in the contributed seff module this line of perl code exists

    if (exists $step->{'stats'} && exists $step->{'stats'}{'tres_usage_in_tot'}) {

i'm trying to build a tool for job efficiency which kinda of does the what seff does, but using the --json output from sacct.  however, i cannot figure out how the tres_usage_in data is produced.

when i look at the sacct json for a job step, i see something like (sorry can't cut/paste)

{
  job_id: 1
  steps: [
    {
      tres: {
        requested: {
          max: []
          min: []
          average: []
          total: []
       },
       consumed: {
         max: []
         min: []
         average: []
         total: []
       },
       allocated: [
       ]       
     }
   }
]
    
under each of the max/min/avg/tot there are subs for cpu/disk/mem/energy/pages
but it seems inconsistent. i naively would think i could look in the consumed section of a step and compare that to the allocated/requested part and see how efficient a job was based on the resources asked for

however, in my steps the consumed part only lists energy/disk, no cpu/mem/nodes/pages/etc

so my question is, is something missing from the json output from sacct?  if not can you tell me where/how the calculations for 'tres_usage' are done