stragglers

Separate a longer step from lower throughput, trace the dependency that changed, and distinguish input, workload, device and path causes. Then calculate whether a repair recovers more time than it costs.

Trace a link flap through transport and job recovery. Calculate detection, restart and replay costs, and learn what continuous counters and timed tests can actually establish.

Build observability around durable useful progress and aligned phase timing, showing why full-step timers can hide the late rank.

Find the critical-path delay using local phase timing and controlled comparisons, rather than diagnosing a node from utilization or clock ratios.

Measure throughput at several power limits, translate the facility target into a GPU budget, and account for slower ranks before changing the fleet.