Biweekly meeting: C++ Modules in ROOT

Oksana Shadura (University of Nebraska Lincoln (US)), Vasil Georgiev Vasilev (Institute for Advanced Physical Studies (BG))
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ROOT Team Meeting
Axel Naumann
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Attendance: Axel, David, Oksana, Vassil

Vassil: Added a few performance fixes wrt runtime. Some workflows are 30% faster. Investigating . The memory footprint is a little high but expected. Oksana has more details. In the meantime I have send Richard Smith (from Google) some information and maybe he has some directions for us to optimize. I resumed working on the global module index. Preparing for the release.

Oksana: Preparing for the release. Busy with a lot of tiny things. There was an issue with the installation of modules. For the next release we will have a better way of doing things. We received an email v6.20 vs v6.18 from Alice. The results showed 200Mb more for v6.20. I tried to remeasure the numbers in the context of CMSSW. For v6.18 we have 0 pcms (as expected) for v6.20 we have 95 pcms and the ongoing work is around 200 in module-aware CMSSW.  CMSSW with 6.18 vs v6.20 consumes 135mb more for 100 modules. In rootbench (we don't build with -Dall=On) we have 75 modules the overhead is around 40 Mb. The overhead seems to depend on the N of modules we are loading. I will generate memory flamegraphs for ROOT with 75 modules and 100 modules. Alice's 200Mb overhead should be ~80. It should not be that high. We should ask Peter for clarification. I am working on the CLHEP modulemap.

David: We have compilation errors in the CMSSW IB in DataFormats/BTauReco: I have started an igprof job for measuring the ROOT startup.

Axel: Spent couple of hours with Philippe discussing the diagnostic client with recursive parsing: . We will come up in with a temporary patch in local clang. I am hunting down a few non-module-related issues.


AOB: Next meeting in two weeks.

There are minutes attached to this event. Show them.
    • 14:00 14:30
      Updates 30m
      Speakers: Oksana Shadura (University of Nebraska Lincoln (US)), Vasil Georgiev Vasilev (Institute for Advanced Physical Studies (BG))
    • 14:30 15:00
      Round table 30m