Fix: group bind phases correctly, and give the dsv4 driver the observability calls it omitted - #2081
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📝 WalkthroughWalkthroughThe PR changes ChangesBind grouping
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Estimated code review effort: 3 (Moderate) | ~20 minutes Merge Risk: 🟡 Moderate · up to The parser correction can still misattribute timing data when a bind omits an initial segment, causing incorrect per-bind measurements and derived statistics. Merge should wait for an unambiguous boundary rule and a regression test for this input shape. Poem
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In `@simpler_setup/tools/hbg_bind_phases.py`:
- Line 76: Update the phase-boundary logic around the “if phase in current”
check so omitted initial segments, especially absent args in the first bind,
cannot absorb the next bind’s args; ensure the following complete bind remains
separate. Add a regression test covering a first bind without args followed by a
complete bind.
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docs/dfx/hbg-bind-phases.mdexamples/a2a3/tensormap_and_ringbuffer/deepseek_v4_flash_decode/main.pysimpler_setup/tools/hbg_bind_phases.pytests/ut/py/test_hbg_bind_phases_grouping.py
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All six addressed. Each was verified against the code before changing anything; one of the suggested remedies does not hold and I took a different route, detailed below. Must-fix① Two places still taught the rule this PR calls the root cause. Confirmed at ② Should-fix③ The sentence I added was emission order labelled as the bind's own order. Confirmed, including the self-contradiction. Verified independently by sorting one bind's which is ④ The two-rank test was vacuous. Confirmed — it passes under the old parser, so it evidenced nothing. Replaced with a real split burst: rank 1 emits four segments, rank 2 lands whole inside it, rank 1 finishes. It asserts the shape is not silently made whole ( ⑤ The burst-contiguity assumption was unenforced, and violating it was silent. Confirmed, and worse than the existing guard suggests: the partial-phase check covers the three control-plane segments only, and the split bind keeps all three, so nothing fired. The tid remedy does not work here, which is why I went another way. Over all 400 bind lines of the two-rank dsv4 run, the prefix carries a single tid: The two ranks are separate processes whose bind thread has the same address, and the prefix has no pid — so grouping by tid would merge the ranks rather than separate them. Instead: the docstring now states the assumption and that nothing enforces it, and That is the same argument this PR makes about ⑥ Verification
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`BIND_CLOSING_PHASE = "arena_h2d"` carried the comment "The last segment of
a bind, and so what closes one". It is not the last. A bind prints its
segments in one burst ending `graph_upload, arena_h2d, host_view_close`,
and `host_view_close` starts after `arena_h2d` on every one of the 46 binds
in the qwen and 2-rank dsv4 logs this was measured on.
Closing on `arena_h2d` therefore attached each bind's `host_view_close` to
the next group. Every log parsed as `sizes={9:1, 10:N, 1:1}`: the first
bind lost that segment, the trailing one-segment group was dropped by the
`"host_orch" in b` filter, and the reported `host_view_close` statistics
were binds 0..N-2 labelled as warm binds 1..N-1 — including the cold bind
and excluding the last warm one. On a qwen log the median reads 0.019 ms
where it had read 0.020 ms. No other segment was affected, and
`host_view_close` is outside the control plane, so no total moved.
Group on a repeated segment name instead. A bind prints each segment it has
once, so a repeat opens the next bind — which needs no knowledge of segment
order, and so cannot be wrong in this way again.
Two assumptions remain, and neither is enforced. A burst must reach the log
uninterrupted: ranks share one stream through no lock, the line prefix
carries no pid, and its thread id is one value across both ranks over all
400 bind lines of a two-rank run, so there is no field to group by instead.
And no bind may omit a segment its successor emits before any they share,
which would put that segment in the earlier bind; `args` is emitted
unconditionally and first, so nothing can precede a shared segment today.
Both fail the same visible way — a bind whose segment set differs from its
neighbours' — and `warn_on_ragged_binds` names it. The existing
partial-phase check cannot: it covers the three control-plane segments
only, and both cases leave those intact. Keeping the boundary free of
segment-order knowledge is what preserves that visibility, since an order
constant gone stale would split every bind at the same point, leaving the
sets uniform and the mis-grouping undetectable.
