Speedup possibility in LowPtGsfElectronSeedProducer for Phase2

[swagata87]

LowPtGsfElectronSeedProducer takes 3% time in Phase2. https://cms-reco-profiling.web.cern.ch/cms-reco-profiling/circles/piechart.php?local=false&dataset=CMSSW_13_0_0_pre1%2Fel8_amd64_gcc11%2F21034.21%2Fstep3_circles&resource=time_real&colours=default&groups=reco_PhaseII&threshold=0

Currently, the way things are set up for phase2, low-pt electron only gets reconstructed in barrel. It needs more studies/effort to make it work in the endcaps. The plot below is just a eta plot of objects in the collection slimmedLowPtElectrons from DYToLL sample (PhaseIISpring22, PU=0 ).

However the code LowPtGsfElectronSeedProducer.cc, loops over all tracks, even the tracks in endcap, for Phase2, as it tries to create the tracker-driven seeds for low-pT electrons. https://github.com/cms-sw/cmssw/blob/9dccb35517a388915bae19dc88ad99d99374ace6/RecoEgamma/EgammaElectronProducers/plugins/LowPtGsfElectronSeedProducer.cc#L331-L332

It looks like, a phase-2 specific eta cut might reduce the timing. This should at least be checked.

This issue is somewhat similar to https://github.com/cms-sw/cmssw/issues/39537

[cmsbuild]

A new Issue was created by @swagata87 Swagata Mukherjee.

@Dr15Jones, @perrotta, @dpiparo, @rappoccio, @makortel, @smuzaffar can you please review it and eventually sign/assign? Thanks.

cms-bot commands are listed here

[swagata87]

assign reconstruction, upgrade

[cmsbuild]

New categories assigned: upgrade,reconstruction

@AdrianoDee,@mandrenguyen,@clacaputo,@srimanob you have been requested to review this Pull request/Issue and eventually sign? Thanks

[swagata87]

type egamma

[swagata87]

FYI @sameasy @Prasant1993 @SohamBhattacharya @bainbrid