFELD
CERN, EP

4. Test Setup PC/Linux CPU Mem PCI CERN Network GbE NIC Niko NEUFELD
CERN, EP

5. Performance of Alteon NIC
Can fill the wire at any given frame size (from 64 to 9000 bytes)
Can send out frames at a frequencies of up to 1.4 MHz
For frames bigger than 512 bytes more than 95% of nominal bandwidth available for data (practically 100% for >8000 Jumbo frames)
Niko NEUFELD
CERN, EP

6. NIC 2 NIC Performance
Niko NEUFELD
CERN, EP

7. Event Building Algorithm
Assembles events out of fragments from a known number of sources
Handles an adjustable amount of events concurrently (limited only by buffer space)
Implements “Implicit + Time-out Completion”
Uses “scatter/gather” capabilities of NIC’s DMA engine to concatenate the fragments into the host’s memory
Niko NEUFELD
CERN, EP

8. Algorithm ? Polling Start Procedure New fragment New event fragment NO
still in the
table
Fragment
out of time
Collect the
fragment
YES
Decrement
sources
Add new event
descriptor
Check for missing fragments
in previous events
Niko NEUFELD
CERN, EP

9. Performance NIC 2 NIC Average time per fragment 11.65 us Niko NEUFELD
CERN, EP

10. Event Building Achievements
Event building on a smart NIC at a frequency of incoming fragments of almost 100 KHz has been demonstrated
Event building at Gigabit speed for fragments bigger than ~1100 bytes
Code Optimization ongoing (9 us/frag have already been achieved)
Niko NEUFELD
CERN, EP

11. Being done Reorganisation of the software
NFS exported volume for easy plug-in in test-bed environments
Consistent use of several firmware versions
Improve debugging/monitoring tools
Add printf like capability
Niko NEUFELD
CERN, EP

12. To be done* Learn more about flow control in the Foundry switch
Do a full scale test on the CMS test stand (16 on 16)
*(hopefully before the LHCb week )
Niko NEUFELD
CERN, EP

13. GigE simulation of the Readout network
Very simple Ptolemy simulation exists
Uses Atlas GigE Base classes
Uses simple crossbar switch
Is modeled after the Myrinet simulation
To be done:
add all functional features of the existing models (throttling etc.)
Study Atlas behavioural switch models
Niko NEUFELD
CERN, EP