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SubjectRe: [tip:sched/core] sched/isolation: Document the isolcpus= flags
On Fri, Oct 27, 2017 at 05:06:25AM -0700, tip-bot for Frederic Weisbecker wrote:
> + isolcpus= [KNL,SMP] Isolate a given set of CPUs from disturbance.
> + Format: [flag-list,]<cpu-list>
> +
> + Specify one or more CPUs to isolate from disturbances
> + specified in the flag list (default: domain):
> +
> + nohz
> + Disable the tick when a single task runs.
> + domain
> + Isolate from the general SMP balancing and scheduling
> + algorithms. This option is the preferred way to isolate
> + CPUs from tasks.

I _strongly_ object to this statement, isolcpus is _not_ the preferred
way, cpusets are.

And yes, while cpusets suffers some problems, we _should_ really fix
those and not promote this piece of shit isolcpus crap.

> The alternative -- manually setting the
> + CPU mask of all tasks in the system, can cause problems
> + and suboptimal load balancer performance. You can move a
> + process onto or off an "isolated" CPU via the CPU
> + affinity syscalls or cpuset. <cpu number> begins at 0
> + and the maximum value is "number of CPUs in system - 1".
> +
> + The format of <cpu-list> is described above.
> +

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