[Halld-offline] Offline Software Meeting Minutes, July 23, 2014

[Mark Ito]

Folks,

Please find the minutes below and at 
https://halldweb1.jlab.org/wiki/index.php/GlueX_Offline_Meeting,_July_23,_2014#Minutes 
.

   -- Mark
__________________________________________

GlueX Offline Meeting, July 23, 2014
Minutes

    Present:
      * CMU: Paul Mattione, Curtis Meyer
      * FSU: Aristeidis Tsaris
      * IU: Matt Shepherd
      * JLab: Mark Ito (chair), David Lawrence, Nathan Sparks, Mike Staib,
        Simon Taylor, Beni Zihlmann
      * NU: Sean Dobbs
      * UConn: Richard Jones

Review of minutes from July 9

    We reviewed the [19]minutes.
      * Automatic Tests -- Both the single-track and b1pi tests are now
        succeeding. Simon checked in a fix to tracking and David a fix to
        tracking event display.
      * EVIO Build -- Mark has a makefile in scripts/build_scripts that
        will build the most recent version of EVIO. EVIO has not yet been
        incorporated into the global build system (i. e., gluex_install).
      * BCAL Timing -- David reported that Mark Dalton has noticed that
        there is an asymmetry in how the timing is done in simulation and
        real data for the BCAL. In the simulation the pulse shape is
        simulated, and a threshold applied to determine the time. In data,
        a digital constant-fraction discriminator algorithm is used. In the
        reconstruction a time-walk correction is applied. In the case of
        the real-data, this correction is largely unnecessary and in fact
        hurts the time resolution. The nominal plan being discussed in the
        BCAL group is to emulate the real-data algorithm in the simulation
        and drop the time-walk correction in the reconstruction.
      * Global Event Time Smearing -- Richard has started work on this on a
        branch of the Subversion repository. Paul has looked at
        incorporating the effect in his analysis library, but thought that
        the start counter time resolution should be more realistic that it
        is now to make progress. Others thought that even a constant RMS
        time smearing for all positions in the counter would be sufficient
        to make progress on the problem of picking out the right RF bucket.
        Turns out there is a command line parameter for mcsmear to set the
        this smearing constant, "START_SIGMA".
      * Truth vs. Hits -- Richard reminded us that the parallel scheme of
        truth information and smeared hit information is already in place
        for the CDC, FDC, FCAL, and BCAL. He is making the scheme global,
        adding it to the start counter for example.

MD5 Check-Sums and Resource Files

    David described the problem that Matt ran into where the downloading of
    resource files (in his case the magnetic field map) was interrupted,
    resulting in a corrupt file that crashed programs that used it. The
    solution is to use the MD5 check-sum that is generated and downloaded
    along with each resource file to check file integrity each time the
    file is read. David is working on implementation for the next version
    of JANA.

Haswell CPU Testing

    David reported on tests he has done bench-marking a demo machine that
    SciComp had on loan for this purpose. He compared the demo Haswell
    machine with an Ivy Bridge gluon machine in the Counting House.
          Parameter        Haswell Ivy Bridge
    CPU Chips              2       1
    cores/chip             18      16
    hyper-threads per core 2       2

    He did two types of comparisons, one with a dummy, but CPU-intensive,
    JANA application and another with bggen data, looking at hdgeant,
    mcsmear, and hd_ana, one by one. See [20]his slides for the plots. He
    sees big improvements with the new Haswell architecture, as much as 71%
    per core (for mcsmear). Richard remarked that this might be more
    improvement that we have a right to expect based on a quick Google
    survey. There were several questions about the exact configuration of
    the new system (and of the old for that matter) that might affect the
    comparison, but the results are nonetheless encouraging and may save
    "us" some money.

Data Challenge 3

    David reported that the complete chain from simulated data in HDDM
    format to EVIO format to DANA classes is ready to go. The current
    system only creates EVIO data in single-event form (as opposed to
    multi-event block form) [terminology?]. Mark will start to test this
    part of the chain, i. e., creating simulated raw data and putting it on
    tape. He will also start working on a new software stack to do
    reconstruction starting from the tape files.

References

   19. 
https://halldweb1.jlab.org/wiki/index.php/GlueX_Offline_Meeting,_July_9,_2014#Minutes
   20. 
https://halldweb1.jlab.org/wiki/images/d/d8/20140723_haswell_testing.pdf

-- 
Mark M. Ito, Jefferson Lab, marki at jlab.org, (757)269-5295