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Quantitative Finance · Glossary

What is CPU steal time, noisy neighbour?

Also known as: CPU steal time · noisy neighbour

Definition 16.7 Networks, Hardware and Trading Infrastructure · Chapter 16 — Trading in a Public Cloud

CPU steal time is the time a virtual CPU was ready to run but the hypervisor ran something else on the physical CPU; Linux reports it as “involuntary wait”. A noisy neighbour is another tenant of the same physical server or network whose load takes resources (CPU, cache, memory bandwidth, network queues) from a customer’s machine and so adds delay to it.

Casep50p90p99p99.9p99.99
Same zone (published)270–395–760
Same zone (model)270333396463743
Cross zone (published)555–755–1 905
Cross zone (model)5556577558511 908
Shared host, noisy neighbour (model)2703334007 47413 940
Table 16.1. Round-trip percentiles in microseconds: the published measurement (Hilyard et al., AWS, same subnet and cross AZ) and the simulation that firm.cloudplan fits to it; the noisy-neighbour case is an assumption. Data: nw_cloud.percentiles().
Simulation fitted to a published measurement: round-trip percentiles within a zone and across zones, and on a shared host with an assumed noisy neighbour. Crossing a zone doubles the body of the distribution; a noisy neighbour leaves the body alone and multiplies the tail. Data: fig_cloud.py.
Figure 16.3. Simulation fitted to a published measurement: round-trip percentiles within a zone and across zones, and on a shared host with an assumed noisy neighbour. Crossing a zone doubles the body of the distribution; a noisy neighbour leaves the body alone and multiplies the tail. Data: fig_cloud.py.
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