2022.03.28 - ovis-hpc/ovis-wiki GitHub Wiki

  • Discussion
    • Need to update documentation and make sure that when someone googles for LDMS and related they get something appropriate returned
    • "News" should not refer to something that happened a year ago!!!
  • Presentation
    • LDMS_V_LIST and LDMS_V_RECORD
      • Description
      • Use cases
      • API Overview
    • Comparison of samplers converted to use lists and records
      • procnetdev
      • procstat
  • Discussion of pros and cons of converting old samplers to use lists and records vs. writing new versions of samplers
  • Metric List and Records:
    • Schema with varying sizes and metric sets that can have varying numbers of entities in order to accommodate varying systems and user-specific metrics.
    • List: linked-list, LDMS list can be of different value types.
      • In the future we would like to impose "same-type" restrictions because the storage plugins in LDMSD do not support mixed-type lists.
      • While the system can handle it, it is highly not recommended for the consumer
      • Any entry can also be a list (list of lists)
      • Lists are dynamically allocated from the metric's "heap"
      • Heap follows static data: the meta data and the data itself. The meta data carries info on the type of data. Data follows the meta data and contains the metric values and the heap.
    • Records:
      • Analogous to 'struct' in C
      • List of Record API in the header files
      • The ability to allocate records and manipulate the member data.
      • Able to add record instances, access record in the list and access record members.
      • Note: A record cannot contain a list.
    • Discussion Notes:
      • LDMS creates the heap while LDMSD creates the schema.
      • Records should be either all JSON or not. Currently a mix.
  • Next meeting:
    • How does the store handle and interact with the Lists and Records.
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