The same wrong rule was written in three places, which is presumably why
none was caught. `docs/dfx/hbg-bind-phases.md` stated the segment order
backwards and told a reader grouping by hand to close on `arena_h2d`;
`simpler_setup/tools/README.md` documented it as one of the tool's three
encoded grouping rules. Both now describe the repeat rule, and the doc
separates the execution order — which is what puts `static_arena`,
`shared_mem` and `gm_heap` between `graph_upload` and `arena_h2d`, and so
why the control plane is a sum and not an interval — from the emission
order a log is read in.
The tests encode the emission order, a split burst, and a bind that omits
`args`. They fail against the old grouping with `bind 0 is not whole`, and
against a tool without the ragged check. Re-parsing the three logs this was
measured on yields 6, 12 and 40 binds of exactly 10 segments each, with no
ragged warning.
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`simpler_setup/scene_test.py` is both the SceneTest framework and the library standalone drivers reuse. A standalone driver owns its own `Worker` and never enters SceneTest's run path, so it has to make these calls itself, and nothing states which it owes. Qwen imports six helpers from that module; DeepSeek-V4 imported four. `log_torch_backend_autoload_once()` writes the record `docs/dfx/hbg-bind-phases.md` requires both arms of a comparison to carry. It exists because `torch_npu` grabs a device when imported, and a baseline that loaded it once had that cost attributed to the branch under test. The recipe sets `TORCH_DEVICE_BACKEND_AUTOLOAD=0`, but an environment variable is a request; `torch_npu_loaded` is the observed fact, and without the record a DeepSeek-V4 comparison could not rule that failure out at all. `finalize_diagnostic_outputs()` runs the postprocessors behind `--enable-dep-gen` and `--enable-scope-stats`, both of which this driver declares and forwards into `CallConfig`. Without the call the runtime wrote the raw capture and nothing turned it into the dependency graph or the scope-stats report, with no error — the flags looked like they worked. It goes in `finally`, after `worker.close()`, where the Qwen driver and SceneTest both put it: a run that raises is the one whose dependency graph is worth having, and the capture is already on disk by then, written on each `run()`'s reap path rather than at `close()`. Both omissions were silent, which is why they outlived the missing `--log-level` on the same driver: that one aborted argparse on sight. Verified on hardware. The run now logs `torch_backend_autoload setting=0 raw="0" raw_truncated=false effective=disabled torch_imported=true torch_npu_loaded=false`, and reaches the scope-stats postprocessor, which reports its input absent because the verifying run set SIMPLER_SKIP_DEVICE_RUN and that capture is device-side. That warning is itself the evidence the call is now made; before this change nothing ran.
`Host tasks` and `Graph replays` sit in the case-description table, so they read as fixed properties of the two networks rather than as measurements. Both had gone stale for DeepSeek-V4: the table said 1131 host tasks and 20 replays of a 743-task Definition, while a bind on 4d31f48 reports `tasks=129` and `graph_upload defs=8 submissions=86`. The orchestration moved most task submission onto the recording threads, which is exactly the kind of change that moves these numbers. Name the markers each row is read from, correct the DeepSeek-V4 column, and say plainly that the counts are properties of the cases, that the cases get edited, and that a current log carries both. The reference-numbers table further down already carries that warning for its durations; the counts needed it too, and more so, since nothing about their placement suggested they were ever measured.
1 participant
Follow-up to #2079. Four defects found while measuring the bind phases, all
verified against the merged
main.1 + 2. The parser closed a bind on the wrong segment, and the doc said the same thing backwards
BIND_CLOSING_PHASE = "arena_h2d"carried the comment "The last segment of abind, and so what closes one". It is not the last. A bind emits its segments in
one contiguous burst ending
graph_upload, arena_h2d, host_view_close, andhost_view_closestarts afterarena_h2don 46 of 46 binds across the qwenand two-rank DeepSeek-V4 logs this was measured on.
So every bind's
host_view_closewas attached to the next group. Every logparsed as
sizes={9:1, 10:N, 1:1}— the first bind lost that segment, thetrailing one-segment group was silently discarded by the
"host_orch" in bfilter, and the reported statistics for that phase were binds
0..N-2wearingthe labels of warm binds
1..N-1: including the cold bind, excluding the lastwarm one. On a qwen log the median reads 0.019 ms where it had read 0.020 ms.
docs/dfx/hbg-bind-phases.mdstated the same order backwards — "arena_h2druns after
host_view_close" — which is presumably why neither was caught.The conclusion it drew, that the control plane is a sum and not an interval,
holds for a different reason:
static_arena,shared_memandgm_heaprunbetween
graph_uploadandarena_h2d.The fix is not a corrected constant. Swapping in
host_view_closewouldstill encode "which segment comes last", which is the knowledge that was wrong.
