Re: [PATCH v9 09/13] isolation: Introduce io_queue isolcpus type
From: Waiman Long
Date: Wed Apr 01 2026 - 15:11:13 EST
On 4/1/26 8:49 AM, Sebastian Andrzej Siewior wrote:
On 2026-03-30 18:10:43 [-0400], Aaron Tomlin wrote:
From: Daniel Wagner <wagi@xxxxxxxxxx>I set down and documented the behaviour of managed_irq at
Multiqueue drivers spread I/O queues across all CPUs for optimal
performance. However, these drivers are not aware of CPU isolation
requirements and will distribute queues without considering the isolcpus
configuration.
Introduce a new isolcpus mask that allows users to define which CPUs
should have I/O queues assigned. This is similar to managed_irq, but
intended for drivers that do not use the managed IRQ infrastructure
https://lore.kernel.org/all/20260401110232.ET5RxZfl@xxxxxxxxxxxxx/
Could we please clarify whether we want to keep it and this
additionally or if managed_irq could be used instead. This adds another
bit. If networking folks jump in on managed_irqs, would they need to
duplicate this with their net sub flag?
Yes, I will very much prefer to reuse an existing HK cpumask like managed_irqs for this purpose, if possible, rather than adding another cpumask that we need to manage. Note that we are in the process of making these housekeeping cpumasks modifiable at run time in the near future.
Cheers,
Longman