feat: add cpu isolation for system, perf and benchmark

[not-matthias]

No description provided.

[GuillaumeLagrange]

Two subsequent questions:

1. Did you try the effect of existing walltime benchmarks ? We may need to prepare users for breaking changes on this regard.

2. How does this behave when the user is not root on the machine ? (Edge case obviously since macro runners are not concerned)

[not-matthias]

Did you try the effect of existing walltime benchmarks ? We may need to prepare users for breaking changes on this regard.

Not yet. Will do that tomorrow on an AWS EC2 instance.

How does this behave when the user is not root on the machine ? (Edge case obviously since macro runners are not concerned)

We already need root to install perf/valgrind if it's not installed. I made sure that the command can be run without root, which is the reason why we can't use systemd-run with a custom slice that pins the bench process to a specific core. We would have to run it with systemd-run --user which puts it into the user.slice.

[GuillaumeLagrange]

lgtm