Skip to content

CONCEPT Cited by 2 sources

Performance isolation

Definition

Performance isolation is the property that one tenant's workload does not observably affect another tenant's latency or throughput — distinct from simple fairness (everyone gets some share) and from load balancing (the total work is spread across resources). It is the strong form of the answer to concepts/noisy-neighbor: not "the worst case is rarer," but "your tail is not a function of my behavior."

Why it matters

From the EBS post:

As AWS evolved, we learned that we had to focus ruthlessly on a high-quality customer experience, and that inevitably meant that we needed to achieve strong performance isolation to avoid noisy neighbors causing interference with other customer workloads.

Performance isolation is what converts a multi-tenant storage service from "mostly fine on average" into something safe to host a customer's mission-critical application on. It's the property Provisioned IOPS was created to sell in 2012.

How EBS achieves it (as of 2024)

Across layers, each of these contributes a piece:

  • SSDs — collapse per-operation variance at the media level.
  • systems/nitro offload — remove hypervisor queue depth coupling between tenants; stop stealing customer CPU for IO/encryption.
  • Hardware-accelerated EBS encryption — at line rate; key material isolated from the hypervisor. No shared-CPU tax between tenants for crypto.
  • systems/srd — multi-path, out-of-order, offload-friendly transport removes TCP's head-of-line variance.
  • Instrumentation + canaries (patterns/full-stack-instrumentation) — so any regression of isolation is caught as it lands.
  • Custom systems/aws-nitro-ssd — co-designed so media variance is known, not inherited from an off-the-shelf SSD controller's firmware choices.

Seen in

Last updated · 200 distilled / 1,178 read