TWiki> LHCb Web>WebPreferences>L0filtering (revision 2)EditAttachPDF

L0 Filtering

What is it?

The L0Filtering application is a simple alignment-task based filtering application which can be run from the PVSS panel, to filter data according to a certain set of L0 thresholds.

How to run the L0 filtering from the PVSS panel

Open the panel from an ui or plus machine:

ssh -Y lbgw

ssh -Y ui


Open the LHCb_Align tree (right click). If the tree is locked, take control (ask permission to the online piquet) by using the grey padlock.


The first action to perform is take the project: click on the grey open lock and choose "take"; write your name in the appropriate field and click on Reserve Alignment so that people know who to contact in case of need. Then ALLOCATE: click on the State menu and select Allocate.

Then select the activity L0 from the menu on the right of the Run Info panel.

Now you should select the run range that you want to filter.

To select the run range, click on the Choose Runs for Alignmnet button. Select the runs from the list selecting e.g. the activity BWDivision on the top left corner and click Ok.


To check the run you are interested in, it is useful to consult the run database here.

Now open the error log to monitor what is going on. On a shell, type:

errorLog LHCbA

Useful commands: Ctrl-S to block the screen, Ctrl-Q to resume, Ctrl-C to close.

You are now ready to start. From the LHCb_Align PVSS panel, click on the menu at the top and choose CONFIGURE. This can take a few minutes.

If the HLT subtree goes in ERROR state, you can open it and exclude the nodes or farms in error using the arrows in the Quick actions panel. To locate the troubling nodes, have a look at the PARTAlign tree.


Once the top tree is in state READY, you can click on Start run. Enjoy!

How it is implemented

The archtecture of the application can be seen clicking on RunInfo from LHCbA:TOP and then clicking on *View/Edit" below Architectures. On the bottom left corner select the Configuration L0.

It has a structure very similar to HLT2:


The L0App script is the basically core piece, while the rest is needed to read and store data has the names suggest. For each of these applications the corresponding .sh files (,,, can be found in /group/online/dataflow/cmtuser/OnlineDev_v5r31/Online/FarmConfig/job/.

The options files (L0Reader.opts, L0MEPInit.opts and L0Sender.opts) can be found in /group/online/dataflow/cmtuser/OnlineDev_v5r31/Online/FarmConfig/options/.

How to retrieve the data sample

Right now the files end up on the local disks of the four storerecv nodes (the same type of nodes as fast farm nodes), with one file per run on each node. From there they should probably be merged before being copied to EOS.

-- FrancescaDordei - 2016-04-01

Topic attachments
I Attachment History Action Size Date Who Comment
PNGpng align_panel.png r1 manage 82.0 K 2016-04-01 - 18:32 FrancescaDordei  
PNGpng architecture.png r1 manage 25.1 K 2016-04-01 - 18:31 FrancescaDordei  
JPEGjpg filtering.jpg r1 manage 143.7 K 2016-04-01 - 16:27 FrancescaDordei  
PNGpng hlt.png r1 manage 140.3 K 2016-04-01 - 18:37 FrancescaDordei  
PNGpng run_number.png r1 manage 29.8 K 2016-04-01 - 18:31 FrancescaDordei  
Edit | Attach | Watch | Print version | History: r3 < r2 < r1 | Backlinks | Raw View | Raw edit | More topic actions...
Topic revision: r2 - 2016-04-01 - FrancescaDordei
    • Cern Search Icon Cern Search
    • TWiki Search Icon TWiki Search
    • Google Search Icon Google Search

    LHCb All webs login

This site is powered by the TWiki collaboration platform Powered by PerlCopyright & 2008-2019 by the contributing authors. All material on this collaboration platform is the property of the contributing authors.
Ideas, requests, problems regarding TWiki? Send feedback