[PATCH v12 00/13] blk: honor isolcpus configuration

[Daniel Wagner]

On Mon, Apr 27, 2026 at 12:55:20PM +0200, Florian Bezdeka wrote:
> This topic reminds me of a discussion started by Tobias [1] some time
> ago about IRQ spreading of network drivers. The problem was (and still
> is) that network drivers ignore any CPU isolation when spreading out
> device IRQs.
> 
> In general we have two different CPU isolation mechanisms:
>   - The static one, via isolcpus= cmdline parameter
>   - The dynamic one, via cgroups(v2) cpuset controller
> 
> This series is only taking the static "world" into account, right? Are
> there any plans to honor the CPU isolations configured the dynamic
> way?

Dynamic configuration would require every driver to fully support
reconfiguration during runtime. Only a handful of drivers, such as
nvme-pci, are currently able to handle this.

The first task, teaching a wide range of drivers to honor CPU isolation
at boot time, is already going to be a significant amount of work.

> It has been a while since the last investigations on my end. Last time I
> went through the code, the IRQ core was completely decoupled from the
> dynamic configuration via cgroups. Are there any plans to fix that gap?

Which use case are you actually aiming to support? While dynamic
reconfiguration would be ideal, the amount of work to get there is
significant. I won't be signing up for it.