Messages in this thread | | | From | Thomas Gleixner <> | Subject | Re: Virtio-scsi multiqueue irq affinity | Date | Sat, 08 May 2021 14:26:35 +0200 |
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Yihang,
On Sat, May 08 2021 at 15:52, xuyihang wrote: > > We are dealing with a scenario which may need to assign a default > irqaffinity for managed IRQ. > > Assume we have a full CPU usage RT thread running binded to a specific > CPU. > > In the mean while, interrupt handler registered by a device which is > ksoftirqd may never have a chance to run. (And we don't want to use > isolate CPU)
A device cannot register and interrupt handler in ksoftirqd.
> There could be a couple way to deal with this problem: > > 1. Adjust priority of ksoftirqd or RT thread, so the interrupt handler > could preempt > > RT thread. However, I am not sure whether it could have some side > effects or not. > > 2. Adjust interrupt CPU affinity or RT thread affinity. But managed IRQ > seems design to forbid user from manipulating interrupt affinity. > > It seems managed IRQ is coupled with user side application to me. > > Would you share your thoughts about this issue please?
Can you please provide a more detailed description of your system?
- Number of CPUs
- Kernel version - Is NOHZ full enabled? - Any isolation mechanisms enabled, and if so how are they configured (e.g. on the kernel command line)?
- Number of queues in the multiqueue device
- Is the RT thread issuing I/O to the multiqueue device?
Thanks,
tglx
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