Group on a repeated segment name instead: a bind emits each segment it has
once, so a repeat is the first line of the next bind. That cannot be wrong in
this way again, and it additionally survives a bind that omits a segment and
keeps two ranks sharing one log apart, since each burst is contiguous.
No other segment was affected and
host_view_closeis outside the controlplane, so no total moved — re-parsing the three logs gives the same
0.361 / 0.467 / 0.506 ms and 0.609 / 0.760 / 1.041 ms as before.
3. Two SceneTest calls the DeepSeek-V4 driver never made
simpler_setup/scene_test.pyis both the SceneTest framework and the librarystandalone drivers reuse. A standalone driver owns its own
Worker, neverenters SceneTest's run path, and so must make these calls itself — and nothing
states which it owes. Qwen imports six helpers from that module; DeepSeek-V4
imported four.
log_torch_backend_autoload_once()writes the recorddocs/dfx/hbg-bind-phases.mdrequires both arms of a comparison to carry.It exists because
torch_npugrabs a device when imported, and a baselinethat loaded it once had that cost attributed to the branch under test. The
recipe sets
TORCH_DEVICE_BACKEND_AUTOLOAD=0, but an environment variable isa request;
torch_npu_loadedis the observed fact. Without it aDeepSeek-V4 A/B could not rule that failure mode out at all — and
hbg_bind_phasessaid so on every run.finalize_diagnostic_outputs()runs the postprocessors behind--enable-dep-genand--enable-scope-stats, both of which this driverdeclares and forwards into
CallConfig. Without the call the runtime wrotethe raw capture and nothing turned it into the dependency graph or the
scope-stats report — no error, so the flags looked like they worked.
Both omissions are silent, which is why they outlived the missing
--log-levelon the same driver that #2079 fixed: that one aborted argparse on sight.
4. Two case-table counts had gone stale
Host tasksandGraph replayssit in the case-description table, so theyread as fixed properties of the networks rather than as measurements. For
DeepSeek-V4 the table said 1131 host tasks and 20 replays of a 743-task
Definition; a bind on
4d31f482reportstasks=129andgraph_upload defs=8 submissions=86. The orchestration moved most tasksubmission onto the recording threads, which is exactly the kind of change that
moves these numbers.
Each row now names the marker it is read from, the DeepSeek-V4 column is
corrected, and the text says the counts are properties of the cases, that the
cases get edited, and that a current log carries both.
Verification
parser with
bind 0 is not whole. Re-parsing the three logs this wasmeasured on now yields 6, 12 and 40 binds of exactly 10 segments each, where
before every log had one 9-segment bind and one discarded 1-segment group.
torch_backend_autoload setting=0 raw="0" raw_truncated=false effective=disabled torch_imported=true torch_npu_loaded=false.SIMPLER_SKIP_DEVICE_RUN=1and the capture is device-side. What the run doesshow is
scope_stats.jsonl not produced; skipping scope_stats plot— awarning only reachable from inside
finalize_diagnostic_outputs, and soitself the evidence that the call is now made. Before this change nothing ran
and there was no warning either. A run that does not skip the device would
exercise the plot end to end.
tests/ut/py/, filtered to the affected tools and drivers: 141 passed.pre-commitpasses on all four files.Still open
Not in this PR, and left in place deliberately: the measurement-reading rules in
docs/dfx/hbg-bind-phases.mdneed two corrections that a 20-round sessionestablished, and both change how a comparison is judged rather than fixing a
defect.
min-of-sums does not converge in round count, and cannot: it is anextreme-order statistic. Measured on one DeepSeek-V4 session it stepped
0.763 ms (2 rounds) → 0.555 (6) → 0.520 (14) and was still moving at 20. The
doc names it the single deciding statistic without saying that two arms must
therefore use an identical round count. The median converges by round 5
(0.79–0.84 ms) and is round-count insensitive.
of that session the rank that binds first has
graph_uploadmedian 0.193 msagainst 0.139 ms, and
host_orch0.470 ms against 0.590 ms — pooling themmixes two distributions. The doc asks only that one cold bind per rank be
dropped.