Re: [PATCH] usb: don't offload isochronous urb completions to ksoftirq

[Steven Rostedt]

On Fri, 15 Jun 2018 12:41:10 -0400 (EDT)
Mikulas Patocka <mpatocka@xxxxxxxxxx> wrote:

> BTW. when I subject the machine to a ping flood (ping -f), the 
> non-realtime kernel (with the patch to avoid offloading ehci urb 
> callbacks) performs better than the real-time kernel.
> 
> With the real-time kernel, all the networking work is done in the thread 
> "irq/12-eth0", that has (by default) priority -51, it consumes 30% CPU 
> time and causes sound skipping. I can avoid the skipping by lowering the 
> priority of "irq/12-eth0".

That's actually the correct thing to do. When dealing with RT
applications, one needs to modify the priority of the interrupts that
are required (or lower the ones that are not).

> 
> With non-realtime kernel, no such problem during ping flood exists.

But that was with a patched kernel?

-- Steve