Online Reconstruction

Data Flow

The online reconstruction requires a dedicated data flow because it runs on its own computer (apart from the decoder) and needs a large part of the data (i.e. hit info) in semi-real time (i.e. 1-2 minutes).

We are going to adopt the following data-flow scheme to begin with. We plan to measure the performance of this scheme to design the next version.

[Main-DAQ decoder] --(Output per spill)--> [ORI file]
 |                                           ^
 |(Record the status of each OR file)        |
 V                                           |
[ORI/ORO-file status in SQLite DB]           +---------------------+
 ^                         ^                                       |
 |(Query every 10 seconds) |(Record the status of each ORO file)   |(Read)
 |                         |                                       |
[Shell script to find new files] --(Launch per ORI file)--> [CPU/GPU OR program]
                                                             |
                                                             |(Output)
                                                             V
                                                            [ORO file]
                                                             ^
                                                             |(Read and draw)
                                                             |
[Various monitoring programs:  OnlMon Viewer, OR Monitor, etc.]

• "Online Reconstruction Input (ORI) file" = ROOT file containing SRawEvent objects in TTree. All ORI files are stored under /data2/e1039/online/sraw. The /data2 directory is accessible on all servers as mounted via NFS.
• Status of each OR file = "open", "update" and "close".
• "Online-Reconstruction Output (ORO) file" = ROOT file containing SRecEvent and Tracklet objects in TTree. All ORO files are stored under /data2/e1039/online/srec.
• All monitor programs read ORO file to show plots/values.

Reconstruction Program on Multi-CPU

t.b.w.?

Reconstruction Program on GPU

t.b.w.?