sPHENIX tracking discussion

["Osborn, Joe" <osbornjd AT ornl.gov>]

Hi Christof,

Thanks for the slides, this is a helpful summary of our discussion on Monday. A few scattered thoughts below:

It looks like the most "invasive" change will be moving the clusterkey to to a short int instead of a uint64 with the indices separated by hitsetkey (or surface/detector element I assume is the intent here). We have a lot of places in the seeding where we look up cluster keys from the cluster container which will be affected by this.

By the way, I think Acts also uses vectors over any other storage container for both speed+memory improvements. Generally their containers are accessed solely by index, so it requires careful bookkeeping but I guess this is also your suggestion for the longer term to move away from maps.

Regarding the field map, I learned that the way Acts stores the field values is simply in a vector of double value Eigen3 vectors. These are then accessed by (again, an indexed) cell value when the magnetic field element is called in e.g. the fitter. Discussing with Andi we came to the conclusion it would be a useful feature to have float vs. double option. We load the magnetic field into Acts at the very beginning of the clustering when doing the geometry building. Out of curiosity, do we know to what precision the actual magnetic field mapping will have (e.g. will it really have double precision)?

I think my studies over the last couple of days indicate that we won't be able to do much better on the silicon seed purity in AuAu than what we have now, as the seeds that are produced are not obvious duplicates and as such we need to treat them as real tracklet possibilities. So I can work on creating the track seed object and corresponding SvtxTrack changes since you have already been working on the cluster parameterization.

Joe

---------------------------

Joe Osborn, Ph.D.

Associate Research Scientist

Oak Ridge National Laboratory

osbornjd AT ornl.gov

(859)-433-8738

---

From: sPHENIX-tracking-l <sphenix-tracking-l-bounces AT lists.bnl.gov> on behalf of Christof Roland via sPHENIX-tracking-l <sphenix-tracking-l AT lists.bnl.gov>
Sent: Tuesday, April 5, 2022 3:32 PM
To: Hugo Pereira Da Costa via sPHENIX-tracking-l <sphenix-tracking-l AT lists.bnl.gov>
Subject: [EXTERNAL] [Sphenix-tracking-l] roadmap and todo list for memory reduction

 

Hi Tony and Joe,

as promised yesterday I put together a few slides listing the items we need to change
in the software to implement the change in strategy we talked about yesterday.
Please have a look and comment.

Cheers

     Christof

_______________________________________________
sPHENIX-tracking-l mailing list
sPHENIX-tracking-l AT lists.bnl.gov
hxxps://lists.bnl.gov/mailman/listinfo/sphenix-tracking-l