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fix(resource_plan): take last two lscpu fields, not [1]/[2] (#332 review)

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JustVugg caught a regression by running the PR: the code asked
`lscpu -p=CPU,Core,Socket` and read fields[1]/fields[2], but the comment's
claim was inverted -- `lscpu -p=<list>` emits EXACTLY the requested columns
(no CPU prefix), while bare `lscpu -p` prepends CPU.

On machines where the requested list is short or lscpu collapses to two
columns, every line was skipped by the `< 3` guard, cores stayed empty, and
the code fell through to os.cpu_count() -- the LOGICAL count. Result: 6
physical cores reported as 12 (SMT over-subscription), the opposite of the
fix.

Correct per review:
  - ask lscpu for exactly 'core,socket'
  - take fields[-2], fields[-1] (correct whether or not CPU is prepended)
  - keep the warning scaffolding + the _resolve_physical_cores clamp
    (those are the actual #325 fix; only the indexing was wrong)

Test now exercises BOTH the 2-column (-p=core,socket) and 3-column
(bare -p, CPU prefix) layouts, asserting 12 physical cores each. The
2-column case is the one that regressed: old parser returns 24, new
returns 12.
This commit is contained in:
woolcoxm
2026-07-17 15:23:51 -04:00
parent bd3efb1c97
commit 171aa69fcb
2 changed files with 41 additions and 19 deletions
Download Patch File Download Diff File Expand all files Collapse all files
c/tests/test_resource_plan.py
+25 -10
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@@ -98,16 +98,31 @@ class ResourcePlanTest(unittest.TestCase):
return subprocess.CompletedProcess(args=[], returncode=0,
stdout=stdout, stderr="")
# 1 socket, 12 cores, 2 SMT siblings -> 24 threads, 12 physical cores.
# lscpu prepends the CPU column, so output is CPU,Core,Socket.
rows = [f"{cpu},{core},0" for core in range(12) for cpu in range(2)]
blob = "# CPU,Core,Socket\n" + "\n".join(rows)
with mock.patch("resource_plan.subprocess.run", return_value=lscpu(blob)), \
mock.patch.object(sys, "platform", "linux"):
plan = build_plan(self.model, available_memory=16 * GB,
available_disk=1, gpus=[])
env = environment_for_plan(plan)
self.assertEqual(plan["cpu"]["physical_cores"], 12)
self.assertEqual(env["OMP_NUM_THREADS"], "12")
# The parser must return 12 physical cores under BOTH lscpu layouts:
# - 2-col: `lscpu -p=core,socket` emits exactly [core,socket] (this is
# what the probe actually requests; the previous fields[1]/[2]
# indexing skipped every line here and fell through to the
# logical count -> the regression JustVugg caught).
# - 3-col: bare `lscpu -p` prepends a CPU column -> [cpu,core,socket].
# Taking the last two fields is correct in both cases.
layouts = {
"2-col (-p=core,socket)": (
"# core,socket\n" +
"\n".join(f"{core},0" for core in range(12) for _ in range(2))),
"3-col (bare -p, CPU prefix)": (
"# CPU,Core,Socket\n" +
"\n".join(f"{cpu},{core},0" for core in range(12) for cpu in range(2))),
}
for label, blob in layouts.items():
with mock.patch("resource_plan.subprocess.run",
return_value=lscpu(blob)), \
mock.patch.object(sys, "platform", "linux"):
plan = build_plan(self.model, available_memory=16 * GB,
available_disk=1, gpus=[])
env = environment_for_plan(plan)
self.assertEqual(plan["cpu"]["physical_cores"], 12, label)
self.assertEqual(env["OMP_NUM_THREADS"], "12", label)
def test_plan_does_not_set_omp_affinity_vars(self):
# The real #325 regression: --auto-tier set OMP_PROC_BIND=spread +