Re: [PATCH 1/2] sched/isolation: Exclude dynamically isolated CPUs from housekeeping masks

[Frederic Weisbecker]

Le Wed, Feb 28, 2024 at 09:14:13PM -0500, Waiman Long a écrit :
> The housekeeping CPU masks, set up by the "isolcpus" and "nohz_full"
> boot command line options, are used at boot time to exclude selected CPUs
> from running some kernel background processes to minimize disturbance
> to latency sensitive userspace applications. Some of housekeeping CPU
> masks are also checked at run time to avoid using those isolated CPUs.
> 
> The cpuset subsystem is now able to dynamically create a set of isolated
> CPUs to be used in isolated cpuset partitions. The long term goal is
> to make the degree of isolation as close as possible to what can be
> done statically using those boot command line options.
> 
> This patch is a step in that direction by making the housekeeping CPU
> mask APIs exclude the dynamically isolated CPUs when they are called
> at run time. The housekeeping CPU masks will fall back to the bootup
> default when all the dynamically isolated CPUs are released.
> 
> A new housekeeping_exlude_isolcpus() function is added which is to be
> called by the cpuset subsystem to provide a list of isolated CPUs to
> be excluded.

Can we instead overwrite housekeeping_boot.cpumasks from cpusets entirely and
forget about the original boot value forever?

Thanks.