3.3. Grouped rows🔗

Rows use this key:

name, phase, activity, backend, dtype, device, module

For each key, the summary stores:

• call count;

• total and self-time sums;

• minimum, mean, median, nearest-rank p95, and maximum total duration;

• total and self heartbeats;

• supplied allocation totals and peak live bytes.

Total time can double-count nested work. Rank by self time when asking where recorded host time went. Use total time when asking how long callers waited for a named region.

The saved summary contains this real row:

{
  "key": {
    "name": "model.forward",
    "phase": "forward",
    "activity": null,
    "backend": null,
    "dtype": null,
    "device": null,
    "module": "encoder.block"
  },
  "calls": 3,
  "self_ns": 12178684,
  "total_ns": 12178684,
  "mean_ns": 4059561,
  "p95_ns": 4060907,
  "share_permille": 660
}

The three calls lasted about four milliseconds each because this example sleeps for four milliseconds. Scheduler and timer behavior account for the extra time.

The complete summary includes all required version-1 fields.