Re: [Ksummit-discuss] [TECH TOPIC] IRQ affinity

[Theodore Ts'o <tytso@mit.edu>]

Hi Christoph,

Do you think this is still an issue that would be worth discsussing at
the kernel summit as a technical topic?  If so, would you be willing
to be responsible for kicking off the discussion for this topic?

Thanks,

					- Ted



On Wed, Jul 15, 2015 at 05:07:08AM -0700, Christoph Hellwig wrote:
> Many years ago we decided to move setting of IRQ to core affnities to
> userspace with the irqbalance daemon.
> 
> These days we have systems with lots of MSI-X vector, and we have
> hardware and subsystem support for per-CPU I/O queues in the block
> layer, the RDMA subsystem and probably the network stack (I'm not too
> familar with the recent developments there).  It would really help the
> out of the box performance and experience if we could allow such
> subsystems to bind interrupt vectors to the node that the queue is
> configured on.
> 
> I'd like to discuss if the rationale for moving the IRQ affinity setting
> fully to userspace are still correct in todays world any any pitfalls
> we'll have to learn from in irqbalanced and the old in-kernel affinity
> code.
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