schedstat: per-cycle GC mark assist breakdown#8
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Replace the cross-cycle mark assist summary (and the verbose-only
per-cycle table) with a single per-cycle GC detail section shown
unconditionally after the sweep summary. For each GC cycle we now show:
Cycle N @ t=Xms, duration: Y
Mark assist: N events, M goroutines, total: T
g<id> <name> N assists, total T, max T @ t=Xms
...
Cycles with no mark assists collapse to a single "(no mark assists)"
line. The previous aggregate "Mark assist: ..." line is dropped — the
per-cycle view contains the same information at higher fidelity, plus
the cycle that the burst belongs to. The verbose-only per-cycle table
is removed since the new section subsumes it.
GC analysis section order is now: cycle summary, STW, latency
comparison, sweep, per-cycle detail.
JSON: GCMarkAssist and the old GCPerCycleBreakdown types are removed;
the new GCPerCycleDetail / GCCycleDetail / CycleAssistG types take their
place. JSON goldens regenerated.
Co-Authored-By: roachdev-claude <roachdev-claude-bot@cockroachlabs.com>
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Summary
gc.mark_assist; replacesgc.per_cycleshape with newGCPerCycleDetailcarrying per-cycle assist totals + top goroutinesMakes it easy to spot which specific GC cycle was problematic at a glance.
Test plan
go test ./...— text + JSON golden tests passgo run . testdata/single-node-lowcpu-gcassist.bin --gc— 2-cycle tracego run . testdata/experiment-upsert1000-gateway.bin --gc— 1-cycle tracego run . testdata/experiment-upsert1000-leaseholder.bin --gc— 2-cycle trace