Re: [PATCH 02/13] irq: Introduce IRQD_AFFINITY_MANAGED flag

On 06/14/2016 09:58 PM, Christoph Hellwig wrote:

From: Thomas Gleixner <redacted>

Interupts marked with this flag are excluded from user space interrupt
affinity changes. Contrary to the IRQ_NO_BALANCING flag, the kernel internal
affinity mechanism is not blocked.

This flag will be used for multi-queue device interrupts.

It's great to see that the goal of this patch series is to configure 
interrupt affinity automatically for adapters that support multiple 
MSI-X vectors. However, is excluding these interrupts from irqbalanced 
really the way to go? Suppose e.g. that a system is equipped with two 
RDMA adapters, that these adapters are used by a blk-mq enabled block 
initiator driver and that each adapter supports eight MSI-X vectors. 
Should the interrupts of the two RDMA adapters be assigned to different 
CPU cores? If so, which software layer should realize this? The kernel 
or user space?

Sorry that I missed the first version of this patch series.

Thanks,

Bart.