Fault Injection > CPU Experiment

CPU Experiment

Supported platforms:

The CPU experiment generates high load for one or more CPU cores. It does this by running expensive arithmetic operations across a number of threads (one for each core targeted). When the CPU Gremlin runs, the OS Scheduler decides where the process will run and your application (and all other processes) will compete for CPU time. There's no guarantee that our process will all block others.

As of 2.58.0: When the CPU experiment is run against a container target (including Kubernetes), the target's available CPU cores reflects its cgroup limits. This value is currently rounded up to the nearest whole CPU value. For example, a CPU experiment run against a container with a CPU limit of 500m will compute a maximum of 1 cpu available. Support for fractional CPUs in these environments may come in a subsequent release.

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Options

Parameter	Flag	Required	Default	Version	Description
Cores	-c int	False	`1`	0.0.1	The number of cores to try to utilize. Capped to the number of available CPUs.
Percent	-p <0-100>	False	`100`	2.11.0	The percent of each CPU to utilize.
All Cores	-a	False	`False`	2.11.0	If set, target all available CPUs (cannot be used with -c parameter).
Length	-l int	False	`60`	0.0.1	The length of the experiment (seconds).

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Example

CPU experiments are additive up to the available CPU on the host. For example, if the typical host CPU usage is 50% and you execute a CPU Attack of 25% (magnitude), CPU usage will be increased to approximately 75% during the experiment.

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Privileges Required

Privilege	Description
FAULT_CPU	Allows performing CPU experiments

Targets