---
id: "bug-1736"
status: "fixed"
status_updated: "2026-10-02"
status_note: ""
component: "controller"
severity: "unknown"
timestamp: "2026-08-30T10:45:00Z"
last_seen: "2026-09-19T09:00:00Z"
occurrences: 1
files: ["src/worker/src/xcecd_cgroups.c (collect_job_rusages -- already sends memory_swap/tasks_current", "no controller-side field to receive them)", "src/include/xce/types.h (xce_host_runusage_t -- would need new fields for swap/task-count; xce_job_runusage_t -- the peak/efficiency fields with no producer)", "src/controller/misc.c (update_host_runusage -- would need new parse branches)", "src/controller/job.c (update_job_rusages -- same open FIXME as bug-1735", "this is the other half of what it would need to cover)"]
tags: ["worker", "controller", "resource-usage", "rusage", "display-only", "reporting-only", "priority-low", "split-2026-08-30", "no-scheduling-impact", "static-analysis-only", "unreproduced-in-sandbox", "needs-design-not-just-fix", "peak-cpu-time-fixed", "swap-taskcount-fixed", "efficiency-fields-remain-scope-decision"]
related: ["bug-1735"]
fix_commits: ["5c2c6664", "6df644e6"]
legacy: true
---

# bug-1736: job CPU peak and efficiency usage fields are never computed

## Description
PRIORITY: LOW -- display/reporting only, not consumed by any scheduling logic. Split 2026-08-30 from bug-1735 at user request: the 'statistics-only' half of that finding -- resource usage fields with no scheduling relevance, purely for operator-facing job accounting/reporting (bjobs -l/bhist-style views), as opposed to bug-1735's memory+CPU-time core, which is a prerequisite for future scheduling decisions. Worker (collect_job_rusages(), xcecd_cgroups.c) already measures and sends 'memory_swap' and 'tasks_current' per job, but the controller has NO field to receive them at all (xce_host_runusage_t only has cpu_time/mem_usage -- no swap or task-count field exists) -- these two are silently dropped entirely, not just misnamed. Separately, xce_job_runusage_t's peak/efficiency fields (peak_cpu_time, peak_cpu_duration, mem_efficiency, avg_cpu_efficiency, peak_cpu_efficiency) have no computation logic anywhere in the codebase (grepped) -- nothing populates them, ever, regardless of bug-1735's fix.

## Environment
_Not recorded (migrated from buglog.json)._

## Reproduction
_Not recorded (migrated from buglog.json)._

## Root cause
See bug-1735's root_cause for the full original investigation (resname-mismatch mechanism, environment-limitation note re: this session's sandbox having no real cgroup-backed worker to live-verify against) -- this entry covers only the subset of that finding split out as lower-priority. Unlike bug-1735's memory/cpu_time (which have existing-but-mismatched fields), memory_swap/tasks_current have NO receiving field in xce_host_runusage_t at all -- the worker's measurement is a complete dead end on the controller side, not a naming mismatch. The peak/efficiency fields (xce_job_runusage_t's own top-level fields) are simply never computed by anything, anywhere -- confirmed via grep, no partial implementation exists to build on.

## Fix
(1) memory_swap/tasks_current and (2) peak_cpu_time-as-running-max -- 2026-08-30, 5c2c6664 (see git history).

(3) 6df644e6, 2026-10-01: the remaining fields, with LSF bjobs -l definitions (chosen by the user). `update_job_cpu_stats()` (`src/controller/misc.c`), called by `update_job_rusages()` (`job.c`) after each report:
- each host's `cpu_rate` = CPU-seconds gained / wall seconds since that host's previous report (`sample_time`); the job's cores = sum over its hosts. A report no later than the previous one, or with a CPU counter that went backwards, leaves the rate alone.
- `peak_cpu` = highest job cores seen; `peak_cpu_time` = it rounded (the wire field is Int32); `peak_cpu_duration` = the interval that set it. This replaces the earlier `peak_cpu_time` = running max of cumulative CPU seconds, which only duplicated `cpu_time`.
- `avg_cpu_efficiency` = cpu_time / elapsed since start / allocated slots; `peak_cpu_efficiency` = peak_cpu / slots; `mem_efficiency` = highest used_mem / the job-wide `rusage[mem]` request (`calc_wanted_job_total_resval`, per task by default, as the scheduler reserves it); all in percent, as the apiserver/xcecli models document; 0 when there is no slot count or no memory request (or the request is not a single primary one).
New persisted fields `HostRunusage.sampleTime`/`cpuRate` and `JobRunusage.peakCpu` are appended to `controller.capnp` (old WAL entries still decode) and copied by `merge_job_runusage()`. The values are controller-side only: the apiserver does not map run usage into its job model and xcecli/harness do not display these fields.

## Verification
- Test: `test_cpu_stats_*` (rate/peak/duration/efficiency, multi-host sum, mem efficiency as a peak, guards) and `test_aggregate_job_runusage_leaves_peak_cpu_alone` in `src/controller/testsuite/test_host_runusage.c` (11/11; written before `update_job_cpu_stats()` existed); WAL round trip of the new fields added to `test_wal_job_rusage_fact.c`, and the existing-host merge test `test_wru_apply_committed_entry_merges_without_freeing_live_host`: RED with the new `merge_job_runusage()` lines removed (`Expected 3.25 Was 0`), GREEN with them
- Suites: controller_unit_test 1275/1275; `xce-build.sh all asan build.jai` 126/127 -- the one failure was the known intermittent harness pty timeout bug-1902 (recurrence recorded; 3/3 reruns pass)
- Live: n/a (no consumer displays these fields; the computation is unit-tested against the same report sequence update_job_rusages() applies)

## References
- Related: bug-1735