Tag: bottleneck

Abstract grid of glowing compute cells densely packed into reserved cluster capacity

Spark on Kubernetes Reserves CPU It Never Uses. Here’s the Overcommit Fix.

Spark sets executor CPU requests equal to limits, so a Kubernetes cluster reserves twice the CPU it uses and refuses to schedule pending pods. Kubernetes has no native overcommit. Here is the mutating-webhook operator I use to fix it.

By jlu, 2 weeks ago

GPUs Changed Everything. Storage Is the Bottleneck Again.

GPUs are no longer the bottleneck. Data movement is. I recently attended an online talk that stayed with me longer than most.Not because of a new GPU announcement, but because it clearly articulated something I have seen repeatedly over the years, across very different systems. That message, strongly emphasized by Read more

By jlu, 5 months2026-01-23 